bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating phosphorus loading from repeated manure applications to two Saskatchewansoils
Authors: Stumborg C. , Schoenau J J
Published: April 2011

An understanding of the impact of repeated manure additions on soil phosphorus (P) is needed to determine appropriate manure application rates for prairie soils and manure sources. The objective of this study was to assess the loading of manure-derived phosphorus using P budgets and soil P measurement techniques applied to two Saskatchewan soils with known histories of manure application. Liquid hog manure (LHM) and solid cattle manure (SCM) treatments were applied annually over 8 yr to Black Chernozemic soils (Dixon site), and LHM was applied to Dark Brown Chernozemic soils (Plenty site) over 6 yr. Soil samples were collected in the spring of 2003 and 2004 and analyzed for labile P (Modified Kelowna extractable, Olsen extractable, water extractable, and Plant Root Simulator exchange resin methods) and total P. The P budgets were in good agreement with the observed patterns in labile soil P at the two sites. The annual application of LHM (37000 L ha-1 yr-1) at agronomic nitrogen (N) rates with no additional P fertilizer (Dixon only) did not significantly elevate soil labile P compared with the unfertilized controls at both Dixon and Plenty. The annual application of SCM (7.6 Mg ha-1 yr-1) at agronomic N rates did not significantly elevate soil labile P compared with the unfertilized control at Dixon; whereas of SCM at higher rates (15.2 Mg ha-1 yr-1 and 30.4 Mg ha-1 yr-1) showed some elevation in labile soil P. Measures of labile P were sensitive to P surpluses or deficits predicted by P balances, and all methods of measuring labile soil P were strongly correlated with one another at both sites (r ≥ 0.803 at P ≤ 0.01). Key words: Manure, cattle manure, nitrogen, phosphorus, soil test phosphorus
Impact of chipping residues and its leachate on the initiation and growth of aspen root suckers
Authors: Landhäusser Simon M , Lieffers Victor J , Chow Pak
Published: April 2011

Field chipping operations often disperse chipping residues of bark and branches in layers or piles in cut-overs. We tested the effects of these residues on the root sucker regeneration of aspen (Populus tremuloides Michx.), using root systems established in large pots. After decapitation of the stems, the root systems were covered with a 4 cm thick layer of chipping residues. Other root systems were treated with an extract of the water-soluble compounds leached from a similar amount of residues while others were left untreated as controls; all three treatments were left to sucker for 7 wk. There were no differences in the number of root suckers that were initiated on the aspen root system among the three treatments. There were, however, significantly lower numbers of suckers that emerged through the chipping residue and their emergence was delayed relative to the other treatments. The delay in emergence and the reduction in sucker numbers were likely a result of the residues acting as a physical barrier. After 7 wk, concentrations of water-soluble phenolic compounds, sugars, and carbon from the chipping residues were elevated in the soil; however, they appeared to be below a level that affects sucker emergence and development. Key words: Allelochemistry, leachate, physical barrier, Populus tremuloides, regeneration
Sensitivity analysis of alternative model structures for an indicator of ammonia emissions from agriculture
Authors: Sheppard S C , Bittman S. , Tait J. , Sommer S G , Webb J.
Published: April 2011

Ammonia (NH3) emission from agriculture is an environmental and health concern in many nations, and has trans-border impacts. Direct toxicity, terrestrial eutrophication and production of inhalable aerosols (< 2.5 µm diameter) are the specific concerns. Canada, among other northern hemisphere nations, has computed a national inventory of NH3 emissions, and a new emission inventory estimate is being prepared jointly under the National Agri-Environmental Health Analysis and Reporting Program (NAHARP) and National Agri-Environmental Standards Initiative (NAESI). However, there has been a rapid evolution in the models used, and a concomitant change in the NH3-specific data required. This paper compares several model structures and options using Monte Carlo simulation and sensitivity analysis methods. The results indicate the more recent models, that compute a mass balance of NH3 from excretion to landspreading, have tended to focus uncertainty onto the dietary efficiency of animal N nutrition. After excretion, the total ammoniacal nitrogen (TAN) in the manure contributes to NH3 emissions at each stage as the manure passes from the animal housing to storage and to landspreading. There are many variants of these processes because every farm is different, resulting in diminished sensitivity to any one NH3-loss mechanism after excretion. This finding suggests that although NH3-emission factors, the empirical data at the core of the models, are not well characterised (especially for Canadian conditions), it is at least as important to expend research effort on factors that influence TAN excretion. Results of this paper will also guide development of the NAHARP/NAESI model. Key words: NAHARP, livestock, manure, Fraser Valley, ammonium sulphate, PM2.5
Rainfall induced nitrogen and phosphorus losses from Manitoba soils
Authors: Hargrave A. P. , Shaykewich C. F.
Published: April 2011

Losses of total sediment phosphorus, total sediment nitrogen and dissolved nitrite, nitrate and ammonium resulting from natural rainfall erosion were studied in southern Manitoba during the summers of 1988–1990. Soils used were a Gretna clay, Leary sandy loam, Ryerson sandy clay and a Carroll clay loam. "Standard" erosion plots, i.e 22.13 m slope length, 4.6 m wide on a 9% slope were used. Crop management systems were 1) alfalfa, 2) corn, 3) wheat – minimum tillage, 4) wheat – conventional tillage, and 5) fallow. Nutrient losses averaged over the study period were greatest from the corn and fallow treatments, as high as 160 kg ha−1 yr−1 for nitrogen and 70 kg ha−1 yr−1 for phosphorus. Losses from wheat were intermediate. Losses from alfalfa were negligible. Most of the nutrient losses occurred with the sediment fraction, a result consistent with previous studies. Thus, nutrient loss can be estimated from a knowledge of soil loss. The amount of nutrient loss per unit soil varied with soil, and was a function of the inherent nutrient status of the soil.

