ALBERT

Description: The objective of this study was to compare the effects of various pretreatments on the X-ray identification and quantification of clay-sized minerals from some podzolic B horizons. After soil samples were treated with H2O2 to remove organic matter, clay fractions were dispersed, separated, and freeze-dried. A portion of each clay sample was subjected to the following pretreatments: ultrasonic bath, extraction by citrate-dithionite, extraction by 0.5 N NaOH, and extraction by Tiron. Oriented slides were used for identification and quantification of clay minerals after each pretreatment. The X-ray patterns for ultrasonically dispersed samples were used as a basis for evaluating the effectiveness of the three chemical pretreatments. Tiron pretreatment was found to be the most suitable method for removal of amorphous material from clay separates of podzolic B horizons. The traditional citrate-dithionite method was not effective in removing amorphous Si from clays. The 0.5 N NaOH method is not recommended because it resulted in significant destruction of phyllosilicates and it was not effective in removing amorphous Fe.

Description: This study was conducted to evaluate the impact of tillage and fertilization practices on soil organic carbon (organic-C) and the distribution of phosphorus between inorganic (Pi) and organic (Po) pools in a clay and sandy loam soil under a continuous corn (Zea mays L.) production system. Tillage treatments were established in the fall of 1981. The soils for this study were sampled (0- to 10-cm and 10- to 20-cm) in June 1988. Treatments consisted of three types of tillage: (i) conventional (CT): fall moldboard ploughing with two spring diskings; (ii) reduced (RT): with either fall chisel ploughing (1981–1986) or no fall tillage (1987) followed by one spring disking, and (iii) no-till (NT); and two types of fertilization (i) inorganic (I): 170 kg N ha−1. 80 kg P2O5, ha−1, 75 kg K2O ha−1, and (ii) organic fertilizer (O): dairy manure applied to give 170 kg N ha−1 plus 80 kg P2O5, ha−1 from inorganic P fertilizer. Even though a lime application was made in the fall of 1985, soil pH was significantly lower in the I fertilizer treatments. Reduction of tillage intensity resulted in a lower pH in the surface layer of the sandy loam soil. Tillage did not affect soil organic-C, or total soil Po (soil-Po) in either soil. Compared with the I fertilizer treatment, the O fertilizer treatment resulted in increased levels of soil organic-C and soil-Po only in the sandy loam soil. Labile levels of Po in the soil were not affected by treatments. Increased soil-Po levels possibly resulted from an increase in stable Po complexes. Moderately labile Po levels were not affected by treatments in the clay soil. In the sandy loam soil, O fertilization decreased moderately labile Po levels in the surface layer of the NT treatment, and increased this P fraction in the 10- to 20-cm soil layer of the RT and CT treatments. In the surface layer of both soils, labile levels of Pi were greater for the O fertilization treatment (approximately 40 and 47% higher for the clay and sandy loam, respectively), and were lower under CT. Increased labile Pi levels were associated with the O fertilizer treatment in the 10- to 20-cm depth increment in the sandy loam soil only, suggesting a greater downward movement of P with manure applications. Key words: Conventional tillage, zero-tilled, no-till, reduced tillage, manure, P fractionation

Description: Concern has been expressed that reduced tillage systems may lead to excess soil compaction, negatively impacting on crop growth. The objectives of this study were to determine the effects of tillage systems zero (ZT), minimum (MT) and conventional tillage (CT) and crop rotations on soil bulk density and penetration resistance after 4 yr on an Indian Head heavy clay soil, in southeastern Saskatchewan. Moisture content was similar among tillage systems, except for slight differences in the lower soil depths with crop rotation. Penetration resistance and bulk density of a heavy clay soil were increased in the surface 10 cm of the soil by ZT as compared to CT management. However, in the deeper soil zones, tillage system did not consistently influence either bulk density or penetration resistance. Inclusion of peas in the crop rotation had a moderating effect on bulk density and penetration resistance, while inclusion of flax in a continuous rotation increased bulk density and penetration resistance in the surface soil profile. At the 30- to 45-cm depth, ZT had a lower bulk density than CT or MT in the rotation which included fallow, possibly because the tillage operations associated with the cultivated fallow led to compaction in the deeper soil zone. Penetration resistance was great enough in the deeper soil zone in all tillage systems to restrict rooting, but difference due to tillage treatment or cropping rotation was not sufficient to markedly influence crop production. Key words: Penetration resistance, bulk density, crop rotation, tillage

Description: A single batch application of phosphorus once in several years might be a more economical practice for wheat production in Western Canada than the traditional annual application at seeding time. Annual phosphorus applications and batch applications once every 8 yr were compared. Response functions were estimated for annual applications for two locations in Saskatchewan and two in Manitoba. The response functions were used to determine the optimum application rates at each location. These optimums were compared with the profitability of the batch application to determine the economic optimum phosphorus application strategy. Three wheat/fertilizer price ratios were used in the analysis to examine the effect of changes in relative prices. The 100-kg batch application was economically preferred to annual applications for all three price ratios at three of the four locations. Only at Swift Current, Saskatchewan was the batch application not economically justified. The 100-kg batch application was economically superior to the 200-kg application at all locations studied.

Description: The effect of labile inorganic phosphate (Pi) status of the soil on the decomposition of added cellulose and on the immobilization, mineralization, and redistribution of native and added P in soils was studied in a greenhouse incubation experiment. Cellulose was added at 765 μg C∙g−1 soil with and without P (9 μg∙g−1 soil) every 30 days under adequate N, H2O, and constant tempreature to two soils of different available P status. Lack of P eventually slowed down decomposition of added C, but this effect was partially compensated for by increased mineralization of organic P (Po) forms. Added P was redistributed to both P, (58–69%) and Po (42–31%) forms; higher amounts of Po were found in the soil with the highest Pi status. The correlation between microbial P uptake and solution P values was significant, and microbial C:P ratios ranged from 12:1 under high available P conditions to 45:1 where P was in low supply.

Description: A theory is presented for the distribution of load pressures over the different phases in an unsaturated soil. It provides differential and integral relations between the equilibrium liquid pressure, the equilibrium solid pressure and the load pressure. Mechanical and thermodynamic models are presented by which the effective stress in unsaturated soils is defined. The value of the effective stress is then calculated for a certain state of a clay soil.

Description: Twenty-five soil media representing 13 subsoils and organic overlays, and their mixtures, that had been used in pot culture fallow, or for growing root, leafy vegetable and grass crops, were studied to determine if the benefits of organic amendments to crop yields in optimally watered and fertilized soils were due to improvements in soil physical conditions. The soils were subjected to particle and aggregate size fractionation; and the stability of the aggregates was determined. The results suggested that admixing of residual organic overlays improved the structure of all mineral subsoils, except perhaps an alluvial sand. Aggregation and stability of aggregates 〉 2 mm were improved, thus leading to improved aeration, root proliferation and to increases in crop yields. In addition, grass crops were shown to be more effective than root and leafy crops for improvement of the structure of the various soils. Key words: Organic soils, soil aggregation, soil structure stability

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Description: It is becoming common for soil surveys to be made of the same area at different intensities and published at different scales. The principles of cartographic generalization are discussed that control the relationships between the map units and delineations on maps made from such surveys. A study of two sets of maps showed that almost no lines were coincident. Up to 20% of the small scale delinations could be ’inliers’ of different soils and about 15% of the large scale delineations would be outside their small scale equivalents. The same discrepancies are to be expected between large scale soil maps and the smaller scale maps of physiography or vegetation that are often used to stratify soils. Reasons for these discrepancies are discussed under the headings of simplification and classification. Recommendations arc made to guide the preparation of maps and legends for different intensities and scales of survey in the same area. These recommendations have practical implications for the planning of surveys and the designs of computer-based autocartography systems.

Description: The objectives of this study were to find ways to improve the accuracy of soil fertilizer recommendations by taking into account the variation in bulk density (BD) of organic soils. To achieve this end, field BD values of 30 organic soils (0.100–0.504 g/mL) were used to evaluate methods of measuring the BD in the laboratory by means of correlation and regression techniques. A simple and rapid procedure using the reconstituted BD of field-moist soils was the most accurate means of determining the average field BD in the laboratory, as indicated by the correlation coefficient obtained between the BD values obtained by this method and those in the field (r = 0.975**). The second most accurate method relied upon the exponential relationship between the water content of soils and their BD (R2 = 91.1 %). The least exact method of correcting for BD variations was to scoop a volume of dried (65 °C) and sieved (2-mm) soils, as is done in some soil test laboratories. Although the values obtained by this method were related (r = 0.502**) to the field data, drying caused shrinkage of soils, thereby increasing their BD about twofold. Soil pH (r = 0.716**) and percentage ash contents (r = 0.851**) were also related to the field BD of soils. These tests could be used to estimate the BD of soils when the preferred method cannot be used. Regression equations are provided for relating appropriate test values to the BD of organic soils.

Description: Atomic absorption spectrophotometric measurements of Al in plant digests and neutral salt extracts of soils were studied. Using a new lamp (Westinghouse design) and 5 × scale expansion, 1.0 ± 0.08 ppm Al was measured. Lanthanum (2000 ppm) suppressed enhancements from Na, K, Sr, Fe and a mixture of a large number of constituents. The measurements in plant digests were independent of dilution, gave complete recovery of added Al and showed excellent agreement with the 8-quinolinolate colorimetric values. Similarly, there was complete recovery from soil extracts, but the measurements by atomic absorption were larger than by 8-quinolinolate or Aluminon. It was concluded that the new lamp provides adequate sensitivity, stability and freedom from interferences so that atomic absorption can be used for routine measurements of Al in plant digests and neutral salt extracts of soils.

Description: Five vegetation treatments were established in 1.2 m × 1.2 m plots in 1990: (1) bare mineral soil, (2) Epilobium angustifolium, (3) Rubus spectobilis, (4) Alnus rubra and (5) a mixture of all three species. Soil temperatures were measured at 10-cm depths in three replicates of each treatment during the early summer of 1991. Mean, maximum and minimum temperatures always exhibited the same rank order of treatments — bare 〉 Epilobium 〉 Rubus 〉 mixture 〉 Alnus — but the latter four treatments were not readily distinguishable. A data-adjustment procedure based on Fourier analysis was conducted and its utility discussed for use in the separation of treatment effects where observations exhibit a detectable diurnal cycle. Using this method, the soil thermal regime of the Epilobium treatment was demonstrated to be statistically distinct from that of the bare plots and from those of the other vegetation treatments. Key words: Fourier analysis, diurnal pattern, soil temperature, vegetation effects, microclimate

Description: Sulfur deficiency has become a widespread limitation to crop production in western Canada. A variety of S sources are commercially available to alleviate these deficiencies but not all are equally effective. Three elemental S products (a finely-divided suspension and two elemental S + bentonite) and ammonium sulfate were compared over a 3-yr period in central Alberta. These products were applied to barley and canola at various rates (0–120 kg S ha−1) in a factorial arrangement with various supplemental rates of sulfate-S (0–40 kg ha−1) in two experiments Fertilizers affording effective and reliable alleviation of S deficiency in the year of application included sulfate forms and finely-divided elemental S products that can be readily mixed into the soil. The residual benefits of the various fertilizer products examined appeared to be comparable despite large differences in short-term availability. The absence of appreciable residual advantage of slow-release elemental S products was attributed to the short duration of S assimilation by canola and barley and the susceptibility to leaching of S oxidized after that period. Key words: Barley, canola, residual, rotation, S fertilizer, uptake, yield

Description: A common pedological feature in Podzols and Podzolic-like soils in the forest region of Hinton, Alberta is the presence of nodules in the Bf horizons with diameters of 1—20 cm. The nature of these nodules was investigated through physical, chemical, mineralogical and micromorphological examinations. Results showed that the nodule microstructure is mainly bridged-grain type compared to dominantly pellicular type for the soil matrixes. The basic building blocks are (a) coarse components (〉 5 μm): quartz, feldspars mainly albite, pseudo sands, sand-sized chlorites and small quantities of anthophyllite, sillimanite, andalusite and lithogenic hematite; (b) fine components (

Description: Copper, in the form of Cu-polyflavonoid, was applied at 50 or 100 ppm to surface samples of nine Wisconsin soils varying from 0.8 to 12.5% organic matter. The effects on yield and on plant uptake of Cu, Zn and Mn were evaluated using oats (Avena sativa L. cv. Lodi). Complexed Cu additions increased extractable Cu, had little effect on extractable Zn, but also increased extractable Mn. Complexed Cu decreased plant uptake of Zn, but increased uptake of Mn. Interactive effects of organic matter, clay, available phosphorus and Zn appeared to occur with respect to plant yield and Cu, Zn, and Mn uptake.

