ALBERT

Beschreibung: 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

Beschreibung: 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

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Beschreibung: 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.

Beschreibung: 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

Beschreibung: 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.

Beschreibung: 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).

Beschreibung: 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.

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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.

Beschreibung: 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

Beschreibung: 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.

Beschreibung: 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 

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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.

Beschreibung: 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.

Beschreibung: 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

Beschreibung: 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.

Beschreibung: 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 (

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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.

Beschreibung: 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

Beschreibung: 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.

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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

Beschreibung: 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