bluuebunny/crossref_metadata_2025 huggingface dataset:
SOIL SALINITY AND SAND CONTENT VARIABILITY DETERMINED BY TWO STATISTICAL METHODS IN AN IRRIGATED SALINE SOIL
Authors: Chang C. , SOMMERFELDT T. G. , ENTZ T.
Published: March 2010

Knowledge of the variability of soluble salt content in saline soils can assist in designing experiments or developing management practices to manage and reclaim salt-affected soils. Geostatistical theory enables the use of spatial dependence of soil properties to obtain information about locations in the field that are not actually measured, but classical statistical methods do not consider spatial correlation and the relative location of samples. A study was carried out using both classical statistics and geostatistical methods to delineate salinity and sand content and their variability in a small area of irrigated saline soil. Soil samples were taken for electrical conductivity (EC) and particle size distribution determinations at 64 locations from a 20 × 25-m area, on an 8 × 8-grid pattern at depth intervals of 0–15, 15–30, 30–60, 60–90 and 90–120 cm. The high coefficient of variation (CV) values of both EC and sand content indicated that the soil was highly variable with respect to these soil properties. The semivariograms of sand content of the first two depth intervals and EC of all the depth intervals showed strong spatial relationships. Contour maps, generated by block kriging, based on spatial relationships provide estimated variances which are smaller than general variances calculated by the classical statistical method. The interpolated EC results by both ordinary and universal kriging methods were compared and were almost identical. The kriged maps can provide information useful for designing experiments and for determining soil sampling strategy. Key words: Salinity, texture, variability, geostatistics, semivariogram, kriging
ORTHO- AND POLYPHOSPHATE P FERTILIZERS AS AFFECTED BY ADDED ORGANIC MATERIALS AND CALCIUM CARBONATE
Authors: MNKENI P. N. S. , MACKENZIE A. F.
Published: March 2010

Studies were conducted in the growth chamber to compare sodium orthophosphate (NaOP), sodium pyrophosphate (NaPP) and PolyN (a triammonium pyrophosphate-orthophosphate mixture) as sources of P for barley in four Quebec soils treated with farmyard manure (FYM) or alfalfa residues. The effect of calcium carbonate was also studied in two acidic soil samples. Added P at 440 kg ha−1 increased barley yields and P uptake on three soil samples. Lack of growth responses at lower rates on a subsoil sample were attributed to soil acidity or micronutrient deficiencies. In nonamended soils, NaOP and NaPP were equally effective as sources of P for barley but PolyN was less effective. In soil samples treated with alfalfa residues, PolyN was as effective as other carriers. These results were attributed to the effects of alfalfa residues in reducing ortho- and polyphosphate sorption. Amendment with FYM masked carrier effects on yield because of the presence of added P in the manure. Soil acidity effects and possible micronutrient deficiencies were ameliorated with added FYM. In CaCO3 amended Uplands topsoil, NaOP was superior to NaPP or PolyN. Key words: Farmyard manure, alfalfa residues, barley, Hordeum vulgare L., pyrophosphate, calcium carbonate
PERFORMANCE OF THREE REGRESSION-BASED MODELS FOR ESTIMATING MONTHLY SOIL TEMPERATURES IN THE ATLANTIC REGION
Authors: DWYER L. M. , BOOTSMA A. , HAYHOE H. N.
Published: March 2010

The purpose of this study was to compare the performance of three regression-based macroclimatic models for estimating monthly soil temperatures under short grass cover at five depths (0.10, 0.20, 0.50, 1.00 and 1.50 m) in the Atlantic region of Canada. The models tested were: (1) an existing national-scale model (model 1) which estimates monthly soil temperatures from climatic predictor variables related to air temperature, rainfall, snowfall and potential evapotranspiration and which was derived using data from selected stations all across Canada; (2) a new model (model 2) using similar predictor variables as model 1 but which was developed using data from five locations in the Atlantic region only; (3) a new model (model 3) derived using data from the same locations and periods as model 2 but which included new predictor variables related to snow depth. Improved soil temperature models are required since estimates from existing regression models based on national data can have significant biases when applied to regions or specific locations. Tests based on dependent data up to 1981 (used to develop models 2 and 3) showed that mean correlation coefficients between observed and estimated soil temperatures were 0.61, 0.71 and 0.77, respectively, for models 1, 2 and 3. Correlation coefficients averaged for the months of January through March were 0.32, 0.60 and 0.80, respectively, indicating that greatest improvements were achieved for winter months by including predictor variables related to snow depth. Model 3 also had considerably lower standard errors than model 2 during winter months. Tests using independent data from 1982 and 1983 indicated a general improvement in estimates from models 2 and 3, although results were less conclusive due to abnormal snow cover conditions in both years and the relatively short test period. Key words: Regression model, monthly temperatures, stepwise regression, variable selection
REGRESSIONS FOR ESTIMATING STRAW YIELDS AND N AND P CONTENTS OF SPRING WHEAT AND N MINERALIZATION IN A BROWN LOAM SOIL
Authors: CAMPBELL C. A. , ZENTNER R. P. , SELLES F.
Published: March 2010