Description: In a soil incubation experiment with different rates of Zn, the amounts of Zn extracted with 0.005 M DTPA, 1 M MgCl2, and 0.01 M CaCl2 increased with an increase in the organic matter content of a neutral sandy loam soil and with alfalfa added as an organic amendment. Addition of muck and peat increased the amount of Zn exchanged with 1 M MgCl2 but decreased the amount soluble in 0.01 M CaCl2, whereas addition of clay increased the amount of exchangeable Zn but decreased the amounts in the DTPA and 0.01 M CaCl2 extracts. Liming of an acid sandy loam soil (pH 4.9) to about the neutral point reduced the amounts of extractable Zn markedly. A pretreatment of the soils with phosphate almost invariably increased the amounts of extractable Zn. In a corresponding pot experiment, the highest rate of Zn (250 ppm) reduced the yield of corn slightly, prevented the growth of lettuce, and reduced the yield of alfalfa markedly when these crops were grown successively in the acid soil. The concentration of Zn reached levels of 792 ppm in the corn and 702 ppm in the alfalfa. Addition of 50 ppm Zn to the acid soil restricted the growth of lettuce and increased the concentration of Zn to 523 ppm. Despite discrepancies, the concentrations of Zn in the plants as influenced by soil organic matter, organic amendments and liming were usually in accord with the amounts of Zn extracted from the soils. But the P pretreatment tended to decrease the concentration of Zn in corn and lettuce. The mean weight concentrations of Zn in the three species were correlated significantly with the amounts of Zn extracted with 0.005 M DTPA (r = +0.73), 1 M MgCl2 (r = +0.93) and 0.01 M CaCl2 (r = +0.90).

Description: The results of two studies are reported: (1) a comparison of colorimetric and atomic absorption measurements of Fe and Al in dithionite, oxalate, and pyrophosphate extracts of soils; and (2) a comparison among nine Canadian laboratories of measurements of dithionite-, oxalate-, and pyrophosphate-extractable Fe and Al in six soils. Colorimetric and atomic absorption analyses gave the same measurements of Fe and Al in dithionite, oxalate, and pyrophosphate extracts of soils. Data reported by six Canadian laboratories showed close agreement; data reported by three laboratories showed poor agreement, indicating a need for reference soil samples containing known amounts of extractable Fe and Al to standardize laboratory procedures. Atomic absorption analysis of the extracts is much more rapid than colorimetric analysis and details of the atomic absorption methods are appended.

Description: We used a simple empirical model to predict denitrification rates from measurements of bulk soil properties. Boundary analysis was used to define relationships between denitrification rate and each of air-filled porosity, respiration rate and mineralizable-C content. The ratio of measured denitrifying enzyme activity to the maximum measured value was used to account for variation in amounts of enzymes and numbers of denitrifiers in soil. Nitrate content had little effect on denitrification rate and was excluded from the model. Because the model did not account for microscale variability, it did not accurately predict rates in individual soil cores. Nevertheless, population means and distributions of predicted and measured values were similar. The seasonal patterns of mean values of predicted and measured denitrification rates were also similar over the second half of the sampling period, which extended from May to November. The model did not account for appreciable denitrification on three dates in May. This discrepancy indicated that environmental regulation of denitrification may not be uniform over the season. The model was not sufficiently sensitive to factors influencing episodic events. Key words: Denitrification rate, model, boundary line

Description: The effects of crop rotations and various cultural practices on soil organic matter quantity and quality in a Rego, Black Chernozem with a thin A horizon were determined in a long-term study at Indian Head, Saskatchewan. Variables examined included: fertilization, cropping frequency, green manuring, and inclusion of grass-legume hay crop in predominantly spring wheat (Triticum aestivum L.) production systems. Generally, fertilizer increased soil organic C and microbial biomass in continuous wheat cropping but not in fallow-wheat or fallow-wheat-wheat rotations. Soil organic C, C mineralization (respiration) and microbial biomass C and N increased (especially in the 7.5- to 15-cm depth) with increasing frequency of cropping and with the inclusion of legumes as green manure or hay crop in the rotation. The influence of treatments on soil microbial biomass C (BC) was less pronounced than on microbial biomass N. Carbon mineralization was a good index for delineating treatment effects. Analysis of the microbial biomass C/N ratio indicated that the microbial suite may have been modified by the treatments that increased soil organic matter significantly. The treatments had no effect on specific respiratory activity (CO2-C/BC). However, it appeared that the microbial activity, in terms of respiration, was greater for systems with smaller microbial biomass. Changes in amount and quality of the soil organic matter were associated with estimated amount and C and N content of plant residues returned to the soil. Key words: Specific respiratory activity, crop residues, soil quality, crop rotations

Description: Inorganic phosphorus (P) is generally believed to be relatively immobile in Chernozemic soils. However, available P (e.g., Olsen-P) has been found at depth in some soils and this has been postulated to be either the result of leaching or of transportation by plant roots. Lagumes, in particular, are believed to be involved in the latter mechanism. A long-term (34-yr) crop rotation study conducted on a heavy clay, thin Black Chernozemic soil at Indian Head, Saskatchewan, was sampled to a depth of 4.5 m in May and September 1991, to determine the influence of fertilization, cropping frequency, legume green manure and legume-grass hay crops on Olsen-P distribution in the soil profile. The results indicated that Olsen-P may indeed leach in Chernozemic soils, especially when fallow-containing cropping systems are fertilized. It also appeared that deep-rooted legumes, such as sweetclover Melilotus officinalis L.) green manure and alfalfa-bromegrass (Medicago sativa L. — Bromus inermis Leyss) hay crops do increase Olsen-P in the subsoil, possibly through root decomposition in situ. Key words: Rotations, bicarbonate-soluble Pi, legumes, green manure, fertilizers

Description: In pursuit of identifying sustainable agricultural production practices, there is an urgent need to develop or identify parameters that effectively describe and differentiate changes in the quality and quantity of soil organic matter resulting from crop management or cultural practices. The effectiveness of the potentially mineralizable nitrogen (No) concept for this purpose was examined using data from a 30-yr crop rotation study, carried out on a Rego thin Black Chernozem at Indian Head, Saskatchewan. Although Kjeldahl N and hydrolyzable soil amino-N are effective for demonstrating the beneficial influence of fertilizers, legumes and continuous cropping on total soil organic N content, they are less effective in identifying changes in organic matter quality. We have shown that a parameter which we called the "initial potential rate of N mineralization" [potentially mineralizable N (No) × rate constant (k) at time = 0] was effective in distinguishing both the absolute and qualitative changes in soil organic N due to various cultural and management practices. The results showed that fertilizers can be as effective as legumes, used either for green manure or for hay, in increasing the quantity and improving the quality of soil organic matter. A 6-yr rotation including 1 yr of fallow, 2 yr of spring wheat (Triticum aestivum L.) and 3 yr of bromegrass (Bromus inermis Leyss) and alfalfa (Medicago sativa L.) hay had a greater quantity and improved quality of soil organic N relative to that of unfertilized continuous wheat (Cont W), but they were equivalent to that of fertilized Cont W. Key words: Soil quality, potential mineralizable N, crop rotations, legumes, fertilizer effects

Description: The effects of cultivation on the net mineralization of carbon and nitrogen in a lacustrine Brown clay (Sceptre) and two Orthic Black soils on glacial till (Oxbow) were assessed with the aid of fractionation and radiocarbon dating techniques. Fractionation of the soil organic matter of comparative virgin and cultivated soils by acid hydrolysis and peptization in dilute NaOH showed that the distribution of carbon and nitrogen among fractions of these soils was similar. There was no measurable alteration in the mean residence time (MRT) of the soil during the first 15 to 20 yr of cultivation, during which time the Sceptre soil had lost 19% of its carbon and the Oxbow, 35%. However, the MRT increased from 250 yr before present (BP) to 710 years BP after 60 yr of cultivation of the Oxbow soil. The losses for nitrogen were 10% lower than for carbon in the Oxbow soil due to the recycling of nitrogen in the soil. The rate of loss of carbon from the Oxbow soil during the cultivation period was simulated by expressing it as the sum of two first order reactions using fractionation and carbon dating data as the variables.

Description: Growth chamber and laboratory studies were conducted to investigate the distribution and plant availability of copper (Cu) fractions in Saskatchewan soils. These studies included an examination of the distribution of Cu fractions in 27 soils and an evaluation of plant availability of native and added Cu fractions in beans (Phaseolus vulgaris L.) grown in seven soils. The soils in these experiments were selected to give a wide variation in physical and chemical properties. Total Cu content of the 27 soils ranged from 6.5 to 39.0 μg g−1 with an average of 21.0 μg g−1. A seven-step sequential fractionation showed that most of the total Cu (49.0–78.0%) was present in the residual fraction (Res-). The percentages of soil Cu in the exchangeable (Ex-), Pb-displaceable (Pb-), acid soluble (Aci-), Mn oxide bound (MnO-), organically associated (OM-) and Fe, Al oxide bound (FeO-) fractions averaged 2.2, 1.5, 2.0, 4.8, 7.9 and 11.1%, respectively. Amounts of Cu in MnO-, FeO-, Res- fractions and total Cu were interdependent and varied directly with DTP A- extractable Cu and clay content. The growth chamber experiment showed that the most of the applied Cu was accumulated in MnO-, OM-, FeO-, and Res- fractions. Therefore, sesquioxides and organic matter are the major components responsible for the adsorption of added Cu. The concentration of Cu and its uptake into navy beans were positively correlated with DTPA-extractable Cu, MnO-Cu, FeO-Cu and total Cu, which in turn were correlated with clay content. Plant Cu concentration and uptake can be predicted by an equation which includes DTPA-extractable Cu and clay content. These results showed that DTPA-extractable Cu is a good predictor of Cu availability in prairie soils. Key words: Cu fractions, distribution, availability, DTPA-extractable Cu, clay content, navy beans