Key words: Nitrogen, phosphorus, rainfall erosion, nutrients
Effects of rate, placement, and frequency of P application on yield and P content of bromegrass-red clover herbage and soil P distribution
Authors: Soon Y. K.
Published: April 2011

This study was conducted on a P-deficient Dark Grey Solod to compare the effects of the rate (0, 45, 90 kg P ha−1 cumulative), placement method (broadcast vs. banding), and frequency (preplant only vs. annually) of P fertilizer application on herbage production by a bromegrass (Bromus inermiss Leyss)–red clover (Trifolium pratense L.) mixture. The preplant broadcast application was incorporated by rototilling, and subsequent broadcast applications were topdressings. Annual applications continued for 3 yr only and dry matter (DM) yields were taken for 4 yr following the establishment year in 1991. Rate of P applied had the greatest effect on herbage yield, but its effect was influenced by the frequency of application. When P fertilizer was applied annually, herbage yields increased linearly with application rates. When P was applied preplant only, herbage yields reached a plateau with 45 or more kg P ha−1. Broadcasted P yielded slightly more than banded-in P in the first year harvest only. Annual application of 30 kg P ha−1 gave the highest cumulative herbage yield, suggesting decreasing P availability with time. This was supported by soil P analysis in 1994 and by herbage P concentrations. Herbage P concentration was significantly correlated with herbage yields of the second year and subsequent harvests. It is concluded that a preplant broadcast-incorporated application of 30 to 45 kg P ha–1, followed by at least one subsequent surface application of 30 kg P ha–1 was required for optimum herbage production by a legume-grass mixture.

Key words: Application method, P fertilizer management, bromegrass-red clover, Grey Luvisol, soil P distribution
Sulphate sorption in relation to properties of podzolic and brunisolic soils in northeastern Ontario
Authors: Bhatti J. S. , Foster N. W. , Evans L. J.
Published: April 2011

An insight into sulphate (SO42−) retention by podzolic and brunisolic soils was obtained by examining SO42− sorption by B horizons from forest soils in northeastern Ontario. The amount of water soluble and adsorbed SO42− present in the soils and the ability to adsorb additional SO42− was evaluated. Relationships between soil pH, organic carbon and different iron (Fe) and aluminum (Al) fractions with water soluble and adsorbed SO42− were examined. Using a surface complexation approach, modelling was carried out to predict the soil SO42− sorption capacity at any given pH. The potential SO42– adsorption capacity was also measured by applying adsorption equations. Both the Freundlich and Langmuir sorption isotherms gave comparative fits to the SO42− adsorption data. The soils contained small amounts of water extractable SO42− (0.1 to 0.8 mmole kg–1). There was a significant positive correlation between water extractable SO42− and organic carbon in the podzolic soils but not for the brunisolic soils. Approximately 90% of the sulphate extracted was contained in the insoluble SO42− fraction. Sulphate sorption by both soil types was most closely related to amorphous inorganic Al. In brunisolic soils, total adsorbed SO42– also had a strong positive correlation with the oxalate extractable silica fraction and a negative correlation with pH. Sulphate adsorption simulations were close to the measured values.

Key words: Soluble SO42−, adsorbed SO42−, Podzol, Brunisol, amorphous Al oxide, SO42− adsorption model
Nitrogen dynamics under greenhouse conditions as influenced by method of alfalfa termination. 1. Volatile N losses
Authors: Mohr R. M. , Janzen H. H. , Entz M. H.
Published: April 2011

Use of herbicide to terminate alfalfa (Medicago sativa L.), while reducing soil erosion, could conceivably enhance volatile N losses from alfalfa residues. A controlled environment study was conducted to determine the effect of termination method on the quantity of NH3 volatilized from residues of alfalfa. A factorial combination of two termination methods (chemical, mechanical) and two methods of residue placement (incorporated, surface applied) was applied to alfalfa. Treatments were incubated in a flow-through chamber in the greenhouse for 95 d during which NH3 and CO2 evolution was measured periodically. After 95 d, 8% of surface applied legume N was lost as NH3 in tillage treatments compared to 12% in herbicide treatments. These losses amounted to 3% and 4% of total legume N in tillage and herbicide treatments, respectively. Incorporation of alfalfa residue essentially eliminated volatile N losses. Termination method had comparatively less effect on NH3 evolution than residue placement although herbicide application tended to increase the proportion of alfalfa N lost via volatilization. Residue incorporation increased cumulative CO2 evolution regardless of termination method. Results of this study suggest that termination methods in which alfalfa residue is retained on the soil surface may result in significant volatile N losses which could diminish the fertilizer value derived from alfalfa residues. However, these N losses do not necessarily preclude the adoption of herbicide termination of alfalfa given the potential reductions in soil erosion and moisture loss which may be associated with this management practice. Key words: Volatile N losses, NH3 evolution, termination method, alfalfa, herbicide, tillage, greenhouse
Sodium carbonate inhibits emergence and growth of greenhouse-grown white spruce
Authors: Maynard D. G. , Mallett K. I. , Myrholm C. L.
Published: April 2011