Data from an 18-yr crop rotation study carried out on a Brown loam soil at Swift Current, Saskatchewan, were used to estimate equations that relate spring wheat straw yields, and N and P content of grain and straw to moisture use (MU). Moisture use was defined as soil moisture content in 0- to 120-cm depth at seeding, less soil moisture content at harvest, plus growing season precipitation. Grain yields were also related to straw yields and to N content of the straw. Potential net N mineralization (Nmin) in summerfallow (periods during the growing season with negative Nmin omitted) was related (r = 0.74**) to precipitation received during the spring to fall period. An attempt to relate apparent net Nmin (determined by N balance) in cropped systems to growing season precipitation or to MU was not successful. Highly significant linear regressions were obtained for straw yields, grain N and P contents vs. MU, and for grain yield vs. straw yield (r = 0.66** – 0.83**), but the other relationships were less reliable (r = 0.41** – 0.55**) though still significant. We discussed how these relationships might be used to estimate fertilizer N requirements, for examining N immobilization-mineralization, and for estimating residue sufficiency for erosion control on summerfallowed land. Key words: Straw:grain ratio, N uptake, P uptake, crop residues, N mineralization
THE MECHANISM OF PHOSPHORUS-INDUCED ZINC DEFICIENCY IN BEAN (Phaseolus vulgaris L.)
Authors: SINGH J. P. , KARAMANOS R. E. , STEWART J. W. B.
Published: March 2010

The nature of the P-induced Zn deficiency in bean plants was studied in a growth chamber experiment using three pedogenically different soils. Application of P (0, 40, 80 and 160 mg P kg−1 soil) resulted in significant dry matter (DM) yield increases. Maximum DM yields were attained at the 40 mg P kg−1 application rate. Application of Zn (0, 5 or 10 mg Zn kg−1 soil) without P application had no effect on DM yields of bean plants. However, Zn application in combination with P application resulted in significant DM yield responses. There was no evidence that the P-induced Zn deficiency was a result of differences in soil characteristics or influence of P on the water soluble plus exchangeable, organically bound, Mn- and Fe-oxide bound or residual Zn fractions. The Zn concentration in bean plant tops was significantly reduced due to P application and the magnitude of the reduction was greatest with the first increment of applied P (40 mg P kg−1 soil). Application of P induced Zn deficiency, at least partly, by stimulation of growth and subsequent dilution of tissue Zn concentration. Translocation of Zn from roots to tops appeared to be restricted at 80 and 160 mg applied P kg−1 soil treatments, as evidenced by the reduction of Zn uptake in non-Zn treatments. Thus, plant dilution effects and reduced translocation of Zn from roots to tops were the two mechanisms responsible for the observed P-induced Zn deficiency in this study. Key words: P × Zn interaction, plant availability, plant uptake, soil Zn fractions, soil P, Zinc-65
SEASONAL VARIATION OF ERODIBILITY INDICES BASED ON SHEAR STRENGTH AND AGGREGATE STABILITY IN SOME ONTARIO SOILS
Authors: COOTE D. R. , MALCOLM-McGOVERN C. A. , WALL G. J. , DICKINSON W. T. , RUDRA R. P.
Published: March 2010

Soil-erodibility indices were investigated in two regions of Ontario to evaluate their seasonal variation and differences between soil types. Shear strength and water-stable aggregates >0.5 mm were strongly negatively correlated with gravimetric soil water content for a Guelph sandy loam soil in southwestern Ontario. Similar variation of shear strength was estimated in three other southwestern Ontario surface soils as a result of seasonal changes in moisture content. Shear strength and aggregate stability increased as four eastern Ontario soils, ranging in texture from loamy sand to clay, dried and warmed following spring thaw. Laboratory incubation at constant temperature and water content showed that shear strength increased in two fine-textured soils with increasing degree days but changed very little in two coarse-textured soils. At the point-of-thaw in the field, all of the eastern Ontario soils exhibited very high values of the indices 1/shear strength and 1/aggregate stability, averaging approximately 15 times those of early July. During spring fallow and seed-bed to 10% canopy periods, the mean values of these indices were 3.7 and 1.4 times, respectively, those in early July. For winter-thaw conditions in the three southwestern Ontario soils, the index 1/shear strength averaged 17 times greater than in the summer. Spring values of this index averaged approximately twice those of summer. Results suggest that Ontario soils are much more susceptible to erosion under thaw and spring conditions than later during the growing season. Soil water content and soil warming may affect the re-establishment of resistance to erosion in soils rendered erodible by freezing, thawing, and saturation. Key words: Erodibility, shear strength, aggregate stability
RATES OF CALCIUM CARBONATE REMOVAL FROM SOILS
Authors: BREEMEN N. VAN , PROTZ R.
Published: March 2010

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
SOIL COMPACTION EFFECT ON PHOTOSYNTHESIS, ROOT ROT SEVERITY, AND GROWTH OF WHITE BEANS
Authors: TU J. C. , TAN S. C.
Published: March 2010

The effect of soil compaction on photosynthesis, plant growth and root rot severity of white bean was investigated in a controlled environment using healthy and root rot diseased soil. There was a highly significant reduction in root biomass, shoot growth and total leaf area of plants grown in compacted soil. Soil compaction also significantly reduced photosynthetic rate and increased root rot severity. The reduction in growth for plants subjected to soil compaction is attributable partly due to a decrease in photosynthetic rate and to an increase in root rot severity. Key words: Phaseolus vulgaris L., Fusarium root rot, bean (white)
IMPACT OF ELEMENTAL SULFUR FERTILIZATION ON AGRICULTURAL SOILS. I. EFFECTS ON MICROBIAL BIOMASS AND ENZYME ACTIVITIES
Authors: GUPTA V. V. S. R. , LAWRENCE J. R. , GERMIDA J. J.
Published: March 2010

