ALBERT

Description: In a previous study a nitrogen mineralization model was developed by combining the potentially mineralizable nitrogen (No) with functions representing the effect of temperature and soil moisture on the mineralization rate constant (k). The model performed well in predicting the amount of net nitrogen mineralized during a growing season when soil was incubated in plastic bags placed in incubators or buried in the field. In the present study a similar model was used to estimate net nitrogen mineralized in situ from Wood Mountain loam an Orthic Brown soil at Swift Current, Saskatchewan under (a) summerfallow, (b) cropped-dryland and (c) cropped-irrigated conditions. Model output showed good agreement to field measurements especially for the first 45–60 d, but thereafter tended to underestimate the measured data particularly under cropped-dryland conditions. During a growing season the cropped-irrigated system predicted 69 kg ha−1 net nitrogen mineralized, but 81 kg ha−1 was measured; the corresponding values for summerfallow were 64 and 86 kg ha−1, and for cropped-dryland 36 and 52 kg ha−1, respectively. The model is not dynamic since it does not allow for No to be replenished continuously by nitrogen derived from decomposition of fresh residues and rhizosphere microbial biomass. Net nitrogen mineralized from this source might explain at least part of the underestimate predicted by the model. Other sources of possible discrepancy could be imprecision in measuring the mineralization of nitrogen and in estimating the parameters in the model. Nonetheless, it was established that one of the main shortcomings of the model was that it underestimated the amount of nitrogen mineralized whenever the soil became very dry and was then rewetted by rainfall. This was probably because the latter process resulted in large flushes in mineral nitrogen in situ while in the laboratory estimate of No and k, this effect is not adequately simulated. Key words: Q10, No, N mineralization, rate constant, temperature function

Description: The influence of tillage on net nitrogen mineralization out of sod for two toposequences was estimated by several different methods. A field procedure utilizing small rain shelters to prevent leaching was employed to measure N mineralized in no-tillage (NT) and plowed (CT) treatments for six soils. Potentially mineralizable N and autoclavable N were also determined. An intact soil core procedure was developed to measure N mineralization. With the field procedure, mineralized N was generally greater in the well-drained soils but decreased with decreasing drainage. There was a highly significant interaction between soil type and tillage with greater amounts of N mineralized in the plowed well-drained soils but less in the poorly drained soils when compared to the corresponding no-tillage treatment. The standard laboratory estimates were able to predict differences between soils but did not predict the tillage effect. The development of a laboratory intact core procedure allowed for simulation of tillage effects and was correlated to the field estimates (r = 0.76). More importantly, the tillage ratios for mineralized N (NT:CT), which varied from 1.38 to 0.43, were reasonably correlated (r = 0.73) between the field and intact core procedures. Key words: Mineralized N methods, no-tillage, moldboard plow tillage, intact cores

Description: A survey of the DTPA-extractable Cu levels of approximately 1000 fields representing a large number of soil types in Saskatchewan suggested that, under current cropping systems, Cu deficiencies appear to be concentrated in the Grey Soil Zone. They are especially probable in seven soil associations, which include light Transition of Grey and Brownish-Grey Podzolic soils. Soil criteria for detecting Cu deficiencies in cereal crops cannot be fully documented using conventional calibration tests and techniques. However, data from 21 field trials and a growth chamber study indicated that the critical level of DTPA-extractable Cu in these soils is approximately 0.4 mg∙kg−1 for cereals. Large spatial variability of DTPA-extractable Cu levels has been found to occur in a level field, thus suggesting that the Cu status of a field may not be adequately described by assessing the Cu levels of composite field samples. Key words: DTPA-extractable Cu, soil survey, critical level, spatial variability

Description: The objective of this study was to compare several methods of estimating the availability of soil nitrogen to plants. Total soil N, organic matter content, mineralized N during a 2 wk incubation at 35 °C, organic N in 6 N HC1, 0.01 M NaHCO3 and 1 N KCl extracts, and finally mineral N extracted by 2 N KCl were evaluated and contrasted with N uptake by sugar beets cultivated on 19 soils in a greenhouse experiment. The relative yield or plant N uptake gave the highest correlation coefficients when both mineral and organic N fractions in soil extract were considered. The incubation methods gave the best correlation coefficient with relative yield (R2 = 0.85**). N contents in NaHCO3 extract were more correlated with relative yield or N uptake than total N, organic matter contents or N extracted by 6 N HCl or 1 N KCl. The UV absorbance values obtained at 205 nm with 0.01 M NaHCO3 extract were also well correlated with relative yield (R2 = 0.78**) and plant N uptake (R2 = 0.66**). At this wavelength, as well as at 220 nm, the absorbance was affected by mineral and organic N contents in the extract. However, at 260 nm, the UV absorbance was only related to organic N in the extract; consequently these absorbance values were less correlated with relative yield (R2 = 0.49**) or N uptake (R2 = 0.27*). Furthermore, the absorbance measured at 205 nm was too sensitive to NO3-N and organic N concentration and this relationship was not linear in the high-N concentration range. The UV absorbance at 220 nm in the 0.01M NaHCO3 extract seemed to be a promising method to evaluate the availability of soil N. Key words: Soil nitrogen, incubation, ultraviolet absorbance, hydrolyzable nitrogen

Description: A 7-yr study was conducted to determine the effects of repeated annual applications of manure containing softwood shavings (M + S) at 50 t ha−1 on the soil and its productivity, relative to manure without shavings (M) at 50 t ha−1 and nitrogen fertilizer (F) at 67 kg ha−1. The EC, OM, total N and C:N ratio of the soil of the M + S and M + S + F plots to 60-cm depth were not significantly greater than those from the M plots, and in some instances they were significantly less. The NO3-N and total N and available P contents of the soil from the M + S treatment were significantly lower than those from the M treatment. Immobilization of N in the M + S and M + S + F treatments was indicated. Barley (Hordeum vulgare L. 'Gait') straw and grain yields and protein content of the grain were generally greater under the M than under the M + S treatment. When N fertilizer was included in the M + S treatment (M + S + F) the yields were similar to those of M, and the protein content increased. If manure with shavings is used for fertilizer, supplemental N should be applied to offset N immobilization. Key words: Manure disposal, manure, manure with wood shavings, nitrogen, crop yields

Description: Palaeosols may: be found in almost every stream valley in southern Alberta. Humic acids from Ah horizons of palaeosols from five locations were examined by infrared spectroscopy, and the percentage of opal phytoliths in the coarse silt (20 to 50 μ) fraction was determined.The combination of the character of the infrared spectra of humic acids and opal phytolith counts was helpful in explaining the genesis of the palaeosols of the five locations. Sometimes the presence or absence of evidence of human occupation will add to the interpretation. In the locations examined, grasslands apparently have been dominant during post-glacial times with invasions of trees, such as Populus spp. and Salix spp., in the moister and more sheltered riparian habitats in this area. Any of these invasions naturally led to a transformation of these grassland soils.

Description: Free iron determined after extraction by acid ammonium oxalate was found to be abnormally high in various horizons of two Quebec soils containing magnetite, namely: an Orthic Humic Podzol (Pikauba series) and an Orthic Regosol (Malbaie series). When magnetite was removed, prior to the analysis, truer values for free amorphous sesquioxides of iron and aluminum were obtained and could serve to distinguish Podzolic from other classes of soils. The calculated pH-dependent cation exchange capacities were not affected by the presence of magnetite in soils. This last criterion, together with pH in CaCl2, exchangeable aluminum and degree of base saturation, can well serve as a substitute for differentiating Spodic B horizons from other horizons as used in the Canadian taxonomic classification of soils.

Description: The thermal stability and acidic characteristics of Al interlayered montmorillonite were affected by citric acid which was present during its formation. Perturbation to the formation of Al interlayers by citric acid resulted in more gradual loss of their structural water in the 430 °C to 520 °C region at initial citric acid/Al molar ratios of 0.1 and 0.5. The data clearly reveal that, besides hydroxy-Al polymers, hydroxy-Al-citrate complexes adsorbed on the surfaces of montmorillonite very substantially contribute to the total and third buffer range titratable acidity of the clay. Key words: Hydroxy-Al-citrate interlayers, smectite, organic acid, DTA, third buffer range, organic carbon

Description: To investigate the content of amorphous forms of Fe, Al and Si in podzolic soils, the B horizons from 54 Humo-Ferric Podzols and 24 Eluviated Dystric Brunisols were sampled in northern Ontario. Dithionite-citrate-bicarbonate (DCB) Fed and Ald, acid NH4-oxalate Feo, Alo and Sio, Na-pyrophosphate Fep, Alp and Cp and NaOH-tetraborate Fet and Alt were determined on all samples. Feo/Fed ratios averaged 0.87 and suggested that most of the extractable Fe was amorphous. Inorganically bound Fe and Al in pyrophosphate extracts were estimated by addition of NH4OH to the extracts. The amount of inorganically bound Fe, expressed as a percentage of that extracted by DCB, was calculated at 79 ± 23%, whereas the corresponding value for Al was 61 ± 20%. (Alo-Alp)/Sio atomic ratios, plus linear correlation analysis of (Alo-Alp) against Sio, suggested the presence of amorphous aluminosilicates with Al/Si ratios approaching 3. (Feorg + Alorg)/Cp ratios averaged 0.10, a figure near the value suggested by other authors for the maximum amount of Fe and Al bound to organic matter. (Cp/(Fep + Alp) atomic ratios did not appear to be useful in differentiating Podzolic from Brunisolic soils. Key words: Podzolic soils, chemical criteria, extractants

Description: In two 3-year cycles of a field experiment annual N treatments were superimposed on mineral treatments applied annually and triennially to a permanent pasture sward.Applications of P and K were reflected by changes in exchangeable K and acid-soluble plus adsorbed P. There was somewhat greater penetration of K than of P and soil levels of both were generally lowest where rate of N application was highest.Yields varied from year to year but tended to be more uniform with annual than with triennial mineral treatments. In the 6-year period average yields for all 0-, P-, K-, and P–K-treated plots were approximately 1.3, 1.6, 1.5, and 2.0 tons per acre of dry matter. Time of nitrogen application had little influence on total yield but seasonal distribution of herbage was much more uniform with nitrogen applied in summer than in spring. Soil moisture, which was a major factor in the response obtained with nitrogen applied in summer, was limiting during the late summer in two of the three years measured.Percentages of P and K in grass reflected the mineral treatments which had much less influence on botanical composition and species foliage cover than N. This element suppressed legumes, increased grass, and markedly influenced the K level in grass.