Conifers are extremely sensitive to salinity and in western North America irrigation waters may contain appreciable amounts of soluble salts. The objective of this study was to assess the effect of salinity of Na-enriched irrigation water (as sodium carbonate [Na2CO3]) on the emergence and growth of white spruce (Piceaglauca [Moench] Voss). An experiment using a randomized complete block design with four replicates and five salt treatments to give solution electrical conductivity (EC) of 0, 0.5, 1.0, 1.7 and 3.1 dS m−1 was established in a greenhouse. White spruce seedlings were grown in styroblock growing trays using a sphagnum peat–perlite growing medium. Seedlings were fertilized twice a week following a fertilizer regime of a commercial tree nursery. Growth measurements, chemical analysis of the foliage, roots and growing medium were completed after 12 wk. Emergence was reduced by about 8% and growth was only 50% in the 0.5 dS m−1 (92.9 mg Na+ L−1 as Na2CO3) treatment compared with the control. Each treatment with successively higher EC resulted in a further decrease in the emergence and growth parameters. Excess internal Na+ concentration, water deficit resulting from high EC in soil solutions, and high pH of the growing medium were possible causes of the growth reduction. Nutrient concentrations other than Na did not differ among treatments except in the highest salt treatment. The presence of Na+ with CO32− as the companion anion at concentrations as low as 100 mg L−1 with an EC of 0.5 dS m−1 could potentially result in reduced emergence and growth of white spruce under greenhouse conditions.

Key words: White spruce, salt damage, container grown seedlings, sodium
Nature of uranium contamination in the agricultural drainage water evaporation ponds of the San Joaquin Valley, California, USA
Authors: Duff Martine C. , Amrhein C. , Bradford G.
Published: April 2011

Evaporation ponds used for agricultural subsurface drainage water disposal in the Tulare Lake Bed (TLB) of the San Joaquin Valley, California, USA, have elevated levels of U. Waterfowl which inhabit and forage the ponds and surrounding areas are threatened by exposure to U. The ponds, which receive irrigation drainage waters and seasonal rain, are subject to wetting and drying periods. The periods result in the accumulation of decaying algae and other organic material in surface sediments. Sediment and waters in the ponds were sampled to determine what factors control U solubility and sediment U concentrations. Data from a 1990 study conducted by Chilcott et al. in 1989 on the TLB ponds were used to help identify what factors may control U solubility. Pond sediment U concentrations decreased abruptly with depth and surface sediment U concentrations were related to dissolved Ca:HCO3 ratios. Pond algal U bioaccumulation was favored in waters with high Ca:HCO3 ratios, which had lower pH values and carbonate alkalinities than waters with low Ca:HCO3 ratios. Ponds with high salinities and high carbonate alkalinities contained the highest aqueous U concentrations relative to other TLB ponds. Sediment total organic carbon (TOC) was correlated with sediment U concentrations, suggesting that U is bound to organic matter. The source of TOC is most likely from algae deposition.

Key words: Uranium, salinity, redox potential, carbonate alkalinity, bioaccumulation, algae
Effect of composts and inorganic fertilizers on spring wheat growth and N uptake
Authors: Gagnon B. , Simard R. R. , Robitaille R. , Goulet M. , Rioux R.
Published: April 2011

The nutrient availability of composts has to be known for their safe use in crop production. A field study was carried out to assess the effect of a spring application of composts and inorganic fertilizers on spring wheat (Triticum aestivum L. 'Messier') growth and N uptake in eastern Québec (Canada). The experiment was conducted in 1994 and 1995 on two different soils: a Kamouraska clay (Orthic Humic Gleysol) and a Saint-André sandy loam (Fragic Humo-Ferric Podzol). Four composts were applied at rates of 0, 90, 180 and 360 kg total N ha−1. Inorganic fertilizers were applied at rates of 0, 50, 100 and 200% of wheat N, P or K requirements. Treatments in which inorganic fertilizers (IN) were added to composts were also included. Grain yield was increased by N rates whereas composts alone at 90 kg total N ha–1 resulted in lower yields than the control in the first year on the sandy loam. Commercial composts resulted in higher yields than dairy manure composts. Wheat showed no significant response to P and K fertilizers on either soil. Compost rates had no effect on grain N content but commercial composts increased straw N by 36 to 63%. Addition of IN to composts increased grain yield by 0.1 to 1.5 Mg ha−1 and N uptake by 4 to 55 kg N ha−1, depending on soil and weather conditions. Apparent recovery efficiency of added N for composts was −14 to 15% whereas it ranged from 24 to 56% for IN. In spring wheat production, composts should be considered more as organic matter amendments because of their limited N efficiency.