This study investigated the impact of repeated application of S° fertilizer on microbial and biochemical characteristics of two Grey Luvisolic soils. The Waitville pasture plots received Agri-Sul at a rate of 22 or 44 kg S° ha−1 yr−1 for 5 yr, whereas the Loon River canola-summerfallow plots received single or double applications of Flow-able Sulfur (50 kg S° ha−1) or Agri-Sul (100 kg S° ha−1). Application of S° fertilizer significantly decreased the pH in both soils. Organic C declined in S°-treated plots of the Waitville soil, and there was a narrowing of C:N:S ratios in both soils. Application of S° fertilizer significantly increased the total S, HI-S and sulfate sulfur levels of both soils. There was a 29–45% and 2–51% decline in microbial biomass carbon content due to S° fertilizer application in Waitville and Loon River soils, respectively. Repeated application of S° also resulted in a decline in respiration, dehydrogenase, urease, alkaline phosphatase and arylsulfatase activities, along with populations of protozoa, algae and nitrifiers in both soils. Significant correlations observed among related characteristics further emphasized the treatment effects. These results indicate that the impact of repeated application of S° fertilizer on microbial biomass and activity should be considered when recommending S° as a fertilizer for sulfur-deficient soils. Key words: Sulfur (elemental), microbial biomass, dehydrogenase, urea, phosphomonoesterases, arylsulfatase
IMPACT OF ELEMENTAL SULFUR FERTILIZATION ON AGRICULTURAL SOILS. II. EFFECTS ON SULFUR-OXIDIZING POPULATIONS AND OXIDATION RATES
Authors: LAWRENCE J. R. , GUPTA V. V. S. R. , GERMIDA J. J.
Published: March 2010

Effects of elemental sulfur fertilization on sulfur-oxidizing populations, rhodanese activity, total sulfur content and sulfur oxidation rates in the 0- to 15-cm zone of two Grey Luvisolic soils were assessed. Heterotrophic sulfur oxidizers were the most abundant sulfur oxidizers detected in both soils. Elemental sulfur fertilization caused an increase in populations of autotrophic thiosulfate-oxidizing micro-organisms, and a threefold increase in rhodanese and sulfur-oxidizing activity in a Waitville soil. In contrast, sulfur fertilization did not stimulate autotrophic thiosulfate oxidizers in a Loon River soil and the greatest increase in rhodanese and sulfur oxidation rates was only 31%. The response to sulfur application was biphasic however, and subsequent additions of sulfur fertilizer resulted in a decline in oxidation rates. Total sulfur content of sulfur-treated soils indicated that most of the sulfur applied was still present in the sampled zone. These results imply that prediction of sulfate release and fertilizer efficiency will be difficult to assess. Key words: Sulfur (elemental), S-oxidation, oxidation rates, rhodanese, sulfur-oxidizing micro-organisms
FREEZE-THAW EFFECTS ON GRANULAR STRUCTURE REORGANIZATION FOR SOIL MATERIALS OF VARYING TEXTURE AND MOISTURE CONTENT
Authors: PAWLUK S.
Published: March 2010

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
PREDICTING NET NITROGEN MINERALIZATION OVER A GROWING SEASON: MODEL VERIFICATION
Authors: CAMPBELL C. A. , JAME Y. W. , JONG R. DE
Published: March 2010

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
DINITROGEN FIXATION OF LENTIL, FIELD PEA AND FABABEAN UNDER DRYLAND CONDITIONS
Authors: BREMER E. , RENNIE D. A. , RENNIE R. J.
Published: March 2010

Annual grain legume production has increased substantially in Western Canada over the past 15 yr but more information on the N2-fixing potential of these crops is needed. 15N isotope dilution was used to determine N2 fixation of several grain legumes under dryland field conditions in Saskatchewan. Two cultivars of lentil (Lens culinaris Medik), pea (Pisum sativum L.), and fababean (Vicia faba L.) were grown at five locations in both 1984 and 1985, with all major soil zones represented by at least one location in each year. Drought stress was moderate to severe at all sites in 1984 and at sites in the Brown and Dark Brown soil zones in 1985. Barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) were nearly identical as non-N2-fixing reference crops, but their validity as reference crops for the grain legumes included in this study was not tested. Indigenous rhizobia were incapable of supporting adequate levels of N2 fixation at most sites in this study. Inoculation increased total dry matter, total N and N2 fixation of all grain legume cultivars tested. Proportion of N assimilated from the atmosphere declined with increasing soil nitrate levels and increasing drought stress. Annual rates of N2 fixation were as high as 75, 105 and 160 kg N ha−1 for lentil, pea and fababean, respectively, at sites in the Gray and Gray-Black soil zones in 1985, but declined by an average of 5.3, 7.6 and 10.5 kg N ha−1, respectively, for every cm reduction in moisture use. Maximum rates of N2 fixation in 1984 were about 80 kg ha−1. Fababean fixed the most N2 under wetter conditions, while pea and lentil fixed the most under drought stressed conditions. Key words: 15N isotope dilution, dinitrogen fixation, lentil, pea, fababean, drought stress
CARACTÉRISTIQUES DES SOLS SULFATÉS ACIDES DE LA SÉRIE DE L'ANSE EN MILIEU ESTUARIEN (QUÉBEC)
Authors: KIMPE C. R. DE , LAVERDIERE M. R. , BARIL R. W.
Published: March 2010