Description: The accuracy of evapotranspiration (E.T.) determinations by the neutron scattering method was found by studying each of the possible errors. For the gravelly soils studied the probable error in E.T. was less than 0.15 in. of water for a weekly period and less than 0.62 in. for a 3-month period when one sampling site was used. Increasing the number of sampling sites decreased the error but not in direct proportion. The method was used to provide values for evapotranspiration from irrigated and unirrigated corn, wheat, and clover.

Description: not available

Description: Organic matter and nitrogen content of a Black lacustrine clay soil at Winnipeg was maintained at a high level by intensive cropping to cereal grains. Frequent fallowing resulted in the greatest decline in soil organic matter.Yields after fallow were greater than yields of second or third crop, but greatest production per hectare per year was obtained by continuous cropping. Barn manure applications reduced the rate of decline of soil organic matter and nitrogen, and increased crop yields. Application of monoammonium phosphate did not affect soil organic matter or nitrogen, but increased yields slightly.Barley produced the most grain, oats second and wheat the least when they were grown in continuous monoculture for 37 years.

Description: Subsoil moisture accumulation due to cultivation and particularly summerfallowing is considered as an important causative agent of dryland salinity. However, few studies have been conducted to quantify the magnitude of this accumulation. The amount of additional moisture that had accumulated under cultivated land as compared to adjacent native prairie was determined at two sites in Southern Alberta. In comparison to noncultivated sites, a total of 74.0 cm of additional moisture was found under the cultivated area of a Dark Brown Chernozem and 36.2 cm under a Brown Chernozem to a depth of 6 m. Only relatively insignificant changes in salt content were found. Key words: Dryland salinity, soil moisture, soluble salts

Description: Repeated freezing and thawing of glacial till cores of clay loam texture results in the formation of granic and metafragmic microfabrics. These units of fabric are best developed near the surface of cores kept at moisture levels between field capacity and saturation. Well-sorted lacustrine sediments with fewer voids tend to form banded fabrics. Many of the morphological features such as vesicles, metavughs and desiccation cracks commonly attributed to freeze-thaw processes are evident in all materials tested. Discrete units of fabric observed in this study are very similar to units of fabric observed in the Ah horizons of Black Chernozemic and Cryosolic soils. Results of this investigation strongly support earlier research which suggests that frost processes are major contributors to their microstructural development. Key words: Granic, freeze-thaw, microfabrics

Description: not available

Description: The presence of bands in the lower sola has presented difficulties in the classification of soils developed from pitted deltaic sandy parent materials west of Edmonton, Alberta. The bands were shown to contain more organic matter, free iron, and clay than the interbands, which resulted in a darker, redder color and finer texture as observed in the field. The bands were often coincidental with stratified layers, but their occasional transgression across geologic stratification and their development in profiles without stratification suggested a pedogenic origin. Micropedological investigations revealed oriented clay around the sand grains in the bands and not the interbands, further indicating that the increase in clay was due, at least in part, to illuviation.The bands in the soils investigated have sufficient total thickness of clay accumulation to meet the requirements for a Bt horizon and together with their chemical, physical, and mineralogical characteristics permit their inclusion in the Eluviated Dark Grey Subgroup of the Chernozemic Order and the Orthic Dark Grey Wooded Subgroup of the Podzolic Order.

Description: not available

Description: When P32 and Fe59 were added to the surface horizons of a Podzol, a Brown Podzolic, and a Gray Brown Podzolic soil, it was found upon leaching of the profiles with Na2–EDTA in the laboratory that the movement of Fe was much greater than that of P.Of the added P32, 97% was leached from the A2 horizon of the Podzol as compared with only 8 to 9% from the corresponding horizon of the other two soils. In the Podzol, there were similar rates of release of native P and P32 throughout the leaching period.The movement of P and Fe was found to be associated in the Podzol and Gray Brown Podzolic but not in the Brown Podzolic profile.

Description: The compactability of normal and saline–alkali samples of Hatton loam, Haverhill loam, Sceptre clay, and Sceptre heavy clay was determined in the laboratory. Their soluble salt and organic matter contents were related to aggregation of soil particles. Well-aggregated samples resisted compaction and maintained a larger volume of pore space when subjected to vertical loads.In saline–alkali soils the liquid and plastic limits were lower, less water was held at the [Formula: see text] and 15 atm tensions, and the hydraulic conductivity was substantially less than that of normal soils. Resistance of a soil to compaction and dispersion was influenced strongly by its aggregation, organic matter, and soluble salt content.

Description: Experiments at seven locations in Western Canada between 1956 and 1961 indicated that three or four tillage operations were usually enough for satisfactory weed control on summerfallow, and generally provided highest yields of grain. Two tillage operations were not sufficient. The herbicides that were available did not control all of the weeds that were present. Nitrate nitrogen accumulation at the end of the summerfallow period was greater when weeds were adequately controlled by tillage than with incomplete control. Different amounts of tillage had little effect on soil-moisture conservation. The use of herbicides without tillage resulted in inadequate weed control in most years, and slightly less moisture was stored.

Description: Experiments were started in 1945 to study the effectiveness of various rates of monoammonium phosphate and barnyard manure for wheat production on an Indian Head clay Chernozem. The yield data indicate that the various long-term treatments have changed the relative yield potential of their respective plots. Over the years, the responses of wheat to the various treatments have changed, with the higher rates of amendments giving progressively higher yield increases while the lower rates have given less significant yield increases. Soil tests and 'A' value data from subplots show that the plots which had high rates of amendments have phosphorus values much higher than the plots which received no amendments. The use of moderate rates of monoammonium phosphate for the past 20 years has maintained the phosphorus fertility of the Indian Head soil near an optimum level.

Description: not available

Description: Twenty organic-soil samples of widely differing degrees of decomposition were extracted with 0.5 N NaOH solution under N2. Amounts of humic and of fulvic acids in the acidified extracts did not correlate significantly with pyrophosphate solubilities. This was thought to be due to interference in the separation scheme by relatively large amounts of ash constituents in the extracts. Since the "classical" fractionation of soil organic matter appears to involve essentially the "salting out" of higher molecular-weight humic from lower molecular-weight fulvic acids, an excessively high salt concentration during the separation should be avoided.To lower the concentration of inorganic constituents in the extracts, the samples were first pretreated with dilute HCl–HF solution and then extracted with 0.1 N NaOH rather than with 0.5 N NaOH. Under these conditions, amounts of fulvic acids in the acidified extracts showed a significant positive correlation (r = 0.52) with pyrophosphate solubilities of untreated extracts, whereas amounts of humic acids in the extracts exhibited a highly negative correlation (r = −0.57) with pyrophosphate solubilities. In the soils examined, increased humification was associated with increases in fulvic-acid but decreases in humic-acid concentrations.From the results of this and of earlier investigations done in this laboratory it appeared that the main mechanism governing humification in these soils was oxidative degradation, resulting ultimately in the formation of fulvic from humic acid.

Description: not available

Description: not available

Description: Response of spring wheat (Triticum aestivum) to varied amounts of broadcast and band-applied phosphorus (P) was examined at soil temperatures of 10, 15, 20 and 25 °C. The research emphasized the response of shoot yields with time and the root proliferation in the band-applied P. A non-destructive technique to measure growth with time was developed. This method allowed interpretation of plant responses even though the temperature treatments markedly changed the rate of physiological development. The relative plant-shoot response to P application did not change with time or developmental stage in this experiment. There was a marked effect of temperature on plant response to band-applied P. Band application was more efficient than broadcast P at 10 °C soil temperature, but less efficient at 25 °C soil temperature. Root proliferation in the fertilizer band was significantly different from the control soil-zone only at 10 °C and was not diminished by concurrent application of broadcast P. The efficiency of band application was confirmed with 32P labelling of the banded P. Banded P accounted for more of the total plant P at lower soil temperatures than at higher soil temperatures, regardless of concurrent application of broadcast P. Temperature had little effect on yield response to broadcast P at the final sampling or throughout the growth period. Tissue P concentrations decreased with increases in temperature and with time. Key words: Temperature, root proliferation, band, broadcast, phosphorus

Description: Annual applications of ammonium nitrate (449 and 898 kg/ha) were added to bromegrass growing on a Black Solonetz soil. Over a five-year period the average yield per year was 1,506 kg/ha on the check plots, 4,794 kg/ha on the plots receiving the 150-kg rate of nitrogen, and 6,779 kg/ha on the plots receiving the 300-kg rate.The nitrogen and potassium content of the bromegrass was increased from deficiency amounts on the check plots to sufficiency amounts on the fertilized plots- the sodium, aluminum, and iron content of the grass was somewhat reduced There was a significant reduction in soluble and exchangeable sodium in the A horizon of the fertilized soil as compared with the check. This, plus the greater growth of roots and the accumulation of nitrates in the subsoil of the fertilized soil, suggests a greater permeability in the fertilized plots. Supplementary experiments on Dark Brown Solonetz soils gave results similar to those obtained on the more humid Black Solonetz.

Description: The Cs-137 concentration of oats grown in peat in the greenhouse was affected only slightly by liming. The values were considerably higher than those obtained when mineral soils were used. The effect of different levels of soil organic matter on Cs-137 concentration in oats and alfalfa was obscured by variable exchangeable soil-K contents. But high Cs-137 concentrations were associated with high organic-matter contents provided K was added to the soils. In contrast to the results obtained with oats, the Cs-137 concentration in lettuce grown after oats was found to decrease with increase in soil organic-matter content. It was concluded that the effect of organic matter on the Cs-137 concentration in the second or subsequent crop in a rotation might be different from its effect in the first crop.