Key words: Composted dairy manure, shrimp wastes, peat moss, apparent N recovery
Influence of previous cropping practices on the response of spring wheat to applied N
Authors: Bélanger G. , Richards J. E. , Milburn P. , Walker D.
Published: April 2011

Nitrate (NO3) leaches from the rooting zone into ground waters during late fall and early spring in Atlantic Canada, particularly from soils cropped to potatoes, both in the year of potatoes and in the following year in the rotation. Therefore, it is imperative to maximize N fertilizer efficiencies in order to minimize environmental degradation. Six field trials were conducted in the upper St-John River Valley of New Brunswick to determine the effect of two previous crops, oats and potatoes, on the amount of residual NO3 in the spring following their harvest, and to determine if spring soil NO3 could be used as a single criterion to predict fertilizer N requirements of wheat. At all six field trials, spring soil NO3-N (0–0.45 m) was greater with potatoes as the previous crop (average of 86 kg NO3-N ha−1) than with oats (average of 56 kg NO3-N ha−1). As a result, the economically optimum fertilizer rate (Nop) for spring wheat was lower on soil previously cropped to potatoes (108 kg N ha–1) than oats (135 kg N ha–1). Nop, however, was poorly correlated with the amount of spring soil NO3-N. We conclude that conventional spring soil tests based on NO3-N are inappropriate to predict fertilizer N requirements of wheat in Atlantic Canada. Fertilizer N recommendations in Atlantic Canada, however, may be improved by taking previous crop into consideration. Key words: Wheat, potatoes, oats, nitrogen, previous crops
Influence of urea fertilization and urease inhibitor on the size and activity of the soil microbial biomass under conventional and zero tillage at two sites
Authors: Banerjee M. R. , Burton D. L. , Grant C. A.
Published: April 2011

Fertilizers are frequently used in agriculture to enhance crop yield and quality. Increasingly, microbial and enzyme inhibitors are being used to enhance the efficiency of fertilizer nitrogen use. The assumption being made is that the impact of these compounds is short-term or localized and thus does not adversely impact soil quality. This study investigates the implications of urea fertilizer with and without urease inhibitor [N-(n-butyl) thiophosphoric triamide, NBPT], conventional and zero tillage systems, and soil types on the soil biological characteristics including N mineralization. Microplot studies were conducted in clay loam and fine sandy loam soils in Manitoba. Soil type had a significant effect on the soil organic C but tillage did not have any significant effect. Soil microbial biomass C content ranged widely (131–1215 µg g−1 soil). The clay loam soil generally tended to contain higher biomass C than the sandy loam soil. The potential soil mineral N production (N0) was higher in clay loam soil (92.6 µg g−1 soil) than sandy loam soil (40.2 µg g−1 soil). Tillage systems, urea and urease inhibitor application had no significant impact on the soil biomass C, N0, arylsulfatase or acid and alkaline phosphatase content. At these sites considerable fluctuations occurred in the microbial and biochemical properties due to the variation of soil type. In general, these fluctuations were mainly related to soil organic matter and soil moisture content. Tillage system, urea with and without NBPT application did not contribute any notable impact on the soil biological properties reported in this study. Key words: Soil biological quality, soil type, urease inhibitor, conventional tillage, zero tillage
The influence of aspect and vegetation on seasonal changes in erosion under rainfall simulation on a clay soil in Spain
Authors: Cerdà A.
Published: April 2011

The seasonal and spatial variability of soil erosion under contrasting slope aspects in southeastern Spain was studied by performing and interpreting 84 rainfall simulation experiments conducted at an intensity of 55 mm h−1 during 1 h. The vegetated soils on the north-facing slope and the upper afforested parts had negligible sediment yield, runoff and erosion, while the bare soils on the south-facing slope had very high runoff rates. Runoff sediment concentration decreased over time during simulated rainfall events on the vegetated areas while it increased on the bare ones. Solute release decreased over time on both surface types. Seasonally, runoff sediment concentration was highest in autumn, decreasing in winter and spring, due to the exhaustion of erodible soil and the vegetation growth. Sediment concentrations increased slightly in summer when runoff and erosion rates where very low. Increasing seasonal variability corresponded with increasing runoff and soil loss rates. Key words: Runoff, soil loss, Mediterranean, erodibility
Crop yield, soil temperature and sensitivity of EPIC under central-eastern Canadian conditions
Authors: Roloff G. , Dejong R. , Nolin M.C.
Published: April 2011

The Environmental Policy Integrated Climate (EPIC) model can be an important tool for agricultural and environmental management. Application of EPIC in central-eastern Canada requires testing to evaluate its performance and to indicate eventual changes that ultimately can lead to a more accurate model. We compared crop yields and soil temperatures estimated using EPIC (version 5300) with measured data from two sites — Barrhaven, Ontario and St. Antoine, Quebec — where corn (Zea mays L.) and soybean (Glycine max L.) were grown during 4 yr. The sensitivity of several EPIC outputs to variations in selected input parameters was also determined. EPIC was run with either the Penman-Monteith (PM) or the Baier-Robertson (BR) potential evapotranspiration (PET) method. Mean estimated and measured soybean yields were not different, independent of PET method and location. Mean corn yields were underestimated at Barrhaven with the PM method, whereas they were overestimated by the BR method at St. Antoine. Using the PM method resulted in no difference between estimated and measured yields in 2 out of 5 corn years, while the BR method ensued in no difference in 3 out of 5 years. For soybean, only the BR method resulted in 1 yr of yield different than measured. Performance of the model in relation to experimental error and efficiency of the model varied with crop and location, and indicated that EPIC caused less error and was more efficient in estimating soybean than corn yields. Comparing limited measured soil temperature data with EPIC estimates reveled that EPIC tended to underestimate soil temperature; however no effect on estimated yield was observed. The relative sensitivity of EPIC outputs was least for yield and greatest for leached nitrate-N. The latter also displayed the highest variability in sensitivity. EPIC studies focusing on leached nitrate-N should require the most accurate crop, soil, hydrological and weather data in order to minimize errors. Key words: Environmental modelling, soybean yield, corn yield, sensitivity analysis
A technique to predict hourly potential solar radiation and temperature for a mostly unmonitored area in the Cape Breton Highlands
Authors: Bourque Charles P.-A. , Gullison Jeremy J.
Published: April 2011