Acid sulfate soils were sampled according to the transect method in four bays along the south shore of the St. Lawrence river to determine their properties in their area of distribution. In each bay, six profiles of cultivated soils were sampled along a transect perpendicular to the river. One non-cultivated profile was also sampled at l'Isle-Verte. The lower limit of the B horizons, between 79 and 89 cm, suggested a homogeneous development of these soils across the area. Most profiles contained jarosite in the lower Bg and, sometimes, in the C horizons; this mineral was absent in the upper part of the profiles of soils that had been limed prior to cultivation. Total S content increased with depth, but only a few horizons had a content > 0.75% presumably because of sulfate leaching once the soils were drained. Organic C content in the de l'Anse soils decreased less rapidly with depth than in other gleysolic soils, because vegetation grew while sediments were being deposited. Key words: Acid sulfate soils, total S, recent marine sediments, jarosite
CHANGES IN SOIL WATER REGIME AFTER PIPELINE CONSTRUCTION IN SOLONETZIC MIXED PRAIRIE RANGELAND
Authors: NAETH M. A. , BAILEY A. W. , CHANASYK D. S. , McGILL W. B. , HARDIN R. T.
Published: March 2010

A study was conducted in the Solonetzic mixed prairie rangeland of southern Alberta to evaluate soil water responses to pipeline construction. Five adjacent natural gas pipelines on a series of rights-of-way (ROW) were studied at three sites. The pipelines were installed in 1957, 1963, 1968, 1972 and 1981. Soil water contents were monitored throughout the year using a neutron probe. Water-holding capacity of the soil was determined using the pressure-plate extraction method. Pipeline construction in Solonetzic mixed prairie ecosystems caused total soil water to a depth of 50 cm in the trench to increase over that in the undisturbed prairie. There were no significant effects on available water capacity. Berm construction over the trench impeded overland flow, particularly during springmelt, causing short periods of ponding. Construction activity had no significant effect on total water within zones of a given ROW. Soil water status was affected for a short period of time with a trend towards predisturbance conditions within 10 yr. Key words: Pipelines, Solonetzic soils, rangeland, reclamation, soil water
PENETRATION RESISTANCE TO CHARACTERIZE THE DEPTH AND PERSISTENCE OF SOIL LOOSENING IN TILLAGE STUDIES
Authors: CARTER M. R.
Published: March 2010

Soil penetration resistance was used to characterize tillage-induced changes in soil strength, as a functon of soil depth and time, under three reduced tillage systems and a deep tillage study in loam to fine sandy loam, Podzolic and Luvisolic soils. The penetration resistance measurements quantified the depth, degree, and persistence of soil loosening, and potential soil rooting depth in regard to tillage system. Mouldboard ploughing provided a greater degree of soil loosening than chisel ploughing. The potential soil rooting depth of 33 – 36 cm under mouldboard ploughing was decreased to 26 cm under both direct drilling and shallow tillage. Use of a slant-legged subsoiler (i.e., “paraplow”) prior to direct drilling prevented the reduction in soil rooting depth. The depth of soil loosening gradually declined by 30 and 60%, over a 5-mo period, under mouldboard ploughing and the "paraplow" direct drilling system, respectively. Residual tillage effects and soil compaction after deep loosening were quantified by the penetration resistance measurements. The use of penetration resistance to rapidly screen soil depth to critical levels of soil strength demonstrated that under sequential direct drilled systems soil loosening should occur on a regular basis to maintain optimum soil structure on fine sandy loam soils. Key words: Soil strength, penetration resistance, reduced tillage, Podzolic soil, Luvisolic soil
EFFECTIVENESS OF MANURE AND COMMERCIAL FERTILIZER IN RESTORING PRODUCTIVITY OF AN ARTIFICIALLY ERODED DARK BROWN CHERNOZEMIC SOIL UNDER DRYLAND CONDITIONS
Authors: DORMAAR J. F. , LINDWALL C. W. , KOZUB G. C.
Published: March 2010

A field was artificially eroded by levelling in 1957. Continuous cropping to barley for 7 yr followed by a wheat-fallow rotation for 14 yr without nutrient application did not significantly improve the soil productivity of severely "eroded" land. Subsequently, a wheat-fallow experiment was conducted from 1980 to 1985 to determine the effects of 30 Mg ha−1 feedlot manure or 150 kg commercial fertilizer N (as urea) + 150 kg commercial fertilizer P (as triple superphosphate) ha−1 on restoring the productivity to soil from which 10–20 cm or 46+ cm of soil had been removed. The manure and commercial fertilizer treatments essentially restored productivity within the first year, as measured by wheat yields, regardless of severity of erosion. During years of drought stress which often occur under dryland conditions, the manure application on the "eroded" soil treatments resulted in yields greater than those on check or fertilized plots. The manure significantly increased the organic matter, total N, NO3-N, available P, and water-stable aggregate status of the soil. There was a decrease in the difference in carbohydrates between undisturbed and 'eroded' plots from 1982 to 1984. Key words: Soil erosion, manure, commercial fertilizer, topsoil loss, soil organic matter, productivity
MEASUREMENT AND SIGNIFICANCE OF CELLULOSE IN PEAT SOILS
Authors: BROWN ANN , KAURI TIIU , KUSHNER D. J. , MATHUR S. P.
Published: March 2010