Description: The effects of incubating monocalcium phosphate monohydrate (MCPM) with liquid hog manure (LHM) on P availability and uptake by Italian ryegrass (Lolium multiflorum Lam.) were evaluated in a 99-d growth chamber experiment. Liquid hog manure with (0.738 g P kg−1 fresh LHM) or without MCPM was aerated for a 21-d period at 24 °C. The soils used in this experiment were an Ormstown silty clay loam (Orthic Humic Podzol), and a Ste. Rosalie clay loam (Humic Podzol). Five treatments were applied to each soil: (i) control with no LHM or MCPM additions, (ii) MCPM, (iii) LHM incubated without MCPM, (iv) LHM incubated with MCPM, and (v) the separate applications of MCPM and LHM incubated without MCPM. Rates of MCPM and LHM applications were 513 kg P2O5 ha−1 and 32 t ha−1, respectively. Incubating LHM with MCPM resulted in a loss of 6% of the total manure-N during the 3-wk incubation period, compared with a 67% loss from the unamended LHM. Additions of both MCPM and LHM had the same effect on shoot-P contents and soil P fractions regardless of whether the materials had been incubated together or added to the soil separately. When compared with adding MCPM only, LHM-MCPM mixtures resulted in greater ryegrass shoot-P contents for plants growing on the Ste. Rosalie soil. However, this increase was approximately equal to the response to LHM additions, and thus presumably not due to improved MCPM P availability. Additions of both LHM and MCPM did not affect soil inorganic P forms compared with the lone addition of MCPM, but sodium hydroxide extractable organic P and sodium bicarbonate extractable organic P tended to be higher when just MCPM was added. Key words: P fractionation, liquid hog manure, manure-fertilizer mixtures, monocalcium phosphate, P uptake

Description: Wood Mountain loam was wetted with water or (NH4)2SO4 solution to provide a factorial combination among three moisture and three NH4-N levels. Samples in polyethylene bags were incubated at 2.5-cm depths in fallow, and in an incubator that simulated the diurnal patterns of temperature fluctuation recorded in the field. During the growing season, treatments were sampled regularly for moisture, NO3− and exchangeable NH4-N. Similar determinations were made on in situ samples taken in fallow Wood Mountain loam. The incubator simulated the effects of growing season temperatures on soil N transformations satisfactorily. Pronounced increases or decreases in temperature led to flushes in N mineralization. However, in the 1972 growing season, temperature was suboptimal and temperature changes were generally small. Consequently, when a stepwise multiple regression technique was used to analyze the data, neither ammonification nor nitrification showed a quantitative relationship to temperature. Comparison of the nitrification occurring in laboratory-incubated soils with that occurring in situ led to the conclusion that 70 to 90% of the NO3-N produced in surface soil resulted from wetting and drying. Estimates of potentially ammonifiable soil N(No) and its rate of mineralization (k) were derived from cumulative ammonification by assuming that the laws of first-order kinetics were applicable. In the 10, 15, and 20% moisture treatments the average No was 27, 41, and 82 ppm, respectively. Under the conditions of this study, the time required to mineralize half of No was about 7 wk.

Description: An understanding of the mineralization factors in contrasting cultivated soils is necessary for accurate predictions of plant-available N. The objective of this work was to determine the N-mineralization potential and mathematical models that can properly describe the dynamics of the mineralization process in 20 meadow soils from Quebec. The mineralization was monitored over 55.4 wk in a laboratory incubation at 20 °C with intermittent leaching. The cumulative mineralization curves in most soils were characterized by definite lags or a sigmoidal pattern and near-linear release with time after 20 wk. The data were best described by the Gompertz equation; first-order models were inadequate. The total amount of mineralizable N and the potential mineralization rate were very closely correlated with the total amounts of C or N (r 〉 0.73; P 

Description: A red clover intercrop was evaluated in terms of its ability to provide soil erosion protection and its effects on silage corn yields on a Conestoga loam soil at the Elora Research Station, Elora, Ontario. The soil and runoff losses from experimental plots of silage corn (corn system) and silage corn intercropped with red clover (corn/clover system) were compared using the Guelph Rainfall Simulator II. Measurements were made in November 1987 and October 1988, and in April, May, June of 1988 and 1989. Rainfall was applied for 10 min (15 min in June of 1988) on a 1-m2 quadrat at an intensity of 16 cm h−1. Soil loss was significantly (P 

Description: Acadia or dykeland soils have produced forages successfully for centuries. The formation of barren areas within very productive forage stands has been noted recently in some land-formed fields, indicating either poor germination or poor growing conditions. A survey was undertaken in 1988 to determine the differences in soil attributes between barren and productive areas, namely: topographical position, resistance to penetration, bulk density, pH, plant-available P2O5, -K2O, Ca, and Mg, salt content (as measured by conductivity and sodium adsorption ratio), and exchangeable and soluble Ca, Mg, K and Na. Barren areas had greater: plant-available P2O5, resistance to penetration (the differential ranged from 480 to 1440 kPa), bulk density (in the top 15 cm), salt and sodium content than the productive ones. The exchangeable and soluble Na:Mg and Na:Ca ratios were higher on barren areas than on productive areas. Organic matter content was lower on barren than on productive areas. Values for topographic position, pH, particle size classes and plant-available K2O, Ca, and Mg were similar between the productivity areas. The results of this survey indicate that the formation of barren areas appears to be mainly due to accumulation of excess salts, especially sodium. Reasons for salt accumulation in these areas are discussed. Key words: Acadia soils, dykeland, salt, sodium, organic matter, resistance to penetration

Description: Four erosion plots were monitored from 1983 to 1989 (6 yr) to evaluate the effects of two crop rotations and their constituent crops on runoff and soil loss under natural precipitation near Fort St. John in the Peace River region of British Columbia. Rotation 1 consisted of two cycles of summerfallow — canola (Brassica rapa)-barley (Hordeum vulgare L.), and Rotation 2 included summerfallow — canola-barley-barley underseed to red fescue (Festuca rubra L.)-fescue-fescue. Rainfall and snowmelt runoff were collected and sampled throughout the year to determine seasonal runoff and soil losses. Over the 6 yr, the cumulative runoff and soil losses were consistently greater under Rotation 1 than under Rotation 2. There was a greater than fourfold difference in total soil loss, and 33–35% more total runoff. Rainfall-induced runoff and soil losses were significantly higher for Rotation 1 than for Rotation 2. Snowmelt runoff accounted for 90 and 96% of the total annual runoff and for 39 and 80% of the total annual soil loss from Rotations 1 and 2, respectively. Two large rainfall events during 1983 and 1987, each causing a soil loss in excess of 2000 kg ha−1, accounted for between 85 and 91% of the 6-yr total rainfall-induced erosion from Rotation 1. No differences in runoff or soil loss were detected among crops but the comparisons were insensitive because of high residual variation. Key words: Runoff, soil loss, erosion plots, crop rotations

Description: Field studies were conducted on a Landry clay-loam soil (Black Solod) to evaluate the effects of green manuring Tangier flatpea (Lathyrus tingitanus 'Tinga'), lentil (Lens culinaris 'Indianhead') and alfalfa (Medicago sativa 'Moapa') on subsequent barley (Hordeum vulgare 'Galt') crops. Each trial consisted of separate legume phases planted in 1984, 1985 and 1986 and barley phases in each of the subsequent years. The flatpea and lentil were incorporated (green manured) in late July or in late August to early September. The alfalfa was incorporated in late August to early September. The 3-yr mean dry matter (DM) yields of lentil and Tangier flatpea varied from 1047 to 2308 kg ha−1, with considerable variability from year to year. Alfalfa, used as an annual legume, produced 812 kg DM ha−1. Dinitrogen fixation by the annual legumes, as assayed by acetylene reduction was 16 kg N ha−1 or less. Soil moisture measurements following the legumes showed 2–3 cm less water in the profile to a depth of 120 cm following alfalfa and late-incorporated Tangier flatpea than following summerfallow and early-incorporated lentil and Tangier flatpea. Ammonium-N levels in the soil were similar following the various legume green-manure treatments. Nitrate-N levels following the legumes were variable, but the levels of nitrate-N in the plots following legume incorporation generally followed the order: fallow 〉 early incorporation 〉 late incorporation. The grain and N yield of barley following early-incorporated lentil and flatpea were equal to or only slightly less than the yield following fallow, suggesting that annual legumes have a good potential as green-manure crops in place of fallow in Black Solod soils of the Peace River region. Key words: Legume plow-down, soil conservation, dinitrogen fixation, soil moisture, nitrate-N

Description: Possible sources of SO4 in soil, drift and bedrock at two saline sites in southern Alberta were investigated using sulfur and oxygen isotope analyses. Slight differences (0.6–5.2 per mil) between δ34S values of SO4 and insoluble S in the geologic material were attributed to kinetic fractionation during oxidation of organic S. Negative δ18O values of SO4 in the shallow (6 m) bedrock indicated sulfate reduction. The exact source of SO4 could not be determined in this preliminary study. The isotope approach, however, shows promise and warrants more detailed study. Key words: Salinization, sulfates, sulfur isotopes, oxygen isotopes

Description: A survey of efflorescent crusts and associated surface soils in central and southern Alberta was conducted to determine evaporite mineralogy and elemental composition. X-ray powder diffraction indicates that efflorescence mineralogies are dominated by sodium sulfate minerals, such as thenardite and mirabilite. Sodium magnesium sulfate minerals such as konyaite and bloedite are also frequently present, with eugsterite, halite and thermonatrite among other evaporites identified. The content of selected elements in the salt crusts and surface soils was determined using instrumental neutron activation analysis. Trace-element concentrations from site to site were extremely variable. However, comparisons with elemental abundances previously reported for till and soils indicate that there is generally no mean accumulation of trace elements in salt-affected soils. Exceptions are Br and Cl, which show enrichment in soils infused with soluble salts. Key words: Salinity, trace elements, evaporites, mineralogy

Description: The distribution of selenium (Se) in 54 Canadian soil profiles was examined according to horizon in the profile, and to soil properties. Apart from the organic surface layers, the Podzolic B horizons had the highest Se values (0.52 ppm), and so displayed a marked accumulation. The Luvisolic and Gleysolic B horizons also showed some accumulation. The Se content of parent materials was generally low (0.10 ppm). Simple correlation analyses of the combined data (irrespective of horizon) indicated that Se distribution was closely associated with both organic carbon and NH4-oxalate extractable Fe and Al. When the data were arranged according to genetic groupings, this association remained true only for Podzolic B horizons. Multiple regression analyses revealed that the predominant factors involved in the Se distribution were the Se content of parent materials, and the organic carbon content of the upper horizons, in that order, except for Podzolic soils. Clay had little or no influence on the Se distribution. In spite of the relationship of Se to parent materials, the contribution by atmospheric contaminants to the Se enrichment of soils could remain important.

Description: Variabilities in measured values of wet aggregate stability (WAS) of replicate samples of treatment exceeding that between treatments can create problems in interpreting treatment effects. The variabilities in WAS of replicate samples of treatment can be minimized by subjecting soil aggregates to a high vacuum fast prewetting technique. However, this technique is laborious and time consuming. In this paper the effect of four prewetting techniques: (1) and (2) high vacuum fast (HVFW) and slow (HVSW) wetting; (3) and (4) no vacuum (atmospheric) fast (NVFW) and slow wetting (NVSW) on the variations in WAS and coefficient of variation (CV) of WAS are reported. The measured values in WAS and CV of WAS for each soil varied with wetting rate and/or gas pressure used. The highest variation in WAS was found with NVFW, HVFW, NVSW and HVSW, respectively. For three out of four soils, the CV of WAS for NVSW technique was less than 2%, which was similar to that obtained under HVFW technique. Compared to HVFW technique, NVSW technique is simple, less laborious and less time consuming. Key words: Wet aggregate stability, prewetting techniques, vacuum wetting.