A technique was developed to obtain predictions of potential solar radiation and temperature for a prescribed, mostly unmonitored, area in the Cape Breton Highlands region of northeastern Nova Scotia (46°39′N 60°57′W to 46°40′N 60°24′W). Hourly predictions of incoming solar radiation are based on relations of sun-earth geometry, clear-sky atmospheric transmittance, and land-surface attributes resolved from digital terrain and vegetation models. The digital vegetation model characterizes vegetation cover and is used to define the average midday albedoes for the area in question. Hourly albedoes are calculated according to assigned mid-day albedo and sun-illumination angles. Land-surface characteristics (elevation, slope, aspect, horizon angles, terrain configuration factor, and view factor) affect total incident solar radiation by affecting the direct, diffused, and reflected energy components. Hourly spatial variability in above-ground daytime temperature is captured by way of a fully trained artificial neural network (ANN) that describes hourly fluctuations of interior highland temperatures according to i) reference temperatures taken at two lowland locations, one at Ingonish Beach and the other at Grande Anse; ii) distance from a north-south line representing the east coast of the study area and from the Grande Anse location; iii) time of day; and iv) land-surface attributes. Training the ANN involves supplying the network with actual data and having the network adjust its internal weights iteratively so that the output values are sufficiently close to the supplied target values. Comparison of predicted and observed hourly spring-summer (1997) temperatures revealed that the constructed ANN explained over 88% of the variability exhibited in the observed temperatures and that the standard error of estimate was 2.0 °C (mean absolute error = 1.5 °C). Key words: Sun-earth geometry, radiation laws, variable surface albedo, clear-sky atmospheric transmissivity, digital terrain, vegetation models, artificial neural networks
Evaluation of EPIC's wind erosion submodel using data from southern Alberta
Authors: Potter K. N. , Williams J. R. , Larney F. J. , Bullock M. S.
Published: April 2011

Wind erosion models have been used to assess policy impacts on soil erosion, but validation of models has been difficult until recently. We evaluated the Environmental Policy Integrated Climate (EPIC) wind erosion submodel by comparing simulation results to field measured wind erosion sediment losses. Using standard model inputs and actual wind velocities, wind erosion was simulated for a field near Lethbridge, Alberta (49°37′N, 112°38′W) where field measurements of wind erosion were made in April 1992 on a Dark Brown Chernozemic soil. The EPIC submodel predicted erosion losses for each day that erosion was measured, and approximated the magnitude of erosion on six of the seven erosion events. EPIC significantly overestimated erosion for one event and also simulated erosion on 3 d when no erosion was recorded. Field length had a larger effect on simulation results during large erosion events than for smaller events. The effect of surface soil water content on wind erosion appeared to be captured by the model, but only limited data were available to evaluate this aspect. Other portions of the model such as the effects of surface roughness and vegetative cover could not be evaluated in this study. Key words: Field length, surface water content, sediment losses
Response of spring wheat cultivars to Glomus clarum NT4 in a P-deficient soil containing arbuscular mycorrhizal fungi
Authors: Xavier Lisette J. C. , Germida James J.
Published: April 2011

The dependency of four spring wheat cultivars (Triticum aestivum L.) Laura, Columbus, Neepawa and Katepwa on Glomus clarum NT4 in a P-deficient soil containing indigenous arbuscular mycorrhizal fungi (AMF) was assessed in a growth chamber. The wheat cultivars were grown with or without 1.5 g of a monospecific culture of Glomus clarum NT4 for 95 d. The NT4 inoculant had no significant (P < 0.05) impact on the growth or grain yield of Laura or Neepawa, but increased that of Columbus and reduced that of Katepwa. The shoot P or N concentration, or the shoot P use efficiency (PUE) was not affected by AMF inoculation. However, the grain P concentration of Laura was significantly (P < 0.05) greater in the NT4-inoculated plants compared with the control. Increases in the shoot and grain yield of NT4inoculated Columbus were associated with a significant (P < 0.05) increase in the grain PUE of the plants. The % AMF-colonized root was significantly higher in NT4-inoculated Laura, Columbus and Neepawa, but there was no effect on Katepwa. The dependency of the cultivar Columbus on AMF was apparently greater in this soil compared with the other cultivars. These results suggest that the four wheat cultivars not only varied in their susceptibility to AMF colonization, but also in their ability to exploit the rhizosphere AMF community which reflected on plant yield. Key words: Wheat cultivars, Glomus clarum NT4, AMF-cultivar interactions
Forage seed yield response to N and P fertilizers and soil nutrients in northeastern Saskatchewan
Authors: Loeppky H. A. , Horton P. R. , Bittman S. , Townley-Smith L. , Wright T. , Nuttall W. F.
Published: April 2011