Description: not available

Description: Soil samples taken from a Podzol Bh horizon were extracted with NaOH solutions, ranging in concentrations from 0.05 to 1.0 N. The highest proportions of soil C, N, Al2O3, Fe2O3, SiO2 K2O, and P2O5 were extracted by 0.1 and 0.15 N NaOH solutions.Following extraction, aliquots of each extract were passed over H-resin. The ash contents of purified extracts were as follows: 0.05 N NaOH = 27%; 0.1 N NaOH = 17%; 0.15 N NaOH = 13%; 0.25 N NaOH = 7%; 0.35 N NaOH and higher = 

Description: not available

Description: not available

Description: Residual effects of fertilizer on native grassland throughout southwestern Saskatchewan persisted for six years or more, and were more important than the initial response. These residual effects resulted in yield increases and in increased phosphorus content of the forage. The sodium bicarbonate-extractable (available) phosphorus in the soil was increased by the use of phosphatic fertilizer; this increase persisted for six years after fertilizer application. The correlation coefficients between yield response and measured soil properties were not high for any of the measurements. The yield response was more closely related to the amounts of available N in the soil, the pH, and the texture than to the other soil and plant measurements. Responses were greatest on medium-textured soils, low in fertility and with a pH above 7.

Description: Results of a 9-year (1956–1964) series of N–P–K factorial fertilizer experiments carried out in a three-year rotation at "Les Buissons" station in Saguenay county, Quebec, are presented. Yields and quality of tubers were recorded and levels of available P and K in the treated plots, at the end of the experiment, were compared with those in the control plots.The need for nitrogen at the beginning was over 100 kg/ha; nevertheless, the optimum level appeared to be about 90 kg/ha for subsequent applications. Phosphorus seemed to be the critical element, even the maximum application of 80 kg/ha (P) being insufficient to supply its deficiency in the soil. Although the amount of available P in the treated plots increased by 19 kg/ha during the experiment, this soil requires a basic application of about 100–120 kg/ha of the element. Since the effect of nitrogen is limited by a lack of phosphorus, a proper ratio is recommended for these elements. Application of 80 kg/ha of potassium is needed for the first rotation but, thereafter, a maintenance application of 60 kg/ha should be enough for good yields of tubers of satisfactory quality. Application of 148 kg/ha of potassium was followed by an increase of 58 kg/ha in the level of available K.

Description: Reactions between phosphate, Al and Wyoming bentonite in aqueous suspensions were studied under two conditions: (1) H3PO4 was added after interlayer hydroxy aluminum complexes had been formed by the addition of Ca(OH)2 to AlCl3 + bentonite suspensions; and (2) H3PO4 was added to AlCl3 + bentonite suspensions before the addition of Ca(OH)2. The suspensions were aerated and maintained at 25 °C.When H3PO4 was added after the formation of hydroxy aluminum complexes, the results were not significantly different from those when Ca(OH)2 was added to suspensions containing both AlCl3 and H3PO4. Phosphate was removed from solution and an interlayer hydrous aluminum phosphate was formed which increased the d(001) spacings of the bentonite. The amount of phosphate removed from solution increased to a maximum with increasing amounts of H3PO4 added and over this range there was no change in cation exchange capacity (CEC). Large amounts of H3PO4 increased the CEC of the bentonite. A major part of the reaction was completed within 24 hours and the values of pH changed only slightly from 1 to 120 days.Values of the (Al) (OH)2(H2PO4) ion product measured after aging for 14 days were larger than would have been maintained by crystalline variscite, but X-ray diffraction studies showed no evidence for formation of a separate crystalline phosphate phase.

Description: not available

Description: Ammonium applied alone or after addition of K depressed the uptake of K by oats grown in a sandy loam soil in the greenhouse. When NH4 was added first and K later at seeding, however, NH4 increased K-uptake.In the absence of K fertilizer, NH4 reduced the release of non-exchangeable K to the plants. When added prior to or at the same time as K at seeding, NH4 reduced K-fixation. This inhibitory effect of NH4 on fixation of added K was reflected in higher amounts of K in solution as shown by lower [Formula: see text] ratios. These results of chemical extraction of the soil indicated that the effects of NH4 on K-uptake by the oat crop arose from reactions in the soil.

Description: Initial nitrate-nitrogen content of the soil gave a correlation coefficient (r) of 0.93 with yields and with total nitrogen uptake of Brussels sprouts plants (Brassica oleracea var. gemmifera DC., Jade Cross). Soil nitrogen extracted with 0.01 M NaHCO3 gave r values of 0.76 with yields and 0.75 with nitrogen uptake. Nitrate incubation results from leached, moist soil samples gave r values of 0.59 with yields and 0.56 with nitrogen uptake. However, air-drying of soil samples prior to leaching and incubation resulted in r values of only 0.15 and 0.11 with yields and nitrogen uptake, respectively. Available nitrogen determined by incubation without previous leaching of the soil samples gave high r values because of the influence of the initial nitrate nitrogen in the soil.

Description: Field and laboratory trials were used in attempts to relate soil moisture tension and the efficiency of a silt loam soil to oxidize the organic material in cannery corn waste. The organic loading in the waste was expressed as chemical oxygen demand (COD). Evidence was obtained to indicate that the back fill over the field tiles had not settled adequately and the waste was not retained long enough by the soil to facilitate oxidation. With laboratory trials using the miscible displacement technique, 97% of the COD was removed at soil moisture tensions of 45 and 100 cm of water.

Description: Experiments were made to determine the relative amounts of solid phase hydroxyaluminum to polynuclear ionic hydroxyaluminum formed, according to methods developed by one of the authors, during titrations of dilute AlCl3 solutions with a base. With both 10−3 and 10−2 M AlCl3 solutions, and with both fast (less than 5 minutes) and slow (12 hours) titrations, the solid phase and the polynuclear ions were present at each degree of neutralization at which measurements were made. During the greater part of the titrations the solid phase was the major product with the fast titrations, and the polynuclear ions were the major product with the slow titrations. Beyond about 80% neutralization the polynuclear ions began to decrease in concentration until at 100% the solid phase approached 100% of the products regardless of the rate of titration. There was a considerable amount of Cl associated with the solid phase during most of each titration, but the Cl/Al molar ratio of the solid approached zero as neutralization approached 100%.

Description: Two foliar applications of 6.00 or 9.00 kg/ha of MnSO4 (from MnSO4∙H2O) on flue-cured tobacco, grown on a Fox sandy loam low in available Mn, increased the Mn content of green and cured leaves but did not affect the levels of Fe and Cu.In greenhouse experiments with the same soil, applications of 120 kg/ha MnSO4, with and without S or superphosphate, raised the Mn content of oats and leaves and stalks of tobacco. Sulfur applied at 1122 kg/ha, with or without MnSO4, raised the Mn content of oats and tobacco and lowered the pH of the soil. Applications of 978 kg/ha P (from 20% superphosphate), with or without MnSO4, lowered the soil pH and increased the Mn content of oats; in conjunction with the high, rate of MnSO4, applied P raised the Mn content of tobacco stalks and top leaves. Apparently the enhancement of Mn uptake by the application of S or superphosphate is due to the decrease in soil pH.

Description: not available

Description: Water containing 0.1 N ammonium or divalent cations penetrated a sodic soil upwards of 50 times as fast as water alone. Infiltration of water applied to a Duagh soil treated with these solutions varied from 41 to 51 mm/hr, but decreased with time. A field application of these cations could thus cause the sodium to move farther down the profile with periodic rainfall. Calculations showed that diffusion of Ca++ into a sodic soil in the absence of viscous flow will not contribute significantly to reclamation of sodic soils.

Description: Repeated sampling at a single location on each of three soil types at irregular intervals during the 12-year period 1955–1967 indicated a highly monthly and yearly variation in the percentage of the total soil in aggregates 〈 0.84 mm in diameter (the erodible fraction) by dry-sieve analysis. The greatest degree of variation occurred in the clay soil. Increases and decreases in aggregation were correlated among soils.The amount of the erodible fraction determined by dry-sieve analysis is highly dependent on the date of sampling. Consequently, the value of dry sieving as a method of predicting the susceptibility of soils to wind erosion over an extended period of time is limited.

Description: Identification of nutritional disorders in crops growing on saline soils may facilitate the development of breeding or agronomic practices that improve yields in saline areas. An investigation was conducted under controlled environment conditions to identify possible cation deficiencies in barley (Hordeum vulgare 'Gait') grown under sulfate-dominated salinity stress. Soil was artificially salinized to produce a factorial of five salinity levels (ranging from approximately 6.5 to 17.5 dS m−1) and five salt types containing various ratios of Na:Mg:Ca. A control treatment (3.1 dS m−1) was also included. Barley was grown for 75 d and harvested for analysis of dry matter yield and tissue composition. Yield response of barley to salinity stress was not differentially affected by the type of salt used in salinization. Concentrations of sodium and magnesium in the plant tissue were generally increased by salinity stress, but these accumulations did not restrict yield since no consistent relationship was found between the concentrations of these cations and barley yield. Potassium concentration in the plants was inversely related to level of soil salinity, apparently because of an antagonistic effect of sodium, but was not consistently related to barley dry matter yield. Calcium uptake was also suppressed by soil salinity. In contrast to the results observed for other cations, a very strong relationship indicative of a yield response curve was observed between yield and calcium concentration in the plant tissue, particularly when the latter was expressed as a ratio of total cation concentration (R2 = 0.94). Furthermore, calcium concentration in the plant tissue and estimated calcium activity in the soil solution in highly salinized treatments were well below those considered adequate. These results suggest that calcium deficiency may have played an important role in restricting yield under salinity stress. The apparent calcium deficiency induced by salinity stress was attributed to reduced activity of calcium in the soil solution because of precipitation with sulfate and high ionic strength. Key words: Calcium, magnesium, potassium, sodium, salinity

Description: Quantification of calcium carbonates in a light-colored matrix or disseminated calcium carbonates cannot be obtained directly from impregnated blocks by image analysis. A method that combined staining by alizarin red-S with digital image analysis made it possible to identify and quantify soil calcium carbonates including the disseminated form in thin sections. Best results were obtained under reflected light using a tungsten lamp source. Photographic filters did not improve the image quality of stained calcium carbonates. Key words: Image analysis, soil micromorphometry