Description: Saskatchewan producers growing primarily spring-seeded cereals may be interested in diversifying their cropping alternatives. Winter wheat (Triticum aestivum L.) could provide one possible option, but its management could cause conflict with the busy fall and early spring activities for spring-seeded crops. A study was conducted at five sites (Swift Current, 4 yr; Melfort, 4 yr; and Scott, Lashburn, and Loon Lake, 1 yr each) in four soil zones (Brown, Dark Brown, and Black Chernozems and Gray Luvisol). The effect of time of application of N (seeding to early spring), source of N (ammonium nitrate vs. urea), and method of application (broadcast, midrow band, and seed-placed) on yield and grain protein concentration were investigated. The results varied with site and year (weather). Time of N application only influenced yields at Swift Current (Brown soil) where application on cool unfrozen soil in mid-October was as good as application in early spring and better than at other times, and application onto frozen, snow-covered soil in December was least effective. At Swift Current and Melfort, grain protein concentration did not respond to time of application; however, at Scott, Lashburn and Loon Lake, protein was highest for spring-applied N, followed by mid-October, and lowest when N was applied on frozen snow-covered soil. The effect of N source rarely affected grain yield or protein and was dependent on site and method of placement. The dangers of seed-placing N, especially urea, on overwinter survival and yields were evident in 2 yr at Swift Current. There was rarely any difference in yield or grain protein concentration when N was banded or broadcast at seeding time. Taking into account convenience of operation, the most opportune time for Saskatchewan producers involved in growing both spring and winter wheat to apply N would be mid-October in the Brown soil zone. In the other soil zones, early spring would be best. Broadcasting the N was the most appropriate method of application at all sites. Urea would be chosen over ammonium nitrate because there was little advantage of one source over the other and urea is generally cheaper. Key words: Urea, ammonium nitrate, protein, grain yields, plant population

Description: In a recent cooperative study, in which four laboratories participated, organic matter in a large number of Canadian soil samples was characterized by relatively simple methods. As result of this work we are proposing a procedure for the extraction, separation and characterization of soil organic matter. The procedure includes determinations of organic C and total N in initial soils, followed by the isolation from the soils of humic and fulvic acids. Total C and N and E4/E6 ratios are then determined in the latter fractions. From these data, proportions of extractable soil-C and soil-N and HA/FA ratios are computed.

Description: The objective of this study was to determine the magnitude of biologically immobilized and/or chemically fixed N (N retained) resulting from N addition to soils under laboratory conditions. Urea (200 μg N/g of soil) tagged with 21.0 atom % 15N was added to 11 Manitoba soils. The relationship between microbial immobilization and/or chemical fixation of added N and soil characteristics was determined using forward stepwise and multiple linear regression analyses. Three to 32 ppm of added N was immediately retained by the soils after urea was added. Biological immobilization and/or chemical fixation was virtually completed within the first 4 wk of incubation with only one soil showing continuous increase in the retention of applied N during the remainder of the experiment. Amounts of urea N retained in soils during the 12-wk incubation period ranged from 16 to 91 ppm. The initial retention of N was positively correlated with sand + silt fraction and negatively correlated the pH of the soil, the R2 value being 0.86**. Correlations between, 15N retained and organic matter (OM) content for 4 and 8 wk of incubation were positive (R2 = 0.40* and 0.53*, respectively). After the 12 wk of incubation, the retention of added N by soils was positively correlated with OM and negatively correlated with soil pH (R2 = 0.74**). The retention of N with pooled data of 4, 8 and 12 wk of incubation was positively correlated with OM and negatively correlated with both pH and CEC of the soils (R2 = 0.73**). Mineralization of soil N and retention of added N for 4, 8 and 12 wk of incubation were found to be positively correlated, the r2 values being 0.42*, 0.52* and 0.42*, respectively. Gaseous losses of applied N appeared to be appreciable in only one soil. Ten of the eleven soils showed no or little N interchange, suggesting that a significant proportion of the applied urea N appeared to be truly immobilized and/or fixed in soils.

Description: Soil respiration during the growing season was calculated from CO2 profiles in a heavy clay soil under native grass and on cultivated plots. Soil respiration of the native grass plots was correlated with moisture content and temperature of the surface soil. However, the correlation accounted for only ⅓ of the observed variation in soil respiration and could not explain the large difference between two growing seasons. Addition of mineral N decreased soil respiration and irrigation increased it. Total soil respiration on the cultivated plots was higher than on the native grassland. On the wheat plots, soil respiration was significantly correlated with soil moisture but not with temperature; the reverse was true for the fallowed plots. Soil respiration between 1 May and 1 September on the native grassland was highly correlated with rainfall and the number of days with rain in excess of 5 mm. It was concluded that the number of wetting and drying cycles in the soil was mainly responsible for the annual variation in soil respiration. From comparison with data on shoot production, it appears that soil respiration exceeds net production in wet years and that the opposite is true in dry years.

Description: Lambert sweet cherry (Prunus avium L.) established on Osoyoos loamy sand in 1983 was subjected to treatments involving all combinations of two types of irrigation (wellwater or municipal wastewater) and three rates of N fertilization (0, 68 and 136 g of N as NH4NO3 tree−1 yr−1), 1984–1987. The zero-N treatment was increased to 34 g N tree−1 in 1986–1987. Wastewater irrigation increased leaf N, P, K, B and Mn concentration, decreased leaf Mg and Ca and had few consistent effects on leaf Fe and Cu. Tree growth was increased after 2 yr but not after 5 yr by wastewater irrigation. Inadequate N and Zn nutrition appeared to limit long-term tree growth. After 5 yr, wastewater-irrigated soils had higher extractable P, K, and B and lower Ca and Mg than well-water-irrigated soils which had higher Ca and Mg to 0.9-m depth. Wastewater irrigation also increased extractable Na throughout the soil but insufficiently to adversely affect tree growth. Soil pH and electrical conductivity also increased during the experiment for both well- and wastewater-irrigated soils, but these increases did not cause alkalinity or salinity problems. Key words: Prunus avium L., wastewater irrigation, leaf nutrition, soil quality

Description: A simple power-function equation was developed to relate changes in soil 137Cs with time to an average annual soil-loss rate. The equation accounts for tillage dilution of the concentration of 137Cs in the surface plow layer and for enrichment in the eroding soil. The predictions from the relationship were similar to values for a more complicated model and to measured values given in previous studies. Key words: Erosion rate, prediction, cesium-137

Description: Potassium mine refinery dust at rates from 1.12 to 11.2 ton/ha (½ to 5 ton per, acre) was applied to a Dark Brown Chernozemic silt loam and to a Black Chernozemic loam. Under dryland farming conditions, no significant effects on yields of cereal grains have been recorded. After 5 years there is no indication that any K has moved deeper than 46 cm (18 inches). The chlorides have been removed from the surface soil and about 50% have leached to below 213 cm (7 ft). The K replaced some of the exchangeable Ca and Mg which were subsequently leached to lower depths. Much of the added K is now in the exchangeable form; some may have become fixed in the clay lattice.

Description: The impact of cultural practices on soil aggregate characteristics which determine the susceptibility of the soil to wind and water erosion was studied at two long-term (〉 30-yr) crop rotation sites on Black Chernozemic soils at Indian Head and Melfort, Saskatchewan. Surface soil (top 5 cm) taken in spring and fall, 1991, was air-dried and sieved by rotary sieve to measure aggregate size distribution. The water-stability of soil aggregates (1–2 mm) was determined after: (i) slow wetting, and (ii) fast wetting. Both rotation studies employed conventional tillage management until 1990 when the Indian Head experiment was converted to zero-tillage. Summerfallowing increased the wind-erodible (

Description: The long-term effects of wood-residue applications on soil properties are not well documented. This study was undertaken to characterize the organic matter and aggregation of a sandy loam after 9 yr of biennial application of wood residues (tree clippings) at rates of 25, 50 and 100 Mg ha−1 with and without nitrogen fertilization. Carbon (C) and nitrogen (N) contents of the whole soil were determined as well as the C content of the density fractions and of the fractions soluble and insoluble to Na4P2O7. In comparison with the control, the whole-soil C content was 16–24% higher following application of wood residues alone and 16–37% higher for application of wood residues supplemented with nitrogen. The treatments had no effect on soil water-stable macroaggregation (〉 250 μm). Wood-residue applications had no effect on the humic material (soluble in Na4P2O7) but favored the humin-C content (the fractions insoluble in Na4P2O7) by 25–60% relative to the control. The light-fraction organic matter was on average 68% larger, and the heavy fraction 17% larger, in the treated soils than in the control. On average, 80% of the differences in total organic C induced by residue application could be attributed to differences in the humin and heavy fractions. The long-term effect of wood-residue applications to the soil was, therefore, reflected in an accumulation of the more stable organic matter present as heavy and humin fractions. In addition, the differences in the light fractions suggested a short-term effect of wood-residue applications.Key words: Light and heavy fractions, wood residues, organic C, water-stable aggregates, humic acids, humins

Description: Rounding of the lands in a field involves changes in the surface horizons. The thickness of Ap horizons at various sites in corn fields varied from 15 to 41 cm. In these horizons, the organic matter content that ranged between 10 and 250 t/ha influenced the real density of the particles, the bulk density of soils with similar texture, and also the shape of the water retention curves at tensions from 0 to 1.5 MPa. Maximum available water in the Ap horizons between 33.3 kPa and 1.5 MPa varied from 0.5 to 4 cm H2O. Yield differences reached 74% while the standard deviations were generally lower than 15%. Higher yields were observed at higher, intermediate and lower sites of the fields. The differences in the yield were not entirely accounted for by the variations in the chemical and physical properties of the soils.

Description: Much forested land in the wetter zones of northern Vancouver Island is characterized by thick humus layers, with two distinct ecosystem phases: the younger "HA" phase arising from disturbance is productive after clearcutting, but in the old-growth "CH" phase, seedlings suffer growth check after 5–8 yr, with reinvasion of the ericaceous shrub salal (Gaultheria shallon Pursh.). We used solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and CuO oxidation to examine whether chemical differences in the humus might be associated with difference in forest productivity after clearcutting. NMR spectra of woody horizons, which were similar for CH and HA sites, were dominated by signals from lignin of decomposed wood. Non-woody humus types were typical of forest litter layers, and were dominated by signals in the O-alkyl region. The differences between CH and HA sites were: (i) higher tannin content in the CH sites, most likely from salal inputs and (ii) higher ratio of carbohydrate to lignin C, indicating less effective decomposition in CH sites. Oxidation with CuO also showed more advanced decomposition in the non-woody horizons of HA than of CH sites. Less effective decomposition possibly due in part to tannin accumulation could contribute to the lower forest productivity on salal-dominated CH sites in this region. Key words: 13C NMR, CuO oxidation, decomposition, humus, tannin, salal

Description: Development of Typic Haplorthods in a heathland area in Denmark responded over a short period of time (decades) to changes of vegetation. Part of the heath, Hjelm Hede, was left undisturbed and was invaded by trees, mainly oak and a few aspen and conifers. Another part of the heath was planted with Norway and Sitka spruce 60–70 yr ago. The soils under heath, oak and spruce were studied. Major differences were found, some visible in the field and others detectable in the laboratory. Under oak, relative to heath, horizon boundaries were less distinct, pH increased in the top horizons, organic carbon and C/N ratio decreased, and iron and aluminum contents in the upper B horizons decreased. Compared with the original heath podzol, the soil under spruce had a lower pH in the O, E and upper B horizons, higher organic carbon content and C/N ratio in the top horizons, increased cementation, and a placic horizon. However the pyrophosphate-extractable iron and aluminum content was significantly lower than in any of the other soils. The soil under oak showed "depodzolization" features, whereas the soil under spruce was increasingly podzolized, though the podzolization mechanism might be different from that under heath. Analyses of phenolic compounds in the soil water were consistent with these conclusions. The three main components of substituted benzoic acids were gallic acid, protocatechuic acid and coumaric acid, which are all strongly complexing agents believed to take part in the podzolization process. Generally, the highest concentrations were found under spruce and the lowest under oak.Key words: Vegetation-induced soil changes, Spodosols, phenolic compounds