The degree of decomposition of 30 organic soils from southern Superior Province of the Precambrian Shield was investigated by comparing the cellulose component, measured as glucose in the acid hydrolysate, with the aerobic respiration rate and with the rubbed fiber content of the soils. Bivarient analyses of these parameters show reasonable correlation. It is suggested, therefore, that cellulose determination is suitable for assessing the biodegradation potential of organic soils. The method is quantitative and less subject to operator error and variability than the fiber determinations, and more rapid and reproducible than measurement of carbon dioxide produced by respiration. Key words: Cellulose, peatlands, organic soils, respiration rate, degree of decomposition
YIELDS OF WHEAT IN ROTATION WITH MAIZE AND SOYBEANS IN ZAMBIA
Authors: MUNYINDA K. , O'HALLORAN I. P. , KARAMANOS R. E.
Published: March 2010

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
SPHAGNUM AND CELLULOSE DECOMPOSITION IN DRAINED AND NATURAL AREAS OF AN ALBERTA PEATLAND
Authors: LIEFFERS V. J.
Published: March 2010

A 50-ha area of a forested peatland in north central Alberta was drained in 1984. The average water table height 5 m from the drainage ditch was 36 cm lower than in the adjacent natural peatland. This was reflected in lower substrate moisture content at both 10- and 30-cm levels in the drained area. Temperatures at 10- and 30-cm levels in the drained area peaked at 14.6 and 11.8 °C, respectively, compared to 11.7 and 9.2 °C in the natural site. In both the drained and natural areas, loss of mass of cellulose and Sphagnum samples from nylon mesh bags after 1 yr was high compared to reported studies. The drained area had greater reduction in mass than the natural site for both cellulose and Sphagnum, at the 30-cm levels. The differences were largest for cellulose where loss was 80.8% in the drained peatland compared to 48.6% in the natural site. Key words: Peatland, mire, decomposition, drainage, temperature
PHYSICAL AND CHEMICAL PROPERTIES OF A PODZOL (UPLANDS SERIES) WITH TONGUING B HORIZON
Authors: WATTERS ROBERT J. , PRICE ANTHONY G.
Published: March 2010

Observations of a Humo-Ferric Podzol within a mixed deciduous forest in central Ontario showed vertical penetration of the parent C horizon by a tonguing Bf layer to depths greater than 2.5 m, in numerous localized areas of the soil. The tonguings were possibly initiated as white pine root casts formed by windthrow or in situ decay of undisturbed taproots. The role of these tonguings in the movement of water and solutes through the soil was assessed by comparing the physical and chemical properties of tonguing (Bf) and parent C2 horizons. In terms of the physical properties, there are only two distinct layers in the profile (the A + B and the BC + C1), while for CEC, organic matter and soil pH, there are four horizons (A, B, BC, and C1). The data suggest that tonguings are major conduits for water and solutes moving through the soil, and that processes such as nutrient cycling are concentrated within the tonguings, with little activity in adjacent C horizons. Key words: Podzol, tonguing, acidification
AN INVESTIGATION ON THE DEPENDENCE OF THE GAPON COEFFICIENT ON EXCHANGEABLE SODIUM BY THREE LINEAR TRANSFORMATIONS
Authors: EVANGELOU V. P. , COALE F. J.
Published: March 2010

Based on theorical considerations of ideal exchangers, the traditional Gapon exchange selectivity coefficient (KG) is generally not expected to remain constant for exchangeable sodium ratio (ESR) greater than 0.20. Therefore, the ESR-SAR (SAR=sodium adsorption ratio) relationship is only expected to be linear and predictable for this limited range of exchange sites. The purpose of this study is to demonstrate that for some soils and/or clay minerals, which are considered nonideal exchangers, the KG may remain constant for ESR values greater than 0.20. This information is important for the reclamation of sodic soil systems with ESR > 0.2 to near Na+ saturation. Experimental data in the literature is most often limited in the ESR range of 0 – 1. Experimental Na+-Ca2+ exchange data for each of a number of soils and clay minerals were plotted according to three linear transformations of the Gapon expression in order to determine if a particular soil or clay mineral exhibits a constant Gapon exchange selectivity coefficient (KG) for ESR values significantly greater than 0.20. The three linear transformations are represented by plots of (1) 1/ExNa vs. 1/SAR, (2) ExNa vs. ExNa/SAR and (3) SAR/ExNa vs. SAR (ExNa = exchangeable Na). From the three plots employed, the ExNa vs. ExNa/SAR and the SAR/ExNa vs. SAR were shown to be the most applicable in predicting a constant KG for ESR values greater than 0.20. It is also shown that some generally low CEC materials may exhibit a constant KG for ESR values significantly greater than 0.20. These data also infer that for a particular soil the linearity of the widely used ESR-SAR relationship introduced by the U.S. Salinity Laboratory Staff may not be limited to an ESR value of 0.20. Key words: Exchangeable sodium percentage, sodium adsorption ratio, thermodynamics of cation exchange, adsorption maxima, ion affinity constants.
DECOMPOSITION OF WHEAT STRAW AND STABILIZATION OF MICROBIAL PRODUCTS
Authors: VORONEY R. P. , PAUL E. A. , ANDERSON D. W.
Published: March 2010