Description: Soil water retention data, predicted from texture, organic carbon content and bulk densities, were compared to measured values. Although significant correlations were obtained, the differences between predicted and measured water contents were large, especially at high potentials, and suggest that extreme caution must be exercised in employing the models under conditions other than those for which they were developed. Key words: Soil water retention, modelling, texture

Description: Potatoes (Solanum tuberosum L.) were grown on a soil with a pH of 4.5 and containing 12 ppm of exchangeable manganese, and in sand cultures where the manganese concentration ranged from 0.2 to 10 ppm. Potassium was supplied in the forms of chloride, sulfate, carbonate, nitrate and hydroxide. On un-limed soils, the yields of tubers were in the following order: K2CO3 〉 KOH 〉 KNO3 〉 K2SO4 〉 KCl. With lime, they were as follows: K2SO4 〉 KCl 〉 KNO3 〉 K2CO3 〉 KOH. The potassium content of potato foliage tended to be lower when lime was added. Liming also reduced the chlorine content of plants by about 20%. Part of the reduction in the potassium and chlorine contents of plants could be the result of greater growth. KCl and K2SO4 increased the uptake of manganese and K2CO3 decreased it. Potassium uptake from the soil where that element was in short supply was in the following order: K2SO4 〉 KCl 〉 KOH 〉 K2CO3 〉 KNO3. In sand cultures where K was plentiful, potassium sources had no effect on potassium uptake by plants. Manganese toxicity builds up very gradually in potatoes. In a period of 9 to 10 weeks, the manganese content of the lower leaves reached a level of 400 ppm (stage where the first symptoms appear), but 5 weeks later they contained 1,200 ppm. Plants containing an excess of chlorine were lighter in color and contained less nitrogen in their leaves but more in their stems.

Description: Although corn (Zea mays L.) stalks contribute to the total quantity of organic material in soil, their direct influence on soil structural stabilization may be small. In a laboratory study 14C-labelled corn stalks were placed on the surface of, or buried at, a 5-cm depth in a sandy loam soil. The soils were incubated at 25 °C for 119 d to determine the extent of organic carbon redistribution. Approximately 70% of the buried stalk carbon and 90% of the surface stalk carbon remained in the soil after incubation. Most of the residual carbon was identifiable as stalk tissue. Less than 5% of the added carbon was intermixed with the soil. Both the lack of C redistribution in the soil and the high loss of the mineralized 14C as CO2 stress the importance of the initial distribution of added organic materials in soils. The results imply that corn stover is a poor source of soil C and that it would be best used as a surface protectant against raindrop impact. Key words: Carbon mineralization, carbon redistribution, corn stalks, soil structure

Description: Wheat (Triticum aestivum L.) was grown in rotation with maize (Zea mays L.) and soybeans (Glycine max L.) as first crops at the National Irrigation Research Station, Nanga, Zambia. Two nodulating soybean cultivars used in the first season of the rotation were compared for their ability to support symbiotic N2 fixation by Bradyrhizobium japonicum using a nonnodulating cultivar as a reference crop and the 15N isotope dilution technique. All first crops received two levels of P (0 or 30 kg P ha−1). The legumes received a blanket application of 20 kg N ha−1, whereas maize received two rates of N (20 and 60 kg N ha−1). There were no benefits of residual P from the first crops to the succeeding wheat. However, the yields of wheat grown on plots where fixing legumes had been grown the previous season were significantly higher than those where maize had preceded. The superior wheat yield in the soybean-wheat rotation over the maize-wheat rotation was attributed to residual N from biological N2 fixation by the preceding legume crop. The benefits were greater when the lower yielding soybean cultivar preceded wheat in the rotation presumably due to its lower soil N demand. Key words: 15N isotope dilution, B. japonicum, N fixation, residual P, residual N, crop rotation

Description: A good statistical relationship was obtained between the exchangeable-sodium ratio and the sodium adsorption ratio (SAR) in Brown Solonetzic and associated soils in southern Alberta. Reliable estimates of the exchangeable-sodium status of these sulfate-rich soils may be anticipated when SAR values are less than 20. Prediction of the exchangeable-sodium status of soils on the basis of SAR values is preferable for both Solonetzic soil and irrigation suitability classification. A saturation extract SAR value of five in the B horizon generally corresponds to an exchangeable calcium to sodium ratio of 10. Saturation extract SAR values of five and 12 are recommended as revised soil chemical criteria for Brown Solonetzic soil and irrigation suitability classification, respectively. Key words: Solonetzic soils, exchangeable cations, sodium adsorption ratio, selectivity coefficient, irrigation suitability

Description: The 0–5 cm depth from Ap horizons of Orthic Brown, Dark Brown and Black Chernozemic soils when recently brought under cultivation, and of unfertilized Dark Brown Chernozemic soils under continuous wheat and a wheat-fallow rotation since 1912 were sampled in early May 1984. The samples were separated into 500- to 1000-μm, 250- to 500-μm, 100- to 250-μm, and

Description: K deficiency was identified for the first time in British Columbia orchard soils. Greenhouse-grown apple seedlings responded to K in soils low in available K. MacSpur McIntosh (Malus domestica Borkh.) had increased leaf K (above deficiency) and improved initial fruiting after surface applications of KCl in an orchard with low soil K. Key words: Potassium deficiency, apple, leaf and soil potassium

Description: Field and growth chamber experiments were conducted to evaluate the short-term effects of selected crops on macro-aggregation of a Kamouraska clay soil. Under field conditions, the growth of barley (Hordeum vulgare L.) and alfalfa (Medicago sativa L.) for up to 2 yr resulted in increased macro-aggregate size and stability compared to a fallow control and to initial conditions. Under these two crops, the proportion of water-stable aggregates of the 2- to 6-mm fraction increased from 25% in May 1986 to 40% in September 1987 at the expense of the 0.25- to 1.0-mm fraction which decreased from 37% to 19% over the same period. Macro-aggregation after 2 yr was not different in corn (Zea mays L.) and fallow control. Seasonal variations in aggregate stability were significant but small and less important than the effects of cropping treatments. Results of the growth chamber experiment agreed with those obtained under field conditions suggesting that controlled environment experiments can be used to model cropping effects on the aggregation of this soil. Key words: Aggregation, soil structure, clay soil, corn, barley, alfalfa

Description: Growth chamber experiments were conducted to investigate the effect of size of fertilizer reaction zone, rate of added zinc and method of placement of added zinc on the dry matter yield, zinc concentration and zinc uptake of blackbeans grown on a calcareous soil. Relationships between zinc concentrations in the plant, zinc utilization by the plant and zinc concentration in the soil reaction zone were obtained. An equation was developed relating zinc utilization to zinc concentration in the fertilizer band, and a figure was derived showing how increasing the size of the fertilizer zone impacts upon the zinc concentration of the plant. The results indicate that inorganic zinc fertilizers must be mixed as uniformly as possible for maximum effectiveness. Key words: Zinc, placement, calcareous, soil, blackbean, Phaseolis vulgaris

Description: The importance of microrelief in relation to mass loss was studied in a Minnesota ombrotrophic forested peatland. Litter and paper strips placed in hummocks for 1 yr lost significantly more mass (two and three times, respectively) than similar material placed in hollows. Less favorable environmental conditions for decomposition, especially lower temperature, reduced decomposition in the hollows. Key words: Peatlands, ombrotrophic, decomposition, Histosols

Description: The objective of this study was to evaluate different available P extracting methods in relation with soil properties, oat yield and plant P uptake. Six chemical extractants (Bray-1, Bray-2, new Mehlich, North Carolina DA-4, DA-10, and Olsen) and two anion exchange resins (F− and HCO3−) were compared on 42 acid soils. The DA-4, DA-10, new Mehlich, and HCO3− resin methods showed the best correlation with oat yield and plant P uptake. The Bray-1, Bray-2 methods were significantly less correlated than the other methods. The HCO3− resin was better than F− resin to predict plant P uptake and yield. Available P levels as determined by these eight methods were classified poor, medium and rich by the Cate and Nelson procedure. Oxalate extractable Al, pH (NaF), pH (H2O), exchangeable (Ca + Mg), forms of P, maximum P fixation capacity and soil texture have great influence on the plant P uptake. Soil organic matter content and oxalate-extractable Fe had significantly less important an effect. The Bray-1 and Bray-2 methods were the most affected by soil properties especially oxalate-extractable Al. The P-HCl/P-DAF ratio proposed by Mehlich to identify forms of soil P indicated that seven soils contain predominantly Ca-P and 21 soils with predominantly Al-P and Fe-P. This ratio was related with oxalate extractable Al (r = − 0.32*), pH NaF (r = − 0.59**), pH H2O (r = 0.52**) and exchangeable Ca + Mg (r = 0.55**). The maximum P fixation capacity (M) ranged from 150 to 4200 μg P/g soil and was closely related with oxalate-extractable Al (r = 0.81**), pH NaF (r = 0.74**), pH H2O (r = − 0.36*) and Mehlich ratio (r = − 0.33*). The maximum P buffering capacity (Mb) of soils was also measured and showed the best correlation with oxalate-extractable Al (r = 0.84**) and pH NaF (r = 0.53**). Key words: Soil testing, available P, anion exchange resins, P fixation, oxalate-Al, forms of P

Description: Studies on thirty mineral soil series and five organic soils from the broad cultivated areas of Quebec indicated that total cobalt, extracted with 70% perchloric acid digestion, ranged from 1.1 to 21.6 ppm and 2.5% acetic acid-extractable cobalt from 0.3 to 0.83 ppm. Extractable cobalt in the surface soils was significantly correlated with total cobalt, which in turn was highly dependent on the clay content of the soil. The soil pH or the organic matter content did not seem to have any influence on the cobalt content in the cultivated soils. Light-textured and podzolized soils are likely to be low m cobalt, while soils with richer clay content are higher. Organic soils, in general, were found to be lower in cobalt content than mineral soils. Nineteen out of the thirty mineral soils studied and all the organic soils contained less than 0.25 ppm of extractable cobalt and may be considered as critical or deficient because forage grown on such soils is likely to cause cobalt deficiency in livestock.