Description: The concentration, contents, and distribution of nutrients, metals, and soil materials were quantified at the Howland Integrated Forest Study (HIFS) site in eastern Maine. The site is a mature, low-elevation spruce-fir forest on Podzolic soils developed from dense basal till. Standard morphologically based soil sampling and quantitative soil pits were both used to characterize the soil component of this ecosystem. Vertical trends in nutrient concentrations at the site were largely governed by the distribution of organic matter. Standard morphological soil sampling techniques tended to overestimate soil pools of labile cationic nutrients and C, and underestimate trace metals and P, as a result of underestimations of coarse fragment content. These discrepancies can be critical if extrapolations for nutrients, metals, and C are made using existing databases to regional or global scales.Key words: Forest soils, spruce-fir, quantitative pits, sample size

Description: Methane oxidation by soils is an important sink for this greenhouse gas. When tested at 50 mg L−1, the herbicide bromoxynil, the insecticide methomyl, and the nitrification inhibitor nitrapyrin inhibited methane oxidation by soil slurries. The results suggest that these chemicals might decrease methane oxidation by agricultural soils. Key words: Soil methane oxidation, inhibition, agrochemicals

Description: A loamy soil amended with sewage sludges chemically treated with Ca(OH)2, Al2(SO4)3 or FeCl3 was used for P adsorption studies. Phosphate adsorption was increased by sludge application in the order: Ca-sludge 〉〉 Al-sludge = Fe-sludge 〉 untreated soil, and was associated wtih the increase in CaCO3 and hydrous iron and aluminum oxide countents resulting from sludge application.

Description: Reduced soil water under grazing is generally attributed to reduced infiltration as livestock trampling compacts the soil surface. Grazing can also have the opposite effect on soil water through reduced evapotranspiration when vegetation is removed. On the Canadian Prairies, grazing impacts on soil water have been assessed in short-term studies but impacts of long-term grazing have not been documented. In this study, impacts of long-term grazing on soil water were assessed in mixed prairie, parkland fescue grassland, and foothills fescue grassland ecosystems of southern and central Alberta. Grazing regimes were of light to very heavy intensities, grazed early, late, and continuously during the growing season. Soil water was measured with a neutron probe to a depth of 1 m from April through October over three growing seasons. Normal patterns of soil water recharge in autumn and spring and soil water depletion in summer due to evapotranspiration were not altered by grazing. Fluctuations in soil water were most pronounced in the uppermost 30 cm but still evident in the 30- to 50-cm and 50- to 80-cm depth intervals. Heavy intensity and/or early season grazing had a greater impact on soil water than light intensity and/or late season grazing. Season of grazing affected soil water more under light than heavy grazing intensities. On most sampling dates, soil water in grazed treatments was lower than in the ungrazed control, particularly in the 30- to 50-cm and 50- to 80-cm depth intervals. Differences between the control and grazed treatments were least pronounced during the summer months with evapotranspiration depleting soil water reserves in all treatments. Key words: Soil water, grazing, rangelands, water uptake

Description: Mixtures of ammonium nitrate and ammonium polyphosphate fertilizers were used to drip fertigate Summerland McIntosh apple trees (Malus domestica Borkh.) grown on M.9 rootstocks in gravelly sandy loam. Levels of N corresponding to 25 and 50% of the recommended broadcast rate (23.5 and 47.0 g tree−1, respectively) and three levels of P (0, 17.5 and 35.0 g tree−1) were applied in a factorial randomized complete block design. Soil acidification began within 1 yr in a zone extending approximately 60 cm vertically and horizontally from the drip source. Acidification was most severe at 20–30 cm directly beneath the emitter where the soil pH decreased from 5.8 to 4.5 after 1 yr and to 3.7 after three seasons of fertigation. Rate and magnitude of pH decline were equal for both rates of N and acidification was not enhanced by the simultaneous addition of P. Calcium, Mg and K were leached to the periphery of the acidified zone. The rapid displacement of K may be of concern, particularly when NH4 forms of N are drip-fertigated in coarse-textured soils with marginal K levels. Key words: Fertigation, soil acidification, cation leaching, nitrogen fertilizer

Description: Dicyandiamide has physical, chemical and biological properties that render it suitable for use as an inhibitor of nitrification of injected anhydrous ammonia (NH3). It is readily soluble and stable in NH3 and, when applied at 15 kg/ha, it effectively inhibited nitrification of injected urea for 3 mo in soil at ca. 5 °C. These properties are relevant to the practice of fall application of NH3, with its attendant risk of loss of some of the applied nitrogen before spring sowing, as a result of nitrification.

Description: A comparative composting trial with wood shavings (WS), sawdust (SD) and peat moss (PM) was carried out under field conditions. In each, fresh material was mixed with cattle manure in a 2:1 ratio by volume. The initial pH of the WS, SD and PM composts (CST) were 6.2, 5.1 and 5.3, respectively. The chemical and biological changes in CST related to maturity were determined. Samples taken at 0, 12 and 24 mo of composting were also mixed with soil and increasing rates of N and tested as growing media for faba beans (Vicia faba L.) and corn (Zea mays L.) under greenhouse conditions. During composting, the C/N and E4/E6 values decreased in all cases but much more rapidly in WS pile. Thus, after 36 mo of composting, the C/N value decreased from 43 to 17 in WS pile and from 48 to only 35 in PM pile. As indicated by a low C/N ratio (17) and lower humic absorbance values (E4/E6 = 6.4), WS material was practically mature after 24 mo, more rapidly than SD and PM composts which presented initial lowest pH values. The microbial respiration rate (CO2), the pH and N–NO3 values increased during composting in all materials but much more in WS than in SD or PM pile. All composts were not harmful to plant growth even after a short time of composting (12 mo), but yields increased with the duration of composting. These data showed that it was possible to obtain, in field conditions, a compost from ligneous materials in 24 mo. Key words: Compost, composting, corn (Zea mays L.), faba beans (Vicia faba L.), microflora, peat moss, sawdust, wood shavings

Description: A 3-yr program was carried out in central Alberta to evaluate the immediate and residual contributions of various fertilizer sulfur sources to the pool of plant-available sulfate in soil. Three elemental sulfur products, a finely-divided suspension and two elemental sulfur + bentonite products, and ammonium sulfate were applied at various rates (0–120 kg S ha−1) in factorial arrangement with various supplemental rates of sulfate (0–40 kg S ha−1). Temporal patterns of plant-available sulfur release varied significantly among fertilizer S sources, suggesting different agronomic niches for the various forms. While ammonium sulfate and the finely divided S suspension provided almost immediate correction of S deficiency, the S-bentonite products appeared be better suited to long-term maintenance of soil S fertility. The relatively slow release of plant-available S in the latter products was attributed to ineffective dispersion of the products in the soil. These slow-release characteristics need to be considered in the formulation of fertilizer recommendations on soils previously amended with S-bentonite products. Key words: Oxidation, plant availability, residual effect, S fertilizers

Description: To better understand environmental regulation of denitrification, we examined relationships between denitrification rate and six determinant soil properties: moisture content, air-filled porosity, NO3− content, respiration rate, mineralizable-C concentration and denitrifying enzyme activity (DEA). Soil cores were collected on 27 sampling dates over a growing season at a site seeded to barley (Hordeum vulgare). Denitrification rate was measured using a static core technique and acetylene blockage. Moisture content and air-filled porosity and, to a lesser extent, mineralizable-C concentration and respiration rate were more strongly related to denitrification rate than was DEA. Denitrification rate was unrelated to NO3− content. On most sampling dates, mean denitrification rate increased substantially only below an air-filled porosity of 0.3. Moreover, the distribution of individual measurements of denitrification rate was less skewed at lower air-filled porosities. Approximately 60% of variation in mean values of denitrification rate for each sampling date could be accounted for by measurements of bulk soil properties, of which moisture content and air-filled porosity were most important. Measurements of bulk soil properties did not account for nil values of denitrification rate at low air-filled porosities or for small-scale spatial variability. Such measurements were better indicators of temporal variation — that is, when denitrification occurred — than of actual rates. Key words: Denitrification, air-filled porosity, denitrifying enzyme activity

Description: A study was made of the effects of temperature and different microorganisms, or mixtures of microorganisms, on the changes in the nitrogenous constituents of mixed forest litters (mixed pine, oak, maple) during decomposition periods of up to 4 yr at 1, 4, 10, and 27 C. The percentage of total-N in the decomposing materials increased with time, the increase being related to loss in weight of sample. The percentage of amino-N/total-N was higher with the soil-extract-treated leaf mixture than with the fungi-inoculated material; it increased to a maximum at some intermediate period, then decreased, and was highest with the 930 day 27 C material. Most of the individual amino acids increased in amount up to 930 days; then decreased, the amounts being, in general, higher with higher temperatures. Much of this increase was related to loss in weight of sample, but there appeared to be some net synthesis of amino acid. Lysine and, to a lesser extent, histidine were exceptions to this generalization. The amounts of hexosamines increased with decomposition: with the soil-extract-treated materials the increase of galactosamine was relatively greater than that of glucosamine, but little or no galactosamine was found in any of the fungi-inoculated materials. The amino acid ratios, i.e., the proportion of one relative to another, did not change in any consistent fashion, except for lysine. With the fungi-inoculated material, autoclaving reduced the amount of lysine to less than one-half and a ninhydrin-reacting material appeared before arginine on the amino acid chromatograms; its amount was not changed during decomposition. It may be similar to lysine derivatives found in acid hydrolyzates of heated milk.