There is no information on the effect, in northeastern Saskatchewan, of N and P fertilizers on forage seed production as influenced by these nutrients in the soil. Therefore, experiments were conducted at eight sites from 1988 to 1991 to determine the effect of N and P fertilizers and soil nutrients on seed yields of alfalfa (Medicago media Pers.), smooth bromegrass (Bromus inermis Leyss.), crested wheatgrass (Agropyron cristatum L.), intermediate wheatgrass (Agropyron intermedium [Host.] Beauv.) and timothy (Phleum pratense L.). Nitrogen fertilizer (urea) was applied on grasses annually at 0, 50, 100 and 150 kg N ha−1 in factorial combination with 0, 9 and 18 kg P ha−1 (monoammonium phosphate and triple superphosphate) and on alfalfa at 0 and 50 kg N ha−1 in combination with 0, 9, 18, 26 and 53 kg P ha−1. Nitrogen significantly increased forage seed yields of all species except alfalfa. Phosphorus increased yields of forage seed for all crops except intermediate wheatgrass. The site, N, P and year and their interactions influenced seed yields. Seed yields ranged from a low of 0.29 t ha−1 for smooth bromegrass in 1990, a dry year, to a high of 1.24 t ha−1 in 1989 a cool, moist year. The yield response to N and P fertilizers was affected by available soil N and P. Relative to control, the percentage increase in grass seed yield from applied N and P fertilizers was highly related to the available soil N and P (R2 = 0.93). The estimated smooth bromegrass seed yield response to 50N–9P kg ha−1 was 0.54 t ha−1 when the soil had intermediate amounts of available N and P (2 mg N ha−1 and 8 mg P ha−1, 0- to 60-cm and 0- to 15-cm depths, respectively). On a soil that tested high in available N and P, there was no response to fertilizer. Regression equations were developed that can be used to estimate forage seed yield response of different species in relation to available soil nutrients. These results are useful for estimating the most economical return on fertilizer investment for forage seed production in Saskatchewan. Key words: Forage, seed, N, P, fertilizer, soil tests, correlation
Physical properties of a Chernozemic clay loam soil under long-term conventional tillage and no-till
Authors: Miller J. J. , Larney F. J. , Lindwall C. W.
Published: April 2011

Conservation tillage practices such as no-till (NT) and conventional tillage (CT) with a heavy-duty cultivator can influence the physical properties of soils. This study was conducted to determine the effect of 24 yr of NT versus CT on the physical properties of a clay loam soil in southern Alberta. Physical properties quantified were bulk density (BD), mean weight diameter (MWD), plant-available water-holding capacity (PAWHC), saturated hydraulic conductivity (Ksat), soil water characteristic [θ(ψ)] and unsaturated hydraulic conductivity [K(ψ)] relationships, and pore-size distribution (PSD). Bulk soil samples and small soil cores (5-cm depth increments to 20 cm) were taken from CT and NT fields in 1992, and tension infiltrometer measurements were made in 1994. The results from this study are reported as general trends for the tillage fields. Statistical probability levels are not reported because of the unreplicated nature of the experiment, the limited number of sampling locations within each tillage field, and to a lesser extent, the different sampling times for CT and NT in 1992. Plant-available water-holding capacity was higher for the CT field (14.3%) than the NT field (10.8%), and a greater amount of water was held at a given water potential (−1500 to −1.5 kPa) for the former, indicating a higher potential for soil water conservation under conventional tillage. Geometric mean Ksat values (small soil cores) were higher for the NT field (18.20 × 10−6 m s−1) than the CT field (1.74 × 10−6 m s−1). The K(ψ) values (small soil cores) between −10 and −2 kPa were higher for the CT field than the NT field at the 0- to 5-cm, 10- to 15-cm and 15- to 20-cm depths, but values were higher for the NT field at the 5- to 10-cm depth. Near-saturated K(ψ) values (−1.5 to −0.3 kPa) of the surface soil, as derived from tension infiltration measurements in 1994, were higher for the CT field (2.43 × 10−7 m s−1) than for the NT field (6.09 × 10−8 m s−1). There was a greater percentage volume of larger pores (30–40, 40–67, 67–200, >200 µm) for the NT field than for the CT field, and there was a lower percentage volume of smaller pores (0.2–0.6, 0.6–4 µm) for the CT field than for the NT field. Differences in certain soil physical properties between CT and NT fields may be related to the lag time between the most recent tillage event and sampling for the CT field. Key words: Conservation tillage, heavy-duty cultivator, physical attributes, soil water, hydraulic conductivity, porosity
Protected organic matter in water-stable aggregates as affected by mineral fertilizer and manure applications
Authors: Aoyama M. , Angers D. A. , N'Dayegamiye A. , Bissonnette N.
Published: April 2011