Description: The effect of Ni pretreatments on the yield and concentration of Ni in oats and alfalfa grown in four soils in pot tests varied with the rate of added Ni, with lime and phosphate treatments, and with soil properties, notably pH and organic matter content. The concentrations of Ni in the crops showing repressive effects of added Ni were at least 60 ppm in the oat grain, 28 ppm in the oat straw, and 44 ppm in the alfalfa. The amounts of soil-extractable Ni and the concentrations of Ni in the plants were reduced by liming of the acid soils and they tended to be increased by addition of phosphate. The effects of the Ni pretreatments on growth were less severe in a neutral soil and in one containing considerable organic matter than in the others.

Description: Fe, Al and Mn in distilled warer, NH4-oxaIate, and Na-dithionite solutions were determined by atomic absorption spectroscopy. Concentration ranges for sensitive absorption by Fe, Al, and Mn were 2.5 to 20, 25 to 125 and 2 to 10 ppm, respectively. Concentration ranges of extracting solutions for the determination of Fe, Al and Mn were 0.01 M, 0.20 M and 0.04 M, respectively. Accurate and rapid determinations of Fe, Al, and Mn in NH4-oxalate and Na-dithionite solutions are obtained by atomic absorption spectroscopy without the destruction of the organic extractants.

Description: The influence of birnessite (δ-MnO2) on the precipitation products of iron was studied, in the FeCl2-NH4OH system at different Mn/Fe molar ratios (0, 0.01, 0.1 and 1.0) and in the acidic pH (4.0, 5.0 and 6.0) range, by X-ray, TEM, IR and chemical analyses. The precipitation products formed at pH 5.0 and 6.0 were found to be lepidocrocite (γ-FeOOH) in the absence of birnessite. Birnessite promoted increased precipitation of Fe oxide; the oxidation of Fe(II) by MnO2 was thermodynamically feasible and was confirmed by the presence of Mn(II) in the solution by ESR data. Birnessite also influenced the crystallization processes of hydrolytic products of Fe which range from lepidocrocite through goethite (α-FeOOH), akaganeite (β-FeOOH), to X-ray noncrystalline Fe oxides. The noncrystalline Fe oxides formed at a Mn/Fe molar ratio of 1.0 were characterized by infrared absorption maxima at 1400 and 750 cm−1. Key words: Birnessite, Fe(II) oxidation, ESR, lepidocrocite, akaganeite, noncrystalline oxide

Description: Organic C, N, P, and S contents in soil are thought to be the result of interactions among soil-forming processes, which occur in all soils but to different degrees. To test this hypothesis, the effect of climate, vegetation and topography on the organic matter composition in cultivated soil profiles was examined along an environmental gradient, from semiarid to subhumid regions in Saskatchewan. This transect encompasses a narrow environmental gradient of decreasing evapotranspiration and increasing precipitation (350–450 mm). Representative catenas selected from Brown, Dark Brown, Black and Gray Luvisol soil zones showed changes in the quantity and composition of organic matter. Concentrations of organic C, N, P and S progressively increased from the Brown to the Black soils and then decreased substantially in the Gray soils. Nutrient concentrations also increased from the upper to the lower slope positions of the catenas and decreased with depth in the soil profile. However, the distribution of organic elements across the soil zones, relative to each other (i.e. C:N, C:P, or C:N:P:S ratios), did not follow the same trends as concentration of the individual elements. The most consistent trends were observed in the lower slope soils, where organic C:N (9.8 to 12.5:1), C:P (48 to 78:1) and C:N:P:S (68:6.9:1.4:1 to 145:11.6:1.8:1) ratios widened from the Brown to the Gray soils. Within any one catena, organic C:N:P:S ratios narrowed with depth in the soil profile, often showing a several-fold decrease relative to the C:N:P:S ratios of the surface horizons. This study demonstrates the value of recognizing integrative relationships among soil processes. It provides a mechanism for better understanding and explaining the patterns of distribution and behavior of various soil chemical, physical and biological properties. Key words: Catenary sequence, Chernozem, Luvisol, hierarchical relationships

Description: In an 8-yr experiment on an irrigated Dark Brown Chernozemic soil, four rates of N (0, 34, 67 and 101 kg ha−1), applied annually with 45 t ha−1 of manure containing softwood shavings (avg. of 46% dry wt) produced a linear yield response (from 3.5 with the check to 4.3 t ha−1 at the highest rate) of barley grain (Hordeum vulgare L. 'Galt'). There were large differences in yields among years, which could be attributed to weather factors, but there was no significant N × year response. Protein content increased linearly (from 11.2 to 13.5%), and both kernel weights and "test weights" (kg hL−1) decreased slightly but significantly with N applications. There was a pronounced "residual" effect of N rates on both grain yield (from 3.8 to 6.3 t ha−1) and protein content (from 10 to 13%) in the first year after applications of manure and N fertilizer ceased. These effects decreased rapidly and had practically disappeared by the end of the 3rd yr, although yields of all treatments remained high (about 5 t ha−1). Organic matter and N contents of the soil were increased by 70 and 41%, respectively, from the cumulative applications of shavings manure. It is concluded that application of manure containing large quantities of softwood shavings has a negligible effect on the N fertilizer requirements of the crop being grown. Beneficial residual effects of N fertilizer applied with the manure may result because of buildup of NO3-N throughout the soil profile, and likely also because of N release from readily mineralized organic compounds or microbial biomass. However, this effect was not reflected in soil tests for readily mineralizable N by NO3 incubation or KCl digestion methods and the effects were practically dissipated after 3 yr. The recovery of applied N fertilizer by the crops was high at all rates (61–79%), and essentially all of the N applied (fertilizer + manure) was accounted for by crop removal + increased soil N. Key words: Mineralizable-N soil tests, Chernozemic soil, repeated fertilizer applications, residual effects

Description: In northeastern Saskatchewan on Gray Luvisolic soils, rapeseed (Brassica napus L. and B. campestris L.) grown on many fields does not set seed, possibly because of deficiencies of S and B. Therefore, experiments were begun in 1979 to determine (1) the effect of N, S and B fertilizers on yield and quality of rapeseed; (2) if cultivars (B. napus and B. campestris L.) responded differently to these nutrients; and (3) nutrient and nutrient interaction effects of five rates of N, S and B in a composite rotatable design on yield and quality of the cultivar Regent (B. napus L.). Rates of up to 200 kg N ha−1, 50 kg S ha−1 and 2.8 kg B ha−1 were applied. The experiments were conducted on 13 sites. Nine were in N.E. Saskatchewan on Sylvania f1, Waitville 1 (Luvisolic) and Melfort sicl (Black Chernozemic) soils. Four were in N.W. Saskatchewan on Loon River 1 and Waitville 1, (Luvisolic) soils. In N.W. Saskatchewan there was a significant yield increase because of N (1.00 t ha−1) and S (1.06 t ha−1). In N.E. Saskatchewan on Sylvania f1, rapeseed yields were increased by 0.38 t ha−1 by a combination of S and B and by 0.78 t ha−1 by N. Sylvania f1 soils were lower in soluble B than other experimental sites. At other sites in N.E. Saskatchewan, N but not S increased rapeseed grain yield significantly. Significant response to a combination of S and B was obtained with the cultivar Regent, and both species of rapeseed responded to S fertilizer. Sulphur fertilizer increased the glucosinolate concentration in rapeseed meal at all sites. Sulphur increased oil concentration of rapeseed on all sites except one where frost damaged the crop and increased protein of grain on sites where there was yield response to S. Nitrogen increased protein of rapeseed grown on all sites whereas N combined with B decreased protein and increased oil percentage on all sites except Sylvania f1. The yield response of the cultivar Regent to B was not significantly related to soluble soil B. The combined yield response to S and B in relation to soluble soil S and B was significant (R2 = 0.60). Yield response of rapeseed to S was significantly related to soluble soil S (R2 = 0.35). In conclusion, S fertilizer solved the problem of poor seed set in rapeseed cultivars, but B also enhanced yield by decreasing the number of sterile florets and improving pod development. Key words: Nitrogen, sulphur, boron, rapeseed, oil, protein, glucosinolates

Description: Hydrolysis, immobilization and nitrification of urea-N was measured in samples of Ap horizons of a Black Chernozemic and a Luvisolic soil incubated in the laboratory. Urea was either placed as a nest or mixed throughout the soil. Samples were removed over time to determine the two-dimensional redistribution of urea, [Formula: see text], [Formula: see text], and [Formula: see text]. Localizing urea in a nest reduced both its rate of hydrolysis and subsequent nitrification, and increased recovery of added N in the presence of straw equivalent to 4 t ha−1. In contrast, urea mixed into the soil was nearly completely hydrolyzed and oxidized in 8 d or completely immobilized in the presence of straw. Kinetic studies showed urea hydrolysis was inhibited in a Luvisolic soil sample with increasing substrate concentration beyond 5 mM. The apparent Michaelis-Menten constant (Ka) was 19 mM; the inhibition constant (Ki) was 7 mM; and apparent maximum velocity (Va) was 34.5 μg N g−1 h−1. Urease activity in the Black Chernozemic soil was described by normal Michaelis-Menten kinetics with a Km value of 3.4 mM and Vmax equal to 18.2 μg N g−1 h−1. When urea was localized in a nest, most of the nitrite oxidizers originally present in the soil were killed during the first 24 d of incubation. Factors such as solubilized organics, in addition to [Formula: see text] and [Formula: see text] were considered to be involved. It was concluded that nest placement of urea influenced N transformations in two ways. First, the low surface area:mass ratio reduced exposure of urea to the soil, thereby slowing processes such as immobilization by organisms on decomposing straw. Second, at the microsite level, high concentrations of urea can inhibit urease; and NH3, once generated in such concentrated localized areas, can itself inhibit nitrification through direct toxic effects or possibly through dissolution of inhibitory organics. Key words: Kinetics, Michaelis-Menten, inhibition, nest placement, nitrification, urea

Description: Total sulfur contents of surface horizons of selected Gleysolic profiles were substantially higher (mean of 2,183 and 1,539 ppm for LH and Ah, respectively) than contents previously reported for Chernozemic and Podzolic soils of Alberta. Easily soluble sulfate contents were very variable, with ranges of 20–160 ppm S, 13–1,820 ppm S and 2–1,740 ppm S for LH, Ah and Bg horizons, respectively.Gleysolic profiles contained higher levels of organic sulfur in a reduced state (carbon-bonded sulfur) relative to nitrogen than did better-drained profiles. This trend was less marked with Eluviated Gleysols than with Gleysols or Humic Gleysols.N: total S ratios were extremely variable, with values of horizon samples (LH, Ah and Bg) ranging from 1.3 to 30.