Description: Three tillage treatments were evaluated over a 4-yr period for their effects on runoff and soil loss under natural precipitation on a Donnelly silt loam soil (Solonetzic Gray Luvisol) near Dawson Creek in the Peace River region of British Columbia. Conventional-tilled (CT) plots (spring or fall cultivation) received twice the amount of tillage as the reduced-tilled (RT) plots, while the zero-tilled (ZT) plots were only disturbed at seeding once a year. The plots were seeded to barley (Hordeum vulgare L.). Rainfall and snowmelt runoff were collected throughout the year to determine seasonal runoff and soil losses. The effects of the tillage treatments on runoff and soil loss depended on the season (whether caused by rainfall or snowmelt) and the crop year. Mean snowmelt runoff was ZT 〉 CT 〉 RT. Conventional tillage had significantly higher rainfall runoff and soil loss from snowmelt than the other two tillage treatments, with no significant differences between RT and ZT. Mean rainfall-induced soil loss was significantly different for each tillage treatment, with CT 〉 RT 〉 ZT. Soil losses from snowmelt were low, less than 30% of those from rainfall, since snowfall was 45% below normal. Soil losses from rainfall were consistently higher than from snowmelt for each tillage treatment in each of the four crop years and provided over 75% of the 4-yr total annual soil loss. Tillage effects were more pronounced in years with low runoff and soil loss than in years with high runoff and soil loss. Zero tillage and RT are effective in reducing average annual soil losses by 81 and 53%, respectively, of those observed under conventional tillage. Key words: Runoff, soil loss, erosion plots, seasons, tillage

Description: This study was undertaken to examine the relationship between periglacial processes and the development of soil structure in some Turbic Cryosols. Three active nonsorted pattern ground features (mud hummocks) were examined for field macrostructure and micromorphological characteristics. The surface of unvegetated mud hummocks exhibited granic fabric expressed as strong granular structure. Cryoturbic movement caused surface materials to be cycled downward toward the permafrost table and upward into the hummock core. Resultant compression caused coalescence of discrete structural units resulting in matrigranodic fabric and subangular blocky structure. Porphyroskelic fabric associated with massive and occasionally prismatic structure was observed in the core of the hummocks although some remnant granularity was evident in thin section. Cycled fragments of surface vegetation 10–1000 μm in length were observed dispersed through all soil horizons. All horizons within the active layer contained more than 2% organic carbon. Key words: Turbic Cryosol, micromorphology, soil structure, cryoturbation

Description: Growth chamber and laboratory studies of four selected soils differing in C:N:S ratios and the percentage of total S present as HI-reducible S in the soil organic matter showed that: (1) the yield response of alfalfa to applied S occurred when the 0.01 M CaCl2-extractable soil SO4—S was less than 3.3 μg/g, (2) mineralization of soil organic S was unaffected by the addition of 25 μg S/g to the soils, and (3) the amount of S mineralized was not directly related to the quantity of total S, HI-S or the percentage of total S present as Hi-reducible S. It was noted that the largest amount of S mineralized occurred from the soil with the lowest C:N:S ratios.

Description: Winter wheat (Triticum aestivum L.) can be successfully overwintered in most regions of the Canadian prairies if it is sown without prior tillage into standing stubble immediately after harvest of the previous crop. Soil nitrogen (N) is usually deficient in this production system and N fertilization is necessary to optimize yield and maintain minimum quality standards. In the present study, the effect of seed-placed (SP), early-spring broadcast (BC), and SP/BC combinations of ammonium nitrate fertilizer (AN) on winter survival, grain yield and protein production of winter wheat was investigated in 15 field trials conducted over a wide range of soil types and environmental conditions in Saskatchewan. Ammonium nitrate fertilizer placed in a 20-mm-wide band with Norstar winter wheat seed produced average grain yield responses for 34, 67, and 101 kg N ha−1 treatments that were 98, 84, and 71% of comparable BC treatments, respectively. Average grain protein yield responses for the 34, 67, and 101 kg ha−1 SP N treatments were 94, 82, and 74% of comparable BC treatments, respectively. Grain protein concentration responses were similar for comparable BC and SP N treatments. Yield responses for 34 kg N ha−1 SP and BC treatments indicated that AN could be seed-placed at low rates without significantly reducing N-use efficiency. However, significant reductions in winter survival potential in all trials where differential winterkill occurred suggested that even rates as low as 34 kg N ha−1 SP AN should be avoided when cultivars with marginal winter hardiness are utilized. Key words: Winter wheat, no-till, seed-placed N, yield, protein, winter survival

Description: In the Canadian prairie, producers generally sample soils in the autumn for nutrient analyses, whereas calibration of crop responses has been made based on soils sampled in the spring prior to seeding. A recent report suggests that available phosphorus (P) in soil increases between autumn and spring. At Swift Current, Saskatchewan, we have monitored bicarbonate-extractable P (Olsen P) every autumn and spring for the past 24 years, in four cropping systems: continuous wheat (Cont W), fallow-wheat (F-W), and two fallow-wheat-wheat (F-W-W) rotations. The first three systems received nitrogen (N) and P each crop year, with one F-W-W rotation receiving only N. These data were analyzed to test the authenticity of the aforementioned observations. We found that although there were some apparent overwinter increases in Olsen P there were also some decreases. Further, because of the considerable variability in Olsen P, relatively few of the overwinter changes were significant (P = 0.10). Efforts to correlate the changes in Olsen P to overwinter temperature or precipitation were unsuccessful. We concluded that Saskatchewan soil testing laboratories need not make adjustments to P fertilizer recommendations to account for changes in overwinter soil test P levels. Key words: Soil testing, bicarbonate-extractable P, crop rotations, available P

Description: A method to obtain relatively large portions of particle size separates from soil is described. The method was designed to minimize dilution of the soil with dispersant solution, to use simple materials and operations, and to allow fractionation of a single soil sample into a broad range of size classes. These are advantages over elutriation or batch sedimentation methods, and are important when obtaining size separates for studies of contaminant behaviour, erodable soil materials and other related topics. The method is ideally suited to study of contaminant concentrations on soil particle size separates. Key words: Sedimentation, size fractionation, clay, silt, sand, contaminants

Description: To assess the extent to which moist color value of forest mineral soils supports their differentiation according to concentrations of mineralizable and total N, 239 samples of 0–30-cm mineral-soil layers were examined for the relationship between nitrogen measures and selected categorical climatic and soil variables. The best regression models, using soil color value (SCV), climate, soil moisture and soil texture as categorical variables, explained nearly 70% of the variation in both mineralizable and total N, with climate accounting for most of the variation. The results provided support for the present usage of SCV in estimating mineralizable and total N in forest soils but suggested improvements for the development of a more effective estimation procedure. Key words: Forest soil color, soil nitrogen, climate, soil moisture, soil texture, regression analysis

Description: Field studies were conducted on Prince Edward Island (PEI) at two locations over a period of 2 years on the effect of soil and foliar applied Co on Co concentration in forages and cereals. Application of Co did not affect crop yields, although the yields varied considerably from location to location (data not reported). The Co concentration in cereal grain ranged from 10 to 25 μg kg−1 in the control plots. With foliar-applied Co, maximum Co concentrations in wheat, barley and oat grain were 101, 70 and 29 μg kg−1, respectively, in the three crops. In forages, large increases in Co were found in the first cut using foliar sprays but in the second cut the Co increases were small and significant only in one-half of the cuts. Soil applications of Co at 150 g ha−1 were ineffective in raising the grain Co but in forages Co was significantly increased in about one-third of the cuts. The mean Co concentration in forages and cereals from various fields in PEI ranged from 13 to 28 μg kg−1; such levels are considered deficient for livestock. In the case of suspected Co deficiency, 60 and 100 g Co ha−1 applied as a foliar spray to forages and cereals, respectively, should raise the feed crop Co concentration in the sufficiency range for livestock. Key words: Cobalt, wheat, barley, oats, alfalfa, timothy

Description: The capacity of soils to oxidize S was measured by incubation with finely divided elemental S in 13 calcareous orchard soils from the southern interior of British Columbia. Sulphur oxidation rates ranged from 3.4 to 26 μg S cm−2 d−1. The magnitude of pH decrease in response to added S varied inversely with initial CaCO3 content (r = − 0.58, P = 0.04) and silt content (r = − 0.64, P = 0.02) and directly with sand content (r = 0.64, P = 0.02). Incubation studies with one calcareous orchard soil indicated that finely divided S was more effective over time than other acidulants (FeSO4, Al2 (SO4)3 and H2SO4). A field study was carried out on the same soil. Finely divided and bentonitic granulated S were applied at 4.5 t ha−1 on the grass surface or incorporated to a depth of 15 cm. Incorporated fine S was oxidized to a much greater extent during a 2-yr period than was incorporated grandulated S. However, when surface applied, they were oxidized equally but slowly. Key words: S incubation, acidulating materials, S oxidation, soil pH, electrical conductivity

Description: The effect of timing of application on the recovery of fertilizer N applied to irrigated soft white wheat (Triticum aestivum L.) was investigated in a 3-yr field study and a 1-yr lysimeter study using 15N-labelled urea and ammonium nitrate. Fertilizer N treatments consisted of a check and 90 kg ha−1 applied as preplant N, postplant N or combinations. Under a controlled watering regime in the lysimeter experiment, timing of N application had no effect on plant growth parameters. In the field studies, although grain yield was not affected by N timing, grain N concentration increased from 17.9 to 19.6 g kg−1 as the proportion of postplant N was increased from 0 to 100%. Plant N uptake was greater when all of the N was applied postplant than preplant (means = 124.5 and 114.2 kg ha−1, respectively) in the field studies. Plant recovery of fertilizer N (FNR) by the difference method was greater when all of the fertilizer N was applied postplant (43.7%) man preplant (28.6%) in the field experiments. With a negative apparent added N interaction (ANI), the FNR was less by the difference method than by the 15N method. However, with a positive ANI, FNR was less by the 15N method than by the difference method. There was a greater difference between methods as the proportion of N applied as postplant N increased. Key words: Fertilizer N timing, irrigation, soft white wheat, nitrogation, fertilizer N recovery

Description: The effect of hexazinone (applied as Velpar L.) on carbon dioxide (CO2) evolution, nitrogen (N), phosphorus (P), and sulfur (S) mineralization in a surface organic layer (L–H horizons) of a forest soil was followed during a 150-d laboratory incubation. Hexazinone was applied at recommended field rates equivalent to 2 and 4 kg a.i. ha−1 and at a higher rate, 8 kg a.i. ha−1. A bioassay determined that hexazinone at 4 and 8 kg a.i. ha−1 affected the root and shoot biomass of oats for up to 63 d after application. Hexazinone had no effect on CO2 evolution, ammonification, nitrification or net S mineralization in the L–H horizons. An increase in extractable P was found in the hexazinone-treated soils at the end of the incubation. Hexazinone applied at recommended field rates of 2 and 4 kg a.i. ha−1 would have little direct impact on nutrient-cycling processes in the L–H horizons of mixed-wood cutovers. Key words: Hexazinone, carbon dioxide evolution, nitrogen, phosphorus, sulfur, forest soils

Description: The efficiency of 15N-labelled fertilizer on early harvested potaotes (Solanum tuberosum L., 'Norland') was studied in field experiments on two soil series (Saint-Damase loamy sand and Soulanges sandy loam) during a 2-yr period. The 15NH415NO3 fertilizer was band applied at 0 and 140 kg N ha−1 in 1985 and 0, 70, 140 kg ha−1 in 1986 and four harvests were made during the growing season. The foliage was in full canopy development at 65 or 75 d and its dry matter yield increased significantly with the application of fertilizer-N. At this time about 70% of the total N uptake was in the foliage. From this peak, foliage N decreased gradually with time to about 28% at 95 or 100 d as N was transferred to the tubers. The N concentration in tubers was nearly constant during the growing season. As tuber dry matter increased at each successive harvest, N uptake increased proportionally. Between the first two harvest dates, from 65 to 75 d, the average rates of N accumulation in tubers were 2.1 and 4.5 kg N ha−1 d−1 for the control and N fertilized plot, respectively. The root dry matter and N concentration increased with fertilizer-N and were generally lowest on the final harvest day. Marketable tuber yield responded to N fertilization on the severely N-deficient fields in 1985. But in 1986, the 140 kg N ha−1 treatment delayed the growth of marketable tubers. The percentage of N derived from fertilizer (Ndff) was also very high in 1985 fields and was at a maximum at 65 d (64–69%) with the 140 kg N ha−1 treatment. These values were lower for the same treatments in 1986 fields (39%) because of the larger amounts of available N in soils. The maximum coefficient of utilization (ICU) of labelled fertilizer N was 72–76% in 1985 and 63–68% in 1986. At the final harvest, about 36–50% of the applied fertilizer-N was found in the tubers. Key words: Nitrogen fertilization, 15N-labelled fertilizer, N use efficiency, harvest periods, potato