Effects of long-term (18-yr) applications of cattle manure (20 Mg ha−1 yr−1) and NPK fertilizer on the labile organic matter (OM) and its protection in water-stable aggregates were investigated in a Le Bras silt loam (Humic Gleysol). Soil from the 0- to 10-cm depth was sampled from the untreated control, NPK, manure and NPK + manure treatments and fractionated into four size classes of slaking-resistant aggregates (>1000 µm, 250–1000 µm, 53–250 µm, <53 µm). Intact and crushed macroaggregates (250–1000 and >1000 µm) and intact microaggregates (<250 µm) were incubated for 21 d at 25 °C, and mineralized C and N were determined. The amount of mineralized C in intact aggregates increased with increasing aggregate size irrespective of the agronomic treatments, but there was no consistent trend for total N. Manure application led to an increase in mineralized C in most aggregate fractions. Crushing the macroaggregates enhanced mineralization of C by 14 to 35% and N by 17 to 103%. Additional C and N rendered mineralizable by crushing represents a fraction of the macroaggregate-protected OM. Manure application increased the protected pools of C (up to threefold) and N (up to fourfold) located in the small macroaggregates (250–1000 µm). In contrast, NPK fertilization increased the pool of macroaggregate-protected N by 2.5-fold but had no effect on the protected C. We conclude that manure application contributed to the accumulation of macroaggregate-protected C and N, whereas mineral fertilizers increased the protected-N pool only. Macroaggregates can provide a mechanism for the protection of labile soil OM in an annually tilled cropping system and this mechanism is enhanced with long-term manure application. Key words: Aggregate-protected organic matter, manure application, mineralization, mineral fertilizer, water-stable aggregates
Soil C extracted with water or K2SO4: pH effect on determination of microbial biomass
Authors: Haney R. L. , Franzluebbers A. J. , Hons F. M. , Zuberer D. A.
Published: April 2011

Routine determination of soil microbial biomass C has shifted during the past decade from chloroform fumigation-incubation to chloroform fumigation-extraction using 0.5 M K2SO4 as extractant. We compared extractable C with water and 0.5 M K2SO4 in eight soils ranging in pH from 5.4 to 8.3. In unfumigated soils with low pH, extractable C was 0.8- to 1.2-fold greater with water than with 0.5 M K2SO4. However, in unfumigated soils with pH > 7.7, extractable C, although not statistically significant, was 11 to 19% less with water than with 0.5 M K2SO4. In fumigated soils, no difference in extractable C between water and 0.5 M K2SO4 was detected among soils with pH < 7.7, but extractable C was 13 to 17% less with water than with 0.5 M K2SO4 with pH > 7.7. Our results suggest that 0.5 M K2SO4 (1) may flocculate soil and cause adsorption of solubilized C onto colloids at pH < 7.7, but (2) may disperse calcareous soils at pH > 7.7, thereby differentially affecting the fate of solubilized C depending upon soil pH. Our results put into question the widespread adaptability of using chloroform fumigation-extraction to estimate microbial biomass C. Key words: Extractable carbon, chloroform fumigation-extraction, microbial biomass
Summer rainfall recycling for an agricultural region of the Canadian prairies
Authors: Raddatz R. L.
Published: April 2011

Water vapour from regional evapotranspiration that falls again as rain within the same region is referred to as recycled rainfall. This study estimated the summer rainfall recycling ratios (i.e., the relative contribution of recycled rain to total rain) for an agricultural region of the Canadian Prairies by examining the soil water balance component of the land surface branch of the water cycle along with the atmospheric branch of the cycle for June-July-August of 1997, 1998 and 1999. Recycled rain accounted for 24 to 35% of the total rainfall. For these three summers, this study also estimated the horizontal water vapour flux divergence for the region, and compared the areal average summer evapotranspiration totals determined from land-use weighted soil water balance modelling and as residuals in the atmospheric water balance equation. The horizontal water vapour flux divergence per unit area averaged 36 mm. The mean difference between the evapotranspiration estimates was about 15%. It can be concluded, for the summers of 1997, 1998 and 1999, that: (1) regional evapotranspiration was secondary to advection, yet significant, as a source of water vapour for rainfall on the Canadian Prairies, (2) the agricultural area of the Canadian Prairies was a source region of water vapour – consistent with the arid character of the climate, and (3) the land-use weighted soil water balance estimates of areal average evapotranspiration were reasonably accurate. Key words: Water cycle, horizontal water vapour flux, evapotranspiration, atmospheric water balance, soil water balance
Seasonal response of denitrifiers to temperature in a Quebec cropped soil
Authors: Pelletier France , Prévost Danielle , Laliberté Gilles , Bochove Eric van
Published: April 2011

While some studies indicate no denitrification activity in early spring, others have demonstrated that denitrifiers from temperate region soils can adapt to low temperatures. The aim of the present paper was to study how seasonal changes in temperature affect denitrifying enzyme activity (DEA) in a cropped humic gleysol located in a cold temperate climate (Quebec). Soil was sampled monthly during a 16-mo period and DEA was measured at nine temperatures from 2 to 35°C. A seasonal effect of temperature on DEA was significant at all incubation temperatures and was more important in November and in May–June. The effect of temperature on DEA was better fitted with the square root model of Ratkowsky than with the Arrhenius equation. The regression coefficient b (Ratkowsky parameter) varied seasonally with a trend similar to that of DEA. These results show that the Ratkowsky model should be used instead of Arrhenius equation to describe the effect of cold temperature on denitrification. Key words: Denitrification, temperature, cold, Arrhenius equation, Ratkowsky model
Fertilization of a mixed forage crop with fresh and composted chicken manure and NPK fertilizer: Effects on dry matter yield and soil and tissue N, P and K
Authors: Warman P. R. , Cooper J. M.
Published: April 2011