Description: Values of the lime potential, corrected for the varying magnitude of the ionic product (Al) (OH)3, and the degree of base saturation based on the cations extracted with NaCl from acid Ah and Ap horizons of mineral soils and from surface samples of mucks and peats, agreed closely with the curve calculated for the titration of Al bentonite with Ca(OH)2. The peat and muck samples, although strongly acid, had percent base saturation values over 88% owing to the low values of the ionic product (Al) (OH)3 in the aqueous extracts of these organic soils.

Description: Three field experiments were undertaken over a 2-yr period to compare the response of winter wheat to fall-applied large urea granules containing a nitrification inhibitor (dicyandiamide, DCD) with that of commercial urea granules (prills) applied as a top dressing in the spring. The objective was to determine the effectiveness of large urea granules coupled with DCD in conserving N when applied at planting or one month after planting. Granules of 1, 2 and 3 g urea as well as 2 g urea + DCD were compared with commercial urea prills at an application rate of 80 kg N ha−1. Large urea granules, as compared with fall-incorporated commercial urea prills, were effective in conserving N over the winter period especially when applied 1 mo after planting and resulted in yields and apparent N recovery similar to those with top dressed commercial prills applied in the spring. Incorporation of DCD into 2-g granules (50 or 100 g kg−1 urea) further increased the conservation of N fertilizer as reflected by higher yields and greater apparent fertilizer N recovery. Uptake of 15N from 2-g urea granules decreased with distance from the granule. However, plants furthest from spaced large granules were able apparently to obtain sufficient N to reach the yield potential dictated by the weather and soil conditions. Yield and N recovery data indicated that N conservation increased with increasing granule size. Crop response and fertilizer N availability decreased as depth of placement exceeded 10 cm. Placement between the 5 and 10 cm depths appeared to maximize fertilizer N availability. It was concluded that a combination of large urea granules and a nitrification inhibitor (such as DCD) can effectively conserve fall-applied N and result in yield responses and N uptake by winter wheat similar to that with commercial urea prills applied as a top dressing in the spring. Key words: Time of application, yield, 15N recovery, apparent fertilizer N recovery

Description: The effects of application of manure and P fertilizer on wheat yields in a fallow-wheat-wheat rotation on a Black Rego Chernozemic clay soil have been studied for 36 yr. The objective of this study was to identify the effects of manure on soil characteristics that could be related to the reported progressive yield increases over time and an apparent improvement in soil tilth. Soil samples were taken in 1982 from the check (no treatment), and from treatments receiving 13.4, 20.2 and 26.9 t ha−1 of manure applied each fallow year, and 112 kg ha−1 of seed-placed 11-48-0 applied to wheat after summerfallow. Soil physical and P-related parameters were determined for depth increments to 30 cm; the total-N and 15N data to 90 cm; other data were for the 0- to 7.5-cm depth. Manure had no effect on bulk density or hydraulic conductivity. However, it increased the total C and humic acid (HA) content of the soil, the percent of soil C as HA-C, the C concentration in humin, and the percent of total soil N as humin-N. Manure significantly increased the percent of HA-N but not humin-N present as amino acid and amino sugar-N, but increased amino acids and the amino sugars in the humin hydrolysate. The net rate of N mineralization and the available forms of inorganic P were all increased significantly by manure. The natural 15N-abundance technique showed that a significant though small proportion of soil N was derived from manure. Manure had no effect on soil microbial biomass C and N, soil respiration, and the quantity of potentially mineralizable N. Applied P had no effect on N-related parameters measured; its effect on available P was not measured. It was concluded that manure increased crop yields by improving the N- and P-supplying power of the soil, and improving the physical environment of the soil through its effects on the humic colloids. Key words: Humic substances, soil P fractions, soil biological properties, natural 15N abundance, net N mineralization

Description: The objective of this study was to evaluate the Kelowna multiple element extractant and some EDTA and DTPA modifications for simultaneous determination of potassium and sodium in acid and calcareous soils. To that end, the relationships between K and Na concentrations extracted with 1 N NH4OAc and the Kelowna multiple element extractant (0.25 N HOAc + 0.015 N NH4F) were assessed. However, relationships between K and Na concentrations removed by the modified Kelowna multiple element extractants containing either EDTA or DTPA (KEDTA & KDTPA with NH4F; and AAEDTA & AADTPA without NH4F) were evaluated by comparing values against those obtained with the Kelowna extractant. Addition of these complexing agents was of interest because of their potential in enabling simultaneous extraction of available Zn. The procedures were evaluated by contrasting K and Na concentrations extracted from 100 Canadian soils — half which had pH values between 4.1 and 6.9 (H2O) and a second group with values between 7 and 9.6 — by means of graphing, regression and correlation techniques. Potassium and sodium concentrations removed by the Kelowna extractant ranged from 25 to 510 μg and from 10 to 1420 μg mL−1 soil, respectively. The Kelowna and its EDTA and DTPA modifications extracted K and Na as effectively from acid as calcareous soils. This conclusion was supported by the similar regression slopes obtained when relating concentrations of K and Na removed from these soil groups by the multiple element extractants against those removed by 1 N NH4OAc (r-values ≥ 0.97**). However, the new multiple element extractants removed an average of about 20% less K than 1 N NH4OAc from these soils, though similar Na levels. The lower K levels removed from the Kelowna extractant, or by one of its modifications, may require that soil test interpretation norms be adjusted to compensate for the lower values when using one of these to determine K-availability. A significant correlation was found between extracted Na levels and 1:2 vol/vol water-extract conductivities (r ≥ 0.83**) suggesting that "higher" Na levels may be soluble instead of exchangeable. Some Na test interpretations are discussed in the text. Key words: EDTA, DTPA

Description: Nitrogen in fallow soil in four field trials was monitored at Agassiz to examine the response of N processes under humid weather conditions of south coastal British Columbia. Inorganic N in the soil profile of control and ammonium-nitrate-treated plots were compared at various time intervals. In two trials (Spring-78 and Spring-81) treatments were applied in late May and in two (Fall-79 and Fall-82) in early November. Leaching of spring-applied N was quite limited during the spring and summer. In the Spring-78 trial, there was negligible nitrate movement until September whereas in the Spring-81 trial there was some movement in June. In the Spring-81 trial, upward movement of nitrate was detected in late August. Nitrate leaching in the summer of 1981 was associated with an unusually high amount of precipitation during June. Leaching of nitrate was significant in late October to December. Nitrogen applied in early November showed extensive leaching by late December. The ammonium appeared to have been nitrified quickly to enable leaching of the applied N as nitrate. Leaching of nitrate appeared to be associated with net water surpluses (precipitation less pan evaporation). Clay fixation of applied ammonium was detected immediately after fertilizer application in the fall but not in the spring trials. The applied ammonium that was fixed by clay was apparently released during the monitoring period. An increase of surface acidity due to ammonium nitrate application was detected in the Fall-79 trial. Comparison of nitrate leaching with long-term precipitation and pan-evaporation records shows that there is low risk of nitrate leaching during the spring and summer but high risk during the fall and winter in south coastal British Columbia. It was concluded that residual inorganic N after the growing season would not be available for crop growth in the spring due to nitrification and leaching over the winter. Development of a soil test for N would have to concentrate on the potential of the soil to mineralize soil N in the spring and early summer. Key words: Nitrogen leaching, nitrogen transformations, clay fixed NH4+, nitrification, fall nitrogen application

Description: The extent of movement of phosphorus from the application site of P-32 labelled monoammonium phosphate and diammonium phosphate pellets was investigated. The rate of movement of phosphorus from a monoammonium phosphate pellet was also studied. The extent of phosphorus movement from a monoamnionium phosphate pellet was greater than that from a diammonium phosphate pellet. This observation was more noticeable in the calcareous soils than in the noncalcareous soils. The extent of phosphorus movement was greater in noncalcareous soils than in calcareous soils for both sources of phosphorus when added as a pellet. The rate of movement of phosphorus was also more rapid in noncalcareous soils than in calcareous soils.It is most likely that the high pH and large amounts of calcium and magnesium found in the soil solutions of the calcareous soils resulted in a rapid precipitation of the added phosphorus very close to the pellet site. Thus, the rate and extent of phosphorus movement in the calcareous soils was restricted more than in the noncalcareous soils, which had a lower pH and contained smaller amounts of calcium and magnesium in the soil solution.

Description: Effects of tillage on soil morphology and porosity were investigated in plots planted to corn (Zea mays L.) for seven consecutive years. Micromorphometric analyses indicated that Ap horizons of no-till plots had approximately half the macroporosity (pores ≥ 200 μm equivalent circular diameter) of those of conventionally tilled plots. Loss of macroporosity was characterized by a decrease in mean pore size and a tendency for pores to become elongated, less tortuous, and oriented parallel to the soil surface. Obvious zoological activity, which consisted mainly of burrowing earthworms, resulted in two to nine times more bioporosity in a no-till pedon than in a conventionally tilled pedon. Earthworm activity also contributed to the formation of 5-cm-thick B & A horizon and a more uniform distribution of organic carbon than in the conventionally tilled pedon. These differences in morphology are reflected in the classification under Soil Taxonomy but not under the Canadian System. We speculate that zoological activity may serve to counteract the reduction in macroporosity in the Ap of the no-till pedon. Key words: Bioporosity, earthworms, micromorphometric analysis, zoological activity

Description: Properties of three clay soils of differing wetness were related to water table levels and redox conditions. High Eh values and low water table prevailed throughout 2 years at the Wendover site. The soil, an Orthic Acid Brown Forest, was weakly developed with a thin Ah horizon and a Bm horizon in which vermiculite apparently formed from mica. At the level Bearbrook site, the water table fluctuated between the surface and 8 ft, the solum varied in moisture from saturation to extreme dryness, and Eh values fluctuated between 800 mv and −150 mv. A thin but distinct Aeg horizon of low base saturation underlay the H horizon. A marked accumulation of free iron oxide occurred in the strongly mottled Bfg horizon. Clay mineralogy changed from largely vermiculite in the Aeg horizon to montmorillonite and illite in the underlying horizons of this Orthic Gleysol. The water table was usually within 2 ft of the surface at the Laplaine site. This Peaty Rego Gleysol had an H horizon underlaid by olive-gray clay in which properties changed little with depth. Horizon differentiation appeared to be favored by wide seasonal fluctuations in moisture status and redox potentials.