Description: Since there is little information on compound particles in the size range 2–20 μm, the genesis of the initial stages of soil aggregation was examined by transmission electron microscopy on ultrathin sections of the rhizospheres of Lolium perenne L. grown in attapulgite. Since attapulgite contains neither microorganisms nor organic matter, microorganisms were added as a soil suspension and all the organic matter was supplied by the ryegrass roots. Clusters were formed de novo by accumulation of attapulgite particles on root gel, on root cell fragments, and on microbial extracellular polysaccharides. Microaggregates were formed by the fusion of attapulgite-coated bacteria, colonies and cell remnants. Aggregates persisted after the death of the microorganisms. Key words: Microaggregates, clusters, soil ultrastructure, rhizosphere, extracellular polysaccharides

Description: 137Cs in the soil was used to estimate soil erosion at two National Soil Conservation Program benchmark sites in the province of Quebec (sites 15-QU and 16-QU). The 137Cs baseline in an uneroded forest area was approximately 3100 Bq m−2. The 137Cs content at site 15-QU ranged from 1072 Bq m−2 to 6389 Bq m−2, while at site 16-QU it ranged from 663 Bq m−2 to 5444 Bq m−2. Computed net erosion over the past 30 yr at site 15-QU varied from a loss of 9.65 kg m−2 yr−1 to a gain of 10.88 kg m−2 yr−1 and at site 16-QU from a loss of 6.38 kg m−2 yr−1 to a gain of 1.73 kg m−2 yr−1. The average net erosion rates were 2.43 kg m−2 yr−1 at site 15-QU and 1.29 kg m−2 yr−1 at site 16-QU. Soil samples collected on a grid pattern indicated that 90% and 83% of the area at sites 15-QU and 16-QU, respectively, was subjected to net soil loss. A comparison of total 137Cs movement from eroded areas to depositional areas showed that 24.2% of 137Cs was lost from site 15-QU, while about 17.6% of 137Cs was lost from site 16-QU. Mapping of 137Cs content and calculated soil loss and deposition showed that soil erosion was closely related to topography.Under similar slope conditions, the soil erosion rates were 27–68% higher at site 15-QU than at site 16-QU. Higher tillage frequency and use of silage corn were the suggested reasons for the higher soil erosion rates at site 15-QU compared with site 16-QU, which had been used for hay and small grains. Key words: 137Cs, erosion, deposition, soil conservation

Description: A soil bacterium has been isolated from field soils receiving annual applications of 2,4-D and tentatively identified as Pseudomonas testosteroni Marcus and Talalay. When added to a sprayer tank containing an aerated solution of simple mineral salts and 2,4-D amine formulations, this organism used the herbicide as a carbon source, with stoichiometric release of chloride. This system has been used to biologically degrade 2,4-D amine residues from farm operations and herbicide containers. Key words: Degradation, bacterium, residues, soil, 2,4-D

Description: Maize plants were grown in nutrient solution containing 0, 15, 30, 50 mg organic carbon L−1 of humic substances (HS) (M.W. 〈 12 KDa) extracted from a cambisol. After 14 d of growth the second and third leaves were collected and analyzed for chlorophyll and protein content and for the activities of ATP sulphurylase (ATP-s) and O-acetylserine sulphydrylase (OAS-s) to evaluate the effect of HS on maize sulphate assimilation pathway. Humic substances induced significant decreases in chlorophyll content, whereas the protein level slightly increased up to 30 mg L−1 of HS. ATP-s and OAS-s were positively affected by HS. The stimulations were different according to the enzyme and leaf investigated. Our results suggest that HS might play an important role in the efficiency of maize plants to assimilate sulphate. Key words: ATP-sulphurylase, chlorophyll, humic substances, maize, O-acetylserine sulphydrilase

Description: Field experiments were conducted for 3 yr on a Black Chernozemic soil at Melfort in northeastern Saskatchewan to determine the yield response and N uptake of seven crop/cultivars to autumn and spring applied N. The crop/cultivars were, rapeseed (Brassica napus L. 'Midas' and 'Target'; Brassica campestris L. 'Torch' and 'Echo'); wheat (Triticum aestivum L. 'Manitou'); barley (Hordeum vulgare L. 'Conquest') and flax (Linum usitatissimum L. 'Noralta') (main plots). Ammonium nitrate fertilizer treatments consisted of three rates of autumn broadcast N, 0, 34 and 67 kg N ha−1 (subplots), combined with N at 0, 11, 22, 45, 67 and 134 kg N ha−1 side-banded with seed in the spring (subsubplots). At the 67 kg N ha−1 rate, autumn application was inferior to spring application in increasing grain yield and N uptake for three of the seven crops (Torch and Echo rapeseed and Manitou wheat). Nitrogen fertilizer applied at 134 kg N ha−1 in spring produced grain yields that were not significantly higher than the split application of 67 kg N ha−1 applied in autumn and 67 kg N ha−1 applied in spring. All crops responded to spring applied N and continued to increase in yield up to the high rates of 67 or 134 kg N ha−1. Key words: Time of N application, N, crops, cultivars

Description: Field studies were conducted in Prince Edward Island (PEI) on the Fe nutrition of cereals and forages and to determine the relationship between plant Fe and soil pH. The Fe concentration in barley (Hordeum vulgare L.) and oats (Avena sativa L.) boot stage tissue (BST) and grain ranged from 35 to 65 and from 19 to 42 mg kg−1, respectively, in the control and from 38 to 57 and from 22 to 45 mg kg−1, respectively, in the soil applied Fe treatments. In the foliar applied Fe treatments, the cereal BST contained as much as 121 mg Fe kg−1 in the FeSO4.7H2O treatments and up to 86 mg kg−1 in the chelate-Fe treatment, but neither of these two sources increased Fe concentration in the grain. In the first cut of forages in the foliar treatments, the Fe was as high as 131 mg Fe kg−1, but no differences were generally found between the control and Fe treatments in the second cut. Over the soil pH ranges of 4.5–6.9, no consistency was found in the correlation coefficient (r) values between plant Fe and soil pH. In spite of the Fe concentrations as low as 19 mg kg−1 in cereal grain and 23 mg kg−1 in forages in the control treatments, no yield response to added Fe was found. However, the Fe concentrations as found in this study would be considered deficient for livestock and mineral supplements of Fe to the feeds may be desirable. Key words: Cereals, forages, soil pH, plant iron, acid soils

Description: The objective of this study was to document the effect of forest invasion on Black soils of the Aspen Parkland in Saskatchewan. A prairie-forest transition zone less than 100-m wide was studied in an upland landscape (LM) with a strong eluvial regime and a lowland landscape (WQ) where strong leaching was restricted to depressional areas. A direct count of grass opal along each transect provided evidence that forest vegetation had invaded prairie as similar amounts of grass opal occurred under forest and prairie. Soil morphology and horizon development could be related to microrelief and to site productivity as inferred from grass opal content along the transects. Forest invasion affected soils differently in the two landscapes. At LM, forest invasion was accompanied by losses of clay and organic materials as soils were progressively transformed into leached and more acidic Luvisolic soils. Eluvial and illuvial development occurring under forest were most pronounced in microdepressions and concave portions of the transect. At WQ, leached acidic soils occurred only in a depression. Forested soils outside the depression maintained high levels of organic matter and high base status comparable to adjacent prairie soils. Alteration of Black soils following migration of forest vegetation onto prairie depends on large scale physiographical effects as well as smaller scale microrelief effects. This study indicates landscape control of water movement plays a vital role in soil development and regulation of ecosystem processes. Thus, the relationship among water, soil and landscape must be considered in environmental research and environmental impact studies. Key words: Prairie-forest transition, forest invasion, Aspen Parkland, biogenic opal, soil-landscape relationships

Description: The use of inter-row ground covers has been suggested to reduce soil degradation in raspberry (Rubus idaeus L.) production. The effect after 6 yr of consistent inter-row management of ground covers or roto-tillage in raspberry on soil wet aggregate stability (WAS), bulk density, organic C and total N, and mineralizable nitrogen in the Fraser Valley of British Columbia was studied. Management treatments included no cover crop or cover crops of barley (Hordeum vulgare L.), sheep's fescue (Festuca ovina L.), perennial ryegrass (Lolium perenne L.), and white clover (Trifolium repens L.). A general pattern of perennial grasses 〉 legume and barley 〉 control was observed for soil WAS. Some quantitative and qualitative differences in the organic component of the soil profile to 30 cm were detected among management treatments. The differences were not statistically strong because the changes were small relative to the large pool present, but were relatively consistent overall. The white clover treatment tended to have more organic carbon, particularly in the subsurface, than the other treatments. The four treatments that included inter-row vegetation tended to have a greater amount of total and mineralizable N than the clean-tilled control. Crop vigour, as indicated by cane diameter, was reduced by the perennial grasses, but the inter-row management had only limited effects on berry yield. White clover appears to provide the best compromise between improving soil quality and minimizing competition with the berry crop. Key words: Wet aggregate stability, barley, sheep's fescue, perennial ryegrass, white clover

Description: Micromorphological observations, C/N values and 14C datings of organic matter were used to evaluate impacts of biological activities on the development of loose and cemented podzolic horizons of a toposequence in the St-Lawrence Lowland. In well-drained soils, the B horizons containing roots have two distinct microstructure types: (1) a microstructure with organic aggregates in root zones (

Description: Two soils from a large depressional area, one with (AL) and one without (NL) a volcanic-ash layer, were investigated to determine the effect of the ash layer on soil properties. The soil parent materials, including the ash layer, were deposited in a lacustrine environment. Both soils had well-developed A and B horizons with secondary salinity. The AL soil contained less Na in the B horizon than the NL soil, resulting in a soil classification of salinized Gleyed Solonetzic Dark Brown Chernozem at the AL site and salinized Gleyed Dark Brown Solonetz at the NL location. Saturated hydraulic conductivity and moisture retention values indicated that the volcanic-ash layer enhanced the depth of effective drainage. This was supported by greater rooting depth, weaker B horizon structure, lower salinity, and dominance of different ions in the upper solum of the AL than in the NL soil. The distribution of soluble ions in the profiles indicated that the ash layer had negligible impact on the height of capillary rise. Lower soluble ion contents in the lower profile of the AL than the NL soil were attributed to the presence of an indurated or cemented layer between the water table and the ash layer in the AL soil. Key words: Soil properties, volcanic-ash, water movement, soluble salt movement, indurated horizon

Description: not available

Description: The effects of long-term irrigation on soil salinity were studied at 13 selected sites within four major irrigation districts in southern Alberta. Of these sites, 10 have been under irrigation for over 60 yr and three for 25 yr. Soil textures ranged from sandy loam to clay. The total soluble salts in the soil profiles were either reduced or unchanged after long-term irrigation at all sites except one, which had an 11% increase but an EC of the saturation extract still less than 1 mS∙cm−1. The magnitude of reduction in soluble salts of the other soil profiles was related to the initial salt content and ranged from 0 to 82% of the original content. The SAR decreased in the subsoil at all sites. It is evident that long-term irrigation did not salinize the soils at these sites, which are considered to be representative of much of the irrigated land in this area.