This research examined the effects of soil environment on the decomposition of cereal crop residues and stabilization of microbial products in the field. Microplots at semi-arid and subhumid field sites were amended with 14C-, 15N-labelled wheat straw and with 14C-labelled glucose plus 15N-labelled NH4NO3 and the fate of the residual C and N was monitored over 10 yr. Mineralization of C and N derived from wheat straw was greater at the site in the more moist environment in the short term (2 yr). In the long term (up to 10 yr), however, the residual C and N at this site decayed at a slightly slower rate, providing evidence of stabilization of organic material in chemically resistant forms, as compared to possible physical protection in the semi-arid clay-textured soil. The total recovery of labelled N was 22.5–24% in the harvested crops with 13.4–16% remaining in the surface soil by the end of the study. Mineralized labelled organic N was used with an efficiency ranging from 32 to 51%. However, after summer fallow the crop apparently used mineralized labelled N with an efficiency of only 7%. This study showed that moistness of the soil environment has a considerable effect on residue decomposition. Stabilization of humic material derived from residues relates more to the recalcitrance of microbial products and their interactions with soil mineral colloids than to the nature of the original residue. Key words: Mineralization rates, crop residues, microbial turnover, chemical recalcitrance, physical protection, plant N use-efficiency
SOIL EROSION FROM AGRICULTURAL LAND IN THE LAKE SEMCOE–COUCHICHING BASIN, 1800–1981
Authors: WILSON JOHN P.
Published: March 2010

Soil losses from agricultural land in the Lake Simcoe–Couchiching Basin between 1800 and 1981 are estimated with the universal soil loss equation (USLE). Existing methods and data are used to estimate and combine the six USLE factors with one exception. A new method that is consistent with the USLE slope definitions was developed and used to estimate the topographic factor. The results of the present study add to earlier erosion assessments because they describe the erosion hazard throughout the basin from the first days of forest clearance and agricultural settlement to the present. In particular, they indicate that soil loss rates on agricultural land have gone almost full circle from high to low and back to high rates in the past 130 yr. This result indicates the need to continue our search for permanent and more viable systems of land use. Key words: Soil erosion, potential soil loss, regional assessment
PRELIMINARY IDENTIFICATION OF SOIL SEPARATES ASSOCIATED WITH FALLOUT 137Cs
Authors: MAULÉ C. P. , DUDAS M. J.
Published: March 2010

A soil sample, from an accretionary environment, high in 137Cs activity, was fractionated into exchangeable cations, organic-rich material, and sand, silt, and clay separates to determine the partitioning of 137Cs activity. Most of the 137Cs activity was associated with separates containing organic matter. About 21% of the 137Cs activity consisted of exchangeable cesium while 51% of the activity was associated with organic-rich silt to sand-size separates. Results of this study have relevance to the use of this radionuclide for estimating soil erosion. Key words: Fallout cesium, soil separates, clays, organic matter, humic material
IDENTIFICATION OF SUBSURFACE DRAIN LOCATIONS WITH GROUND-PENETRATING RADAR
Authors: CHOW T. L. , REES H. W.
Published: March 2010

Ground-penetrating radar (GPR) is a geophysical tool designed for subsurface probing of materials with contrasting dielectric properties. The applicability of this technique to locate agricultural drain tiles or tubes under some soil types and moisture conditions found in New Brunswick and Nova Scotia was evaluated. A method using GPR graphical outputs from adjacent, paired parallel traverses was developed to verify tile drain signatures. Over 50 drains, installed from 1 to 50 years ago, in soils developed in morainal till, glaciofluvial, and glaciomarine deposits were detected with the GPR system and confirmed by excavation. These included both clay and plastic drains. With experience, reliability was found to be close to 100%. The possibility of using the system for determining depth to the drain is also discussed briefly. Key words: Ground-penetrating radar, tube drain location, apparent dielectric constant, propagation time, electromagnetic wave, propagation velocity
THE EXTRACTION OF ORGANIC MATTER FROM SELECTED SOILS AND PARTICLE SIZE FRACTIONS WITH 0.5 M NaOH AND 0.1 M Na4P2O7 SOLUTIONS
Authors: SCHNITZER M. , SCHUPPLI P.
Published: March 2010