An experiment was conducted for 3 yr to compare the effects of fertilization of mixed forage with fresh and composted chicken manure and inorganic NPK. Fertility amendments were applied each year at three N levels and an unfertilized treatment was included. The experiment was conducted in two hay fields near Truro, Nova Scotia. Dry matter yield and forage N, P and K contents are reported for the 1992 and 1993 seasons. The nutrient content of the amendments as well as the efficiency of P and K use are discussed. Soil Mehlich 3-extractable P and K and KCl-extractable N were measured at two depths in September 1993. By the final year of the experiment, compost amendments produced yields as high as the recommended rate of NPK fertilization at both sites on both harvest dates. Medium rates of compost application also resulted in tissue N levels as high as or higher than the equivalent NPK treatments. The medium rate of manure application was equivalent in yield and tissue N to the compost treatments at the Acadia site, but had slightly lower yields and tissue N content at the Pugwash site. Compost P and K were relatively inefficiently used by the forage; this resulted in increased levels of Mehlich 3-extractable P and K in the 0- to 15-cm layer of the compost-amended plots. It was concluded that fertilization with compost or inorganic NPK, supplying equal amounts of N, can result in comparable yields and quality of forage. Key words: Chicken manure, compost, extractable NPK, forage, forage NPK, plant protein
Introduction to Symposium — Microbial Biomass: Measurement and Role in Soil Quality
Authors: Franzluebbers A. J.
Published: April 2011

not available
Fertilization of a mixed forage crop with fresh and composted chicken manure and NPK fertilizer: Effects on soil and tissue Ca, Mg, S, B, Cu, Fe, Mn and Zn
Authors: Warman P. R. , Cooper J. M.
Published: April 2011

A 3-yr experiment compared the effects of the fertilization of mixed forages with fresh and composted chicken manure and NPK fertilizer. Amendments were applied at three N levels, and an unfertilized treatment was included. The experiment was conducted in two hay fields: a sandy loam and a silty clay loam, near Truro, Nova Scotia. Mehlich 3- extractable Ca, Mg, S and micronutrients were reported for two depths of soil sampled in September 1993. In most cases, the Ca, Mg, S and micronutrient levels in the chicken manure compost and fresh manure were higher than the literature values. The Cu and Zn in both the fresh chicken manure and the compost exceeded the maximum concentrations for Category A (unrestricted use) compost. Compost treatments resulted in higher Ca in the upper horizon at both sites, but few differences among treatments were noted for soil Mg or S. Extractable soil Cu was not higher in the compost and manure plots in spite of the relatively high levels of Cu in the amendments. Compost-treated plots were numerically highest in soil Zn at the silty clay site, while the NPK plots had the highest Mehlich 3-extractable Fe at the same site. Fewer differences in soil levels of micronutrients were detected among treatments at the sandy loam site. Forage tissue Ca, Mg, S and micronutrients were reported for the 1993 season. The high rates of applications, especially for compost treatments, did not always result in higher nutrient levels in the forages; other factors that may have affected nutrient availability are suggested. It is concluded that higher rates of compost and manure could have been used in this experiment without risks of phyto- or ruminant toxicity. Key words: Chicken manure, compost, forage, Mehlich 3-extractable nutrients, micronutrients
Plant residue and cropping system effects on N dynamics in a Gray Luvisolic soil
Authors: Broersma K. , Juma N. G. , Robertson J. A.
Published: April 2011

Soil samples from differing cropping systems were amended with 15N-labeled plant residues having varying carbon to nitrogen (C:N) ratios to quantify N dynamics in a Gray Luvisolic soil. For non-amended cropping systems a significantly greater amount of total N was mineralized from the continuous legume (CL) than from the continuous grass (CG), barley/forage (BF) rotations, or continuous barley (CB) cropping systems. The addition of the fababean (Vicia faba L.) plant residue resulted in net N mineralization from most of the cropping systems. After 20 wk, 14.0%, 10.5% and 7.1% of the 15N was mineralized from fababean, barley (Hordeum vulgare L.) and fescue (Festuca rubra L.) amended residues, respectively, when averaged across cropping systems. Key words: Crop residues, cropping systems, Gray Luvisol, N mineralization, 15N, soil amendments
Soil and vegetation of ungrazed crested wheatgrass and native rangelands
Authors: Broersma K. , Krzic M. , Thompson D. J. , Bomke A. A.
Published: April 2011

Seeding of introduced forage grasses, such as crested wheatgrass [Agropyron cristatum (L.) Gaertn. and A. desertorum (Fisch.) Schult.], can lead to the reduction of species diversity and soil quality. This study evaluated the effects of crested wheatgrass on soil and vegetation relative to native rangeland dominated by bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) Scribn. & Smith] under ungrazed conditions. Three sites consisting of adjacent ungrazed stands of crested wheatgrass and native vegetation were sampled in June 1997. Total plant cover was 37% on native and 24% on crested wheatgrass rangeland. Species richness was lower for crested wheatgrass than for native rangeland. Quantities of root biomass and most soil properties were similar for the two rangelands. Native rangeland had a more stable soil structure with 1.7 mm mean weight diameter (MWD) and 38% of soil aggregates in the 2–6 mm size fraction compared to 1.4 mm MWD and 28% of soil aggregate in the 2–6 mm size fraction on crested wheatgrass rangeland. Greater soil penetration resistance was observed at the 6 and 7.5 cm depths for crested wheatgrass rangeland. Crested wheatgrass did not invade adjacent native rangelands and only a slight reduction in soil quality was observed on crested wheatgrass rangelands. Key words: Crested wheatgrass, soil C, soil N, penetration resistance, aggregate stability, species diversity