Description: Potassium fertilizer requirement of rain-fed cotton was evaluated in a 3-yr field study conducted at three locations using four rates (0, 25, 50 and 75 kg∙ha−1)of K. Significant response was not obtained above 25 kg∙ha−1 applied K. Quadratic polynomials, using leaf K, exch. K, exch. (Ca + Mg)/K and applied K as independent variables, were fitted to the seed-cotton yield. As a single parameter, leaf K emerged the best predictor of yield with a coefficient of multiple determination (R2) of 86% and a corresponding regression equation of: Y (yield) = 3099.2 + 6031.6%K − 1643.3 (%K)2, followed by fertilizer K with a coefficient of multiple determination of 81% and a yield equation of: Y = 1302.3 + 53.96 app. K − 0.54 (app. K)2. Soil exch. K and (Ca + Mg)/K ratio were slightly less efficient in predicting yield giving R2 values of 0.62 and 0.76, respectively, when both the linear and quadratic terms were entered into their respective yield equations. When all the 12 possible entries (linear, and second-order terms and their square root transformations) were fed into the computer and regressed over cotton yield using a step-wise regression procedure, only two variables, leaf %K and (Ca + Mg)/K, significantly fitted the yield equation giving a predictive value of 87%. But the improvement in the precision of yield predictability as measured by the R2 value was only marginal and would not justify recommending the equation considering the extra laboratory work that will be needed to obtain the relevant variables. Critical values of 1.84% in index leaf, 0.19 meq/100 g exch. K and 50 kg∙ha−1 applied K were approximated for a maximum predicted yield range of 2440–2700 kg∙ha−1.

Description: A tubular metallic probe was built. Water and gases released into the sample chamber of the probe from the 45- to 60-cm depth could be collected in 1-min segments without exposure of the peat surface in the hole to the atmosphere. The evolved gases were identified and concentrations measured by gas chromatography. The water movement into the hole was found to vary by 3 orders of magnitude, apparently depending on whether the probe pierced a significant pocket of trapped (occluded) methane, or was close to, or away from any such pocket. It was concluded that the instrument developed would be suitable for characterizing the occurrence and movement of the gas-fluid mixture in peatland layers which would facilitate the development of new or modified mathematical models of gas and water transmission in peatlands. The study also indicated that methane, but not carbon dioxide, is occluded in the gaseous phase in amounts significant enough to influence water movement. Key words: Water movement, methane, bog

Description: Two growth chamber experiments were conducted to assess the plant availability of Zn fractions in nine Saskatchewan soils. In one experiment, two rates of Zn (0, and 5 mg kg−1) were applied to navy beans grown on seven soils ranging in pH from 6.2 to 7.8. Most of the applied Zn was recovered in Pb-displaceable and Mn oxide associated fractions after a 7-d incubation. Growth of navy bean plants was normal in all soils and treatments. Dry matter yield did not respond to Zn application. The positive correlations between amounts of Zn in exchangeable, Pb-displaceable and acetic acid soluble fractions and plant uptake indicated the importance of these Zn fractions in influencing availability of Zn. The DTPA soil test was not a successful method for prairie soils with diverse soil properties on the basis of correlations. In the second experiment, three rates of Zn (0, 5 and 10 mg kg−1) were applied to alfalfa grown on two soils with pH of 5.5 and 7.9. The total dry matter yield of alfalfa grown on the calcareous soil was increased significantly by Zn application. No yield response to added Zn was observed in the acidic soil. In both soils, applied Zn increased the Zn concentration and total Zn uptake of alfalfa significantly over the control treatment. Changes in the distribution of applied and native Zn in different fractions before seeding and at second harvest suggest that Zn taken up by plants in the calcareous soil was from exchangeable, acid soluble and possibly residual Zn. Zinc uptake by plants grown on the acid soil was from exchangeable, Pb-displaceable, acid soluble and possibly from Mn oxide associated fractions. Key words: Zn fractions, plant availability, navy beans, alfalfa, pH

Description: Pedogenesis and its effect on calcium (Ca), magnesium (Mg) and phosphorus (P) was studied on a sequence of seven Gray Luvisol soils in central Saskatchewan. The soils were formed on calcareous glacial till under trembling aspen (Populus tremuloides Michx), mixedwood (aspen and white spruce) (Picea glauca (Moench) Voss)) and coniferous (black spruce and jack pine) (Picea mariana (Mill) BSP and Pinus banksiana Lamb) forests. Soils under aspen had the highest concentration of total and exchangeable Ca and Mg in litter layers and Ae horizons, and had Ae and Bt horizons that were least acidic. The most acidic Ae and Bt horizons and lowest amounts of Ca and Mg occurred under coniferous forests, whereas the soils under mixedwood stands were intermediate. The thickness of eluvial (Ae and AB) horizons increased along the aspen to coniferous sequence. All soils had about 40% less P in their A and B horizons than was calculated to have been present at the start of soil formation. The greatest decrease in P was observed in the thickest and most acidic soil under coniferous forest. The present litter layers and vegetation make up only a small proportion of the P removed from the mineral soil. Unusually large amounts of P appear to have been translocated from A and B horizons during development of Gray Luvisols, in comparison to Chernozemic or even Podzolic soils. Our hypothesis proposes that P is ineffectively retained in the solum as P-clay-humus, or iron-P complexes and that organic P moves along with the soil water, laterally and downslope through permeable Ae horizon over less permeable Bt horizons, or vertically through macropores. Key words: Boreal forest, nutrient cycling, phosphorus losses, weathering, soil formation

Description: Growth chamber studies were conducted on the effects of placing NH4H232PO4 either in a single band below and/or to the side of the seed at rates of 10–30 kg P/ha, or with the seed at 5 kg P/ha, on growth and on uptake of soil and fertilizer P by flax (Linum usitatissimum L. ’Linott’). Two P-deficient Chernozemic soils were used; one calcareous, the other non-calcareous. On both soils, all placements of applied P significantly increased yield of flax. For all application rates, P placed 2.0 cm directly below the seed (taproot placement) was more efficient in increasing yield than P placed 1.5 cm to the side at 0.5 or 2.0 cm below the seed (shallow- and deep-side placements). The greatest yield increase occurred with taproot placement of 10 kg P/ha. Maximum yield for the deep-side placement also occurred at this rate, whereas a two- to threefold higher rate was required for maximum yield for the shallow-side placement. Only taproot placement of 10–30 kg P/ha and shallow-side placement of 30 kg P/ha gave significantly greater yields than seed placement of 5 kg P/ha. However, crop uptake of fertilizer P for all away-from-seed placements was at least double that for P banded with the seed.

Description: A micromorphological feature, termed a grain sesquosiltan, was identified in the Bf and BC horizons of some podzols in Eastern Ontario. It is suggested that the inherited or cryogenically-derived dense silasepic fabric has been gradually modified over time by weathering, illuviation and pedoturbation. This has resulted in the formation of silt/sesquioxide coatings around sand grains.

Description: In 1975, hydrated lime and calcium sulfate were applied to a Rutland gravelly sandy loam under the canopy of mature apple trees (Malus domestica Borkh. ’Spartan’) on M16 at 3000, 6000, 3 × 2000 and at 3000, 6000, 3 × 4000 kg/ha, respectively, pH and exchangeable Ca, Mg and Mn were measured in the soil sampled in 1979 at 10-cm intervals to a 60-cm depth for each of the check, 6000 kg/ha Ca(OH)2 and 12 000 kg/ha gypsum treatments. The acidity of the surface soil was decreased significantly in the 6000 kg/ha Ca(OH)2 treatment. Negligible soil Ca accumulation occurred below the surface 10-cm depth for any treatment. Soil Mn was decreased from the surface to the 20-cm level in the Ca(OH)2 treatment while soil Mg was decreased from the surface to the 30-cm level in the gypsum treatment. Fruit Ca concentration at harvest, 1975–1979 was not increased by soil Ca treatments. Leaf Mg was often reduced by soil gpysum applications in excess of 3000 kg/ha. Leaf Mn reduction did not occur until the 4th and 5th yr of the experiment in the 6000 and the 3 × 2000 kg/ha Ca(OH)2 treatments.

Description: Rapeseed grown in pots on a S-deficient soil showed little response to elemental S fertilizers applied at rates of up to 150 ppm S. The dry matter yields, percent S and N/S ratios of the aboveground material indicated severe S deficiency in the crop. A readily available S source (ammonium sulfate) at rates of 75 and 30 ppm S increased yield by three to five times over that produced by the highest rates of elemental S.

Description: Micromorphological study of Turbic Cryosols (permafrost soils) from the MacKenzie River Valley and Yukon Coastal Plain resulted in the observations of distinct unnamed fabric distributions that implied rearrangement of the skeleton grains and f-members. It was noted that the skeleton grains or f-members were capable of independent reorganization in relation to the plasma or f-matrix. Three modal fabric types were defined as follows: 1. Orbiculic fabric — The skeleton grains or f-members are reorganized into circular or ellipsoidal patterns. 2. Suscitic fabric — The skeleton grains or f-members are vertically aligned and often show an accumulation of finer matrix material at the base. 3. Conglomeric fabric — A compound distribution in which individual f-members are enclosed by finer matrix material into a secondary fabric such as fragmic or granoidic. The interpretation of the genesis of these fabrics may aid in understanding the developmental history of the soil, especially those soils that have been subjected to cryogenic processes.

Description: Terbacil in concentrations up to 500 μg∙g−1 of sandy loam soil had little effect on populations of actinomycetes, bacteria, and fungi under laboratory and field conditions during a period of 5 mo. Concentrations up to 700 μg of terbacil∙mL−1 did not affect the in vitro growth of 111 strains of agriculturally important microorganisms, including effective, parasitic, and lysogenic rhizobia from seven cross-inoculation groups, pathogenic, attenuated, and saprophytic agrobacteria, azotobacters, and other bacteria, actinomycetes, and fungi. Terbacil inhibited the respiration of total soil microbiota, of bacteria, and of fungi at all concentrations tested. By contrast, it stimulated the respiration of actinomycetes at concentrations up to 500 μg∙mL−1 and partially inhibited it at 700 μg∙mL−1. Replication of bacterial and actinomycete isolates showed minimal inhibition by the extreme concentrations.

Description: In Chernozemic soils, active CaCO3, an estimate of the CaCO3 in the clay and fine silt particles, proved to be a more effective site index for several tree species than total CaCO3. In general, active CaCO3 exceeding 7–9% caused incidences of stunted growth and chlorosis. High levels of active CaCO3 within the 0–30 cm soil depth were related to enrichment of CaCO3 in the clay fraction.

Description: The study of subsidence of organic soils requires measurements of changes in thickness of various layers in the deposit. This was achieved by drilling a bore hole to place magnetic targets at different levels. Using a fabricated detecting device, variations of thickness to 0.05 mm could be detected.

Description: A 5-yr study showed that deep plowing under irrigation is a promising reclamation procedure for Solonetzic soils containing a calcium-enriched Csk horizon within a depth to which the soil may be plowed. The liberal application of nitrogen-phosphate fertilizers on irrigated soils after deep plowing may cause leaching of calcium.

Description: Temperature was recorded at replicate locations in a rape field, both in the soil and in the crop canopy. Sources of variability in these records are examined, and the temperatures are compared with standard records from nearby meteorological stations. Variability within replicates depends on elevation, reaching a maximum at a soil depth of 5 cm. Temperatures in the soil of the rape field were more extreme than those recorded under sod at a nearby meteorological station, though the differences were small when a full rape canopy was present. Removal of the canopy at harvest caused wide diurnal fluctuations and an increase in the average daily maximum at all crop elevations, though temperatures recorded at a nearby meteorological station were similar before and after harvest. Linear regression equations are provided that estimate daily maximum and minimum temperatures in the soil of the rape field to a depth of 20 cm from standard meteorological records.