Organic matter (OM) in the Bainsville and Melfort soils, and in coarse clay and medium silt fractions separated from these soils, was extracted under N2 with 0.5 M NaOH and unadjusted 0.1 M Na4P2O7 solutions. pH ranges of the soils and fractions in contact for 24 h with 0.5 M NaOH and 0.1 M Na4P2O7 solutions extended from 12.2 to 12.6 and 9.0 to 9.4, respectively. Slightly greater proportions of the soil-carbon were extracted by 0.5 M NaOH than by 0.1 M Na4P2O7 solution. The differences, however, did not appear to be significant and may vary from soil to soil. The efficiency of extraction and the characteristics of the extracted materials were assessed on humic acids (HAs), which were isolated from the extracts. From the Bainsville soil and fractions, 0.1 M Na4P2O7 solution extracted more high-molecular weight and more deeply colored HAs than did 0.5 M NaOH solution. But HAs extracted from the Melfort soil and fractions had similar molecular weights and colours. 13C NMR spectra showed that HAs extracted by 0.1 M Na4P2O7 solution tended to be more aromatic than HAs extracted by 0.5 M NaOH solution. Well defined solid-state 13C NMR spectra of HAs, containing up to 69.0% ash, could be recorded. Unadjusted 0.1 M Na4P2O7 solution under N2 was found to be an attractive alternative to 0.5 M NaOH solution as an extractant for soil OM. Key words: Humic acids, E4:E6 ratios, IR spectra, 13C NMR spectra, aromaticity
FORMS AND HYDROLYTIC BEHAVIOR OF SULPHUR IN HUMIC ACID AND RESIDUE FRACTIONS OF FOUR PEATS FROM THE FRASER LOWLAND
Authors: LOWE L. E. , BUSTIN R. M.
Published: March 2010

Humic acid (HA) and alkali-insoluble residue fractions (Residue) were isolated from four types of peat from the Fraser River Delta area. The peat fractions were characterized with respect to sulphur forms and response to acid hydrolysis. Total S content of HA fractions ranged from 0.3 to 5.5% on an ash-free basis, with 69–83% in C-bonded S form. Nitrogen: sulphur ratios varied between 0.64 and 5.9. The highest S contents and lowest N:S ratios were associated with peats formed under the influence of brackish water. Similar patterns were observed for the Residue fractions. Only small proportions of S (7.9–17.3%) were recovered in soluble form from the peat fractions after acid hydrolysis, and hydrolysis was accompanied by S losses attributed to volatilization. On average 4% of the initial C-bonded S was recoverable in that form in the hydrolysates, whereas 46% of the initial organic sulphate appeared in the hydrolyzate in sulphate form. The low recovery of S in hydrolyzates indicated a correspondingly small contribution of S-amino acids to the C-bonded S fraction. The large proportions of sulphur and carbon resistant to hydrolysis indicated a rather high degree of chemical (and perhaps biological) stability. Key words: Sulphur forms, hydrolyzable-S, peat humic acid, gyttja, peat fractions
EFFECTS OF PIPELINE CONSTRUCTION ON CHERNOZEMIC AND SOLONETZIC A AND B HORIZONS IN CENTRAL ALBERTA
Authors: LANDSBURG S.
Published: March 2010

The effects of pipeline construction on agricultural soil quality ratings were evaluated for the A and B horizons of Orthic Dark Brown Chernozem and Dark Brown Solonetz soils at three sites in Central Alberta 1 wk after construction. At each site, samples of the Ap horizon from the spoil side, trench, and work side portions of a pipeline right-of-way were compared to a sample of the Ap horizon from an adjacent area unaffected by pipeline construction. Spoil material below replaced topsoil on the trench was compared to a sample of an undisturbed B horizon. Regardless of soil type or land use, construction had no effect on the Ap horizon on the work side. This was due to optimum weather conditions during construction; low rainfall resulted in lack of soil rutting and minimal soil mixing. For both soil types under cultivation, construction increased soluble salt concentrations in the Ap horizons on the spoil side due to mixing of topsoil and spoil materials. There were few effects on the Ap horizon on the spoil side in pasture land, due to trench only topsoil stripping and easy spoil removal from a well-developed sod layer. Both the Ap and spoil from the trench in the Dark Brown Solonetz had increased salt concentrations, while there were few changes in the Dark Brown Chernozem. Mixing of topsoil and spoil material, and bringing salt-enriched material to the spoil surface are thought to be reponsible for the increase. For both soils and land uses, soil effects due to construction were reflected in the Ap horizon of the trench and spoil side by changes in pH, electrical conductivity, soluble salts and bulk density. Even with the increases in the soil properties monitored, the results indicated that regardless of soil type or land use, pipeline construction did not significantly affect the agricultural soil quality of the A and B horizons. Key words: Pipeline construction, solonetz, chernozem, work side, trench, spoil side
SULFATE RETENTION IN SOME PODZOLIC SOILS OF THE SOUTHERN LAURENTIANS, QUEBEC
Authors: COURCHESNE F. , HENDERSHOT W. H.
Published: March 2010