Description: The effects of crop rotation and fertilization on moisture conserved and moisture use efficiency (MUE) were assessed on a loam soil in the Brown soil zone of southwestern Saskatchewan over the period 1967–1984. Six spring wheat rotations were examined that were either fertilized at soil test recommended rates of N and P, or N or P was withheld according to rotation specifications. MUE in this study was calculated as grain yield divided by sum of 1 May to 31 Aug. precipitation plus soil moisture used between seeding and harvest. In the first fall after harvest 8–11 % of the precipitation received was stored in soil in all rotations. During the first winter 3–5 times as much moisture was stored as was stored in the fall; compared to continuous wheat receiving only P, continuous wheat fertilized with N and P increased moisture storage by 12 mm due to a larger amount of crop residues left in the field. In the first 9 mo of summer-fallow, 33% of the precipitation was stored, but over the entire 21-mo fallow period only 18% was stored. At seeding, fallow-seeded crops receiving P annually had 43 mm more moisture in the 120-cm profile than stubble-seeded wheat that received N and P. Failure to apply P to wheat grown on fallow in the F-W-W rotations reduced spring soil moisture at seeding by about 8 mm. Wheat seeded on fallow retained more moisture in soil compared to wheat seeded on stubble until the shot blade stage, but at harvest and fall sampling there was no difference. At harvest there was no available moisture in the top 90 cm of soil. Wheat made greater use of stored soil moisture in dry years than in wet. Wheat grown on fallow that received P used 102 mm of soil moisture per year; wheat on fallow receiving no P used 93 mm; wheat on stubble receiving N and P used 61 mm and continuous wheat receiving no N used 50 mm. The 18-yr average MUE was as high as 6.9 kg ha−1 mm−1 for wheat on fallow that received P and as low as 5.1 kg ha−1 mm−1 for continuous wheat receiving no N. These values were much greater than those reported 30–40 yr ago for this area and reflect improved crop management and crop varieties now used. The improvement in MUE due to fertilizer was greater in later years due to the cumulative effect of fertilizer on soil quality, crop production and crop residues which enhanced moisture available for use. When efficiency was based on the precipitation received from harvest to harvest continuous wheat receiving N and P had the highest efficiency (3.75 kg ha−1 mm−1) and the 2-yr fallow-wheat rotation the lowest (2.60 kg ha−1 mm−1). Key words: Water use efficiency, WUE, nitrogen, phosphorus and moisture use, summerfallow and moisture conservation

Description: The effect of replacing NO3− with SO42− in solution on exchange between Al3+ or Fe3+ and Ca2+ was investigated for aqueous acid clay systems. It was found that if the activities of the cations in solutions were not corrected for soluble cation–SO42− complexes the results with SO42− were definitely different from those with NO3−. When the corrections for complexing were made there was little if any difference between the results with the two anions, as far as exchange reactions and the relation between adjusted lime potential and degree of Ca2+ saturation of clays were concerned. The presence of SO42−, however, had a marked effect on the ion product (Fe) (OH)3 but not on (Al)(OH)3 in solution.

Description: In sequences of grassland soils on south-facing slopes and forested soils on north-facing slopes in southern British Columbia, pH decreased but C, N, and organic phosphorus (Po) increased with increase in elevation from 1800 to 7400 ft. At the highest elevations grassland and forested soils contained similar amounts of C, N, and Po. The surface horizons of grassland soils at the lowest elevations contained C and N in similar amount to forested soils between 4000 and 5000 ft. C, N, and Po decreased with depth in all profiles but the amount of H2SO4-soluble inorganic P (Pa) increased to its highest percentage of the total, up to 98%, in the parent materials. Although both C/N and C/Po ratios decreased with depth, the values for C/Po were not high and indicated that inorganic phosphorus supply is not limiting the accumulation of P in the soil organic matter. These properties were interpreted as the effects of climate, modified by elevation, aspect, and vegetation, on weakly weathered parent materials.

Description: Yields of wheat and to a lesser extent flax were greater following June breaking of virgin bushland than following September breaking. Shallow moldboard breaking was superior to deep breaking for the production of wheat but deep breaking generally gave the higher yield of flax. Land broken with a moldboard plough produced a higher yield of flax than land broken with a serrated disc plough but moldboard breaking had less advantage for the production of wheat.Yield differences among the breaking methods were sharply reduced in the second cropping year for both wheat and flax, and wheat yield differences disappeared by the fifth crop. Yield differences among the breaking methods were also markedly reduced by summerfallowing before cropping to wheat. Regrowth of native willow (Salix sp.) and poplar (Papulus sp.) were also affected by the breaking methods but a definite relationship between amount of regrowth and crop yields could not be shown.

Description: In greenhouse experiments involving the placement of Sr90 and fertilizer in the soil, marked reductions in Sr90 concentration were found for timothy and wheat when the Sr90 was placed deep in the soil compared with the results found for shallow placement. Fertilization of the soil above the zone of Sr90 contamination led to further decreases in Sr90 concentration in timothy and wheat.Results for alfalfa differed from the results for timothy and wheat. A combination of shallow fertilization and shallow placement of Sr90 caused the highest concentration of Sr90 in plants. Deep placement of Sr90 did not reduce the Sr90 concentration in the first cutting of alfalfa, but as the plant matured, there was a reduction caused by deep placement of Sr90. Deep placement of Sr90 combined with deep placement of fertilizer caused an increase in the Sr90 concentrations in alfalfa compared with deep placement of Sr90 alone. The greatest reductions in Sr90 in the plants were found where the deep placement of Sr90 was combined with shallow placement of the fertilizer. Surface or subsurface watering of the crop did not affect the main conclusions with regard to placement of Sr90 and fertilizer.

Description: Numerous techniques for measuring near-surface soil moisture with a neutron probe have been reported. Placing the neutron probe horizontally on the ground surface within a hydrogenous shield has been discussed theoretically, but field adaptations have not. Such a shield was designed and used, yielding measurements of near-surface soil moisture quickly and accurately. Key words: Neutron probe, soil surface moisture, calibration

Description: Nosema locustae Canning is a potential biological control agent for grasshoppers but some aspects of its environmental impact have not been investigated. This study assessed the impact of N. locustae and the chemical insecticides carbofuran, deltamethrin and dimethoate on microbial activity and nutrient cycling in soil. In a laboratory study, the insecticides were applied to a Haverhill loam at recommended field application rates and 10 times the field rates. There was no adverse effect from N. locustae or the chemical insecticides on any of the measured parameters. Analysis of field soils 6 wk after application of a mixture of N. locustae and dimethoate indicated this treatment had no adverse impact on microbial activity. Key words: Nosema locustae, carbofuran, deltamethrin, dimethoate, microbial activity

Description: The relationships among the spatial variations of soil water content, soil texture, soil solution electrical conductivity, and bulk soil electrical conductivity were examined for a field characterized by net drainage and low concentrations of dissolved electrolytes. Bulk soil electrical conductivity was measured over various depths at 52 locations within a 1.8-ha field using noncontacting electromagnetic inductive meters. Soil water content (0–0.5 m depth) was measured at the same locations using the time domain reflectometry method. Measurements of soil texture and soil solution conductivity were obtained from core samples from 37 of the sampling locations. Soil water content at the site ranged from 0.06 to 0.36 m3 m−3. Clay content ranged from 2.5 to 44% percent and bulk soil electrical conductivity ranged from 0.0 to 0.21 S m−1. Significant correlation existed among almost all of the measured variables. Regression analysis indicated soil solution conductivity had no effect on measured bulk soil electrical conductivity for soil water contents less than 0.25 m3 m−3. Bulk soil electrical conductivity explained 96% of the spatial variation of soil water content independent of a wide range of soil texture. Autocorrelations of soil water content were similar to autocorrelations for bulk soil electrical conductivity. Under conditions similar to those in the study area, it should be possible to infer spatial variations in soil water content quickly by measuring bulk electrical conductivity using noncontacting electromagnetic inductive meters. Key words: Spatial variability, soil water, electrical conductivity, soil texture

Description: Amounts and turnover rates of biomass and water-soluble organic C (WSOC) were measured at the Breton plots where records of long-term management of a Gray Luvisolic soil are available. Plots (control, manure, and NPKS) which had been cropped to either a wheat-fallow or a wheat-oats-barley-forage-forage rotation for 50 yr were sampled 13 times during 1981 and 1982. Biomass C and flush of microbial N were measured using the chloroform fumigation technique. Long-term crop yields were used to derive C supply to the plots. Regression analyses were used to relate seasonal fluctuations in environmental conditions to biomass and WSOC dynamics. Reinoculation with soil was unnecessary but Lysobacter sp. formed a greater proportion of isolates following incubation of fumigated soil than of unfumigated samples. Reinoculation with Lysobacter sp. is suggested to provide a more standardized biological assay. The 5-yr rotation contained 38% more N but 117% more microbial N than did the 2-yr rotation, and manured treatments contained twice as much microbial N as did NPKS or control plots. A management effect on soil organic matter quality is indicated. Averge turnover rates of biomass were 0.2–3.9 yr−1; being 1.5–2 times faster in the 2-yr rotation than in the 5-yr rotation. Replenishment of the WSOC component would have to occur 26–39 times yr−1 to supply microbial turnover. Most of the biomass must be dormant because annual C inputs are two orders of magnitude less than maintenance energy requirements. Seasonal variations in biomass were most consistently related to losses during desiccation and regrowth upon moistening. Regrowth appears to be at the expense of native soil organic matter. Management practices and environmental conditions therefore affect amount of organic matter by controlling both input of C and biomass turnover. Key words: Crop rotations, Luvisol, organic matter, biomass, soluble C, Breton plots