Sulfate sorption and desorption as a function of pH were measured for six podzolic horizons from two forested watersheds of the southern Laurentians. The results showed a rapid increase in sulfate sorption with decreasing pH to a maximum sorption capacity at pH values between 3.8 and 4.2 depending on the horizon considered. Below this pH retention decreased except for the Coniferous (Con) B horizon where sorption remained almost constant. This drop in the sorption capacity of the soils is related to the partial dissolution of Al, and possibly Fe, surface coatings. Levels of up to 15.9 mmol L−1 of total dissolved Al were measured at pH 3.0 for the Herminc (Her) B horizon. The amount of sorbed and total native sulfate and the maximum sorption during the experiment are positively correlated (R2 = 0.986, 0.982 and 0.800) with the oxalate extractable Al content of the soils. Except for the Con B horizon, amorphous plus crystalline Fe make up the bulk of the inorganic coatings in all six horizons. For the Con B horizon, which has the highest sorption capacity of the horizons tested, the composition of these coatings is dominated by Al materials. In all soils, the variations in sulfate sorption as a function of solution concentration are best described by the Gunary equation in the range of pH values tested. Key words: Sulfate, pH-dependent sorption, dissolution, Podzol
DISSOLUTION DES COMPOSÉS FERRUGINEUX ET ALUMINEUX DES HORIZONS B PODZOLIQUES DE SOLS DU QUÉBEC PAR LE DITHIONITE-CITRATE-BICARBONATE, L'OXALATE, LE PYROPHOSPHATE ET LE TÉTRABORATE
Authors: PAGÉ F. , KIMPE C. R. DE
Published: March 2010

Organic matter, Fe and Al were determined in dithionite-citrate-bicarbonate (d), oxalate (o), pyrophosphate (p) and tetraborate (t) extracts from Quebec Podzolic B horizons in order to evaluate the ability of these reagents to extract the organo-metallic complexes as well as inorganic oxides and hydroxides, and to verify the appropriateness of soil classification criteria. Dithionite solubilized most of the Fe whereas oxalate extracted most of the Al compounds; the ability of the same reagents to extract Al and Fe, respectively, was directly related to the amount of organo-metallic complexes. Pyrophosphate extracted not only complexes but also inorganic compounds while tetraborate extracted mainly complexes. Organic matter extraction by dithionite, oxalate and tetraborate was enhanced by a high fulvic acid content; it was highest in the Bh and lowest in the Bf horizons. Organic matter, Fe and Al extraction by tetraborate was reduced in the presence of a large Fe-inorganic compounds content. These results indicated that extracting ability of the reagents depends on the nature of the B horizons, except for Fe extraction by dithionite and Al extraction by oxalate. Consequently, Fe and Al extraction by pyrophosphate or tetraborate is not appropriate for classification purposes. Differentiation of Bh horizons from other Podzolic B horizons was possible by using the total organic C to Fed + Alo ratio, because the ratio was > 3 for Bh horizons and < 3 for Bf and Bhf horizons. Key words: Organic matter, iron, aluminum, Podzolic B horizons, extraction reagents
EFFECT OF ZINC FERTILIZATION ON PLANT ZINC CONCENTRATION OF FORAGES AND CEREALS
Authors: GUPTA UMESH C.
Published: March 2010

Field experiments were conducted in Prince Edward Island (P.E.I.) to determine the effects of Zn (zinc sulfate) applied to the soil; applied as a foliar spray; and the effects of chelated Zn applied as a foliar spray on Zn concentration of alfalfa (Medicago sativa L.), ryegrass (Lolium multiflorum Lam.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). Plant tissue Zn levels as low as 12 mg kg−1 in forages, 14 mg kg−1 in cereal boot stage tissue and 19 mg kg−1 in cereal grain were not related to Zn deficiency. Tissue Zn levels as high as 123 mg kg−1 in barley boot stage tissue and 153 mg kg−1 in alfalfa did not result in yield reduction or any Zn toxicity symptoms. Cereal and forage yields were not affected by Zn treatments. In most cases, soil and foliar Zn applications were effective in increasing the Zn concentration in forages and cereals. Should a Zn deficiency be suspected (either from the crop or animal nutrition viewpoint) Zn could be applied to the soil at 20 kg ha−1 or as a foliar spray at 0.5 to 1.0 kg ha−1 to overcome the problem in this region (and in other areas with similar soil and climatic conditions). Key words: Plant Zn, soil and foliar applied Zn, Zn chelate and zinc sulfate, podzol soils
INFLUENCES OF SEASONAL TEMPERATURE ON NITROGEN AND SULFUR MINERALIZATION/IMMOBILIZATION IN A MAPLE-BIRCH FOREST FLOOR IN CENTRAL ONTARIO
Authors: FOSTER N. W.
Published: March 2010

Net mineralization of sulfur (S) and nitrogen (N) and nitrification in an F(Oe) horizon were examined over a 16-wk period (May to September) with (a) buried bags, (b) lysimeters and (c) closed flasks at 10, 20 or 30 °C. The amount of [Formula: see text] plus [Formula: see text] extracted from soil held at 33 kPa tension over 16 wk, when extrapolated to the mass of soil in the field, was 30 kg ha−1 N and 9 kg ha−1[Formula: see text] at constant 20 °C in the flasks, and 33 kg ha−1 N and 4 kg ha−1[Formula: see text] in buried bags (mean daily temperature 15.2 °C). On the basis of lysimeter data there was a net release of only 8 kg ha−1 N and a net retention of 3 kg ha−1[Formula: see text] under field conditions, with fluctuating temperature and moisture and actively absorbing roots. Nitrate recovered from the three types of experiment was equivalent to 18, 36, and 4 kg ha−1 N, respectively. Mineralization appeared to be particularly sensitive to temporal changes in average daily temperatures in the field. The late-summer peak in mean daily forest-floor temperature triggered a shift from net mineralization to net immobilization of N. Key words: Soil temperature, forest floor, sulfate, ammonium, nitrate