Description: Mean annual rates of calcium carbonate removal from soils in a subarctic climate estimated from data on two chronosequences of calcareous storm ridges, appeared to be relatively constant through time. Concentrations of dissolved calcium carbonate in the soil solution in the study sites calculated from the rates of weathering of CaCO3 and of water drainage are in the range expected for equilibrium with calcite. The same conclusion could be drawn from published studies elsewhere. Over a wide range of conditions, the dissolution rate of calcite appears to be high enough to maintain equilibrium concentrations in water percolating calcareous soils and rocks. Consequently, the rate of calcium carbonate weathering can be predicted from (1) the solubility of CaCO3 and (2) the water drainage rate. Key words: Calcium carbonate weathering, soil chronosequence, subarctic soils

Description: A soil chronosequence near Cox Bay, on the west coast of Vancouver Island, British Columbia was investigated. Soils in the sequence have developed on sandy beach deposits, which are advancing toward the ocean at a rate of 0.26 m per year. Dendrochronology and geomorphology established surface ages ranging from 127 to 550 yr for seven selected pedons across these deposits. With soil age, there was progressive deepening and differentiation of genetic horizons, resulting in soil classification that ranged from an Orthic Dystric Brunisol at the youngest site (site 1) to an Orthic Humo Ferric Podzol at the oldest site (site 7). Organic matter increased from a maximum value for mineral horizons of 1.1% in the Bm of site 1 to 4.7% in the Ae of site 7. Oxalate-extractable Al in the uppermost B horizons of the soils increased from 0.12% at site 1 to 0.30% at site 6. Available Mg and K from the lowermost horizons sampled decreased from 35 and 25 mg kg−1 to 4 and 5 mg kg−1, respectively, when moving from sites 1 to 6. Accumulations of organic matter, Fe and Al, and losses of available Mg were plotted against soil age and yielded chronofunctions with exponential solutions. Key words: Soil chronosequence, soil genesis, Podzol development, chronofunctions

Description: Successful reduced tillage systems depend on suitable soil types and the maintenance of optimum soil structure. Studies were conducted to assess the tillage requirement of some well-drained Podzolic and Luvisolic soils in Prince Edward Island and their suitability for direct drilling. Relatively high amounts of silt and fine sand indicated that the soils were structurally unstable with a propensity for compaction. Compactability was inversely related (r2 = 0.90) to concentrations of soil organic carbon over a range of 0.2–2.0%. In the Ap horizons, where organic carbon exceeded 1.6%, the level of macroporosity (equivalent pore diam. 〉 50 μm) was generally greater than 10%. The B horizon and lower level of the Ap horizon, generally, had low porosity and organic matter, although pore continuity was adequate. Macroporosity was closely related to soil bulk density (r2 = 0.81). Penetrometer resistance down the soil profile indicated a relatively shallow rooting depth potential of 25–40 cm. A 3-yr direct drilling study with spring cereals illustrated that some degree of soil loosening is required to maintain optimum soil structure. Soil limitations for direct drilling were mainly low resistance to compaction combined with low potential for regeneration of soil structure. The possible implications of the soil physical properties are discussed in relation to the use of direct drilling within the short-term rotational mixed farming systems of Prince Edward Island. Key words: Soil structure, macropores, Podzolic soils, Luvisolic soils

Description: Experiments were made to investigate the effect of experimental conditions on the forms of Al adsorbed from solution by clays. It was found that when Ca(OH)2 was added to suspensions of clay in approximately 10−2 M solutions of AlCl3, the titration curves of the 2 N NaCl extracts of the clays showed one buffer zone between pH 4 and 5. If the Ca(OH)2 was mixed with the AlCl3 solution before adding the clay, the titration curves of the NaCl extracts showed, besides the normal buffer zone between pH 4 and 5, a second one near pH 6. Since the Al material that titrated near pH 6 was formed in the mixtures of Ca(OH)2 and AlCl3, removed from the dilute salt solutions by clay and released again to 2 N NaCl, it was assumed to be positively charged, exchangeable, polymeric Al ions. These polymeric ions were depolymerized and measured as monomers by the aluminon method. Heating the clay-AlCl3 suspensions, to which Ca(OH)2 had been added, to 100 °C also produced these exchangeable, polymeric Al ions but in this case they were not depolymerized and measured by the aluminon method.

Description: Several methods for providing an index of the availability of soil nitrogen were evaluated by relating laboratory soil test values to yields of dry matter and uptake or nitrogen by orchardgrass in the greenhouse. Determination of soil organic matter or total soil nitrogen contents was relatively ineffective. Available nitrogen initially present in the soil at sampling time, extracted by several different methods, was superior to measurements of nitrogen released upon incubation. The nitrate form of nitrogen, either initially present or released upon incubation, served as a better index of soil nitrogen availability than the ammonium form. Inclusion of initial nitrates and nitrates released upon incubation as independent variables in a multiple regression resulted in the highest correlation with total nitrogen uptake. In the three incubation methods evaluated, discarding the initial nitrogen content of the soil, as is commonly done, severely reduced the validity of the tests as measures of nitrogen availability.

Description: Additions of Ca(OH)2 and/or organic matter to an unproductive soil with a high content of extractable Ni and a low Ca:Mg ratio (

Description: not available

Description: Sodium bicarbonate extractable organic phosphorus increased with increasing pH of extractant, temperature, time of extraction, and soil/solution ratio. The inclusion of an acid pretreatment resulted in higher organic phosphorus levels than bicarbonate extraction only.The proposed method involves extraction with 0.5 M sodium bicarbonate at pH 10.0 for 16 hours at 90 °C following acid pretreatment with 0.5 N hydrochloric acid for 1 hour. Under these conditions 98.8% of the total organic phosphorus, as estimated by the method of Mehta et al., was extracted.

Description: Properties characterizing the hydraulic behavior of three soils were determined from drainage cycle tests using samples wetted with core test fluid by three saturation techniques: saturation under vacuum, saturation from below at atmospheric pressure and saturation from above at atmospheric pressure. Saturated permeability and pore-size distribution index were notably less for samples saturated at atmospheric pressure than for the vacuum-saturated samples. Bubbling pressure and residual saturation, on the other hand, were not affected by saturation technique. The observed dependence of saturated permeability and pore-size distribution index on saturation technique was attributed to the effect of entrapped air. In the modeling of field problems, determining the hydraulic properties of soils wetted at atmospheric pressure is advised.

Description: A micropenetrometer with a diameter similar in magnitude to that of a root is capable of measuring variations in tip resistance over distances as small as 0.1 mm. Measurements at this scale offer the potential of characterizing zones of high resistance to penetration and the frequency of occurrence of zones of low resistance which could be exploited by a growing root. Spectral analysis provides a new approach to characterizing soil structure and has been applied to the micropenetrometer tip resistance profiles obtained from beds of aggregates. Nine different aggregate size ranges were considered; the aggregate diameters varied from less than 0.36 mm to 6.4–12.8 mm. The analyses indicate that larger aggregates are more resistant to penetration. In addition, comparison of variance spectra among several of the aggregate sizes reveals information on the structural make up of soil aggregates, namely that larger aggregates are made up of smaller "component" aggregates which offer higher resistance when they occur in large aggregates than when they occur individually in loose packing. The use of spectral analysis also appears to provide information on the spatial separation of zones of low resistance which correlate with aggregate size if the aggregate diameters are larger than 1.6 mm. Key words: Soil strength, soil resistance to penetration, micropenetrometer, aggregate size

Description: not available

Description: The effects of wheat straw incorporation on denitrification, immobilization of N, and C mineralization were investigated at H2O contents of 60, 90 and 120% saturation. Incorporation of increasing levels of straw consistently increased the rate of denitrification for the first 4–8 d, followed by negligible N losses thereafter. In a total period of 96 d, the addition of 1.0% straw increased N losses from 2.5 to 10.1, and from 61.6 to 83.9 μg g−1 in the 60 and 120% water saturation treatments, respectively. The pattern of CO2-C evolved was practically identical to that of the denitrification rate for the initial period when sufficient [Formula: see text] was present. This study has confirmed that in flooded soils, high rates of denitrification will persist only when C is supplied by native or applied organic C sources, provided adequate [Formula: see text] is present. When [Formula: see text] was low, denitrification rates rapidly decreased, even with a sufficient supply of C. Immobilization of fertilizer N (50 μg N g−1 as K15NO3) was very rapid. Around 90% of the total immobilization of applied N occurred within 4 d. Incorporation of 1.0% straw increased the immobilization of fertilizer N from 8.4 to 42.8, and from 1.0 to 7.6% in the 60 and 120% water-saturated treatments, respectively. Remineralization of recently immobilized fertilizer N was observed after 32 d in the 60% saturation treatments only. Key words: Denitrification, wheat straw, mineralization of N

Description: Fields tests were conducted with commercial fertilizers applied to barley, flax and rapeseed by placement in the row and by placement in different positions away from the row. Emergence of barley was delayed but not substantially reduced by row placement of 33.5–0–0 at a rate of 34 kg N per ha, or by 0–45–0 and 11–48–0 at rates up to 39 kg P per ha. Yields were no greater when the fertilizers were, instead, placed away from the row.Emergence of flax and rapeseed was often reduced to less than half by row placement of 33.5–0–0 at a rate of 17 kg N per ha, or by 11–48–0 at rates of 15 to 20 kg P per ha, and yields were usually greater when damage to emergence was avoided by placing the fertilizers away from the row. When higher rates of fertilizers were used, placement away from the row produced much greater yields than placement in the row.The efficiency of the phosphorus fertilizers varied considerably with the position in which they were placed. When phosphorus fertilizers were placed away from the row, a position 2.5 cm directly below the row was the best for both barley and flax.

Description: An evaluation of polyethylene glycol (P.E.G.) 6000 and P.E.G. 20,000 in the osmotic control of soil water matric potential was conducted using the pressure membrane as a standard. Results indicated that there were no statistically significant differences between the three methods at four matric potentials between −0.51 and −15.3 atmospheres. Hence, either P.E.G. 6000 or P.E.G. 20,000 can be used satisfactorily in the osmotic control of soil water matric potential.

Description: not available