bluuebunny/crossref_metadata_2025 huggingface dataset:
Effet à court terme de la mise en culture sur le statut organique et l’agrégation d’un sol ferrallitique argileux du Congo
Authors: Barthès B. , Kouakoua E. , Sala G. H. , Hartmann C. , Nyeté B.
Published: April 2011

Cultivation of oxisols of the Niari Valley (Congo) leads to considerable decline in the soil organic carbon content and structural stability in a few years. The objective of this study was to estimate the very short-term effects of cultivation on organic status and macroaggregate (> 0.2 mm) stability of a soil which had been under savanna for 20 yr. Another objective was to identify the determinants of macroaggregate stability.On one hand, after 5 mo of manual or mechanized cultivation, stable macroaggregate content MA decreased significantly in the 0- to 10-cm layer (7% on average); soil organic carbon stock S did not (6% on average), whereas the decrease in soil organic carbon content C was significant only under mechanized cultivation (13.5% on average, vs. 7% under manual cultivation). On the other hand, the influence of cultivation on MA, S and C was not significant in the 10- to 20-cm layer (variations < 5%, on average).MA was correlated with exchangeable aluminum content (r = 0.6), though its contribution to stability was low, but was neither with "free" or "amorphous" iron and aluminum contents (r < 0.3), nor with C (r < 0.1); moreover, the influence of hot water-extractable compounds on MA was not significant. Therefore, macroaggregation did not seem to be controlled by organic matter. Key words: Macroaggregate stability, soil organic carbon, oxisol, setting into cultivation, exchangeable aluminum, hot water pretreatment
Use of southern parents in a short-season soybean breeding program is facilitated with long-day screening
Authors: Cober E. R. , Tanner J. W.
Published: April 2011

Elite northern-by-southern soybean crosses may increase genetic diversity while maintaining performance. The objective of this study was to test a long-day selection method which would generate populations containing southern germplasm adapted in maturity to short-season areas. Long-daylength-insensitive lines (MG 00 to 0) were crossed to southern determinate cultivars (MG IV to VI) and of 909 F2 plants grown under 20-h incandescent long daylength (ILD), 34 were ILD-insensitive and non-dwarf. Progeny from selected ILD-insensitive plants were intermated and the resulting modified double cross F2 populations were grown in the field and were of late MG I adaptation. The ILD-screening technique was useful for generating early-maturing populations from parents with divergent maturity. Key words: Genetic diversity, long-daylength insensitivity, soybean breeding
The effect of companion crops and herbicides on economic returns of alfalfa-bromegrass establishment
Authors: Smith E. G. , Barbieri J. M. , Moyer J. R. , Cole D. E.
Published: April 2011

In moist regions and under irrigation in western Canada, there may be an economic advantage to using companion crops in forage establishment. Economic returns of establishing a mixture of alfalfa (Medicago sativa L.) and bromegrass (Bromus spp.) were determined with and without a companion crop of barley grain and silage (Hordeum vulgare L.) and with and without post-emergence herbicides at Westlock, Alberta under dryland, and with and without a companion crop of soft white spring wheat (Triticum aestivum L.) and with and without post emergence herbicides at Lethbridge, Alberta under irrigation conditions. The yearly economic benefit of companion crops was greater on irrigation than on dryland ($15 to $27 ha−1), higher for companion crops harvested for silage than for grain ($55 to $75 ha−1), and was dependent on the price of forage and grain. On dryland with medium product price levels, economic returns were 100% higher for a barley silage companion crop, and were 14% lower for a barley grain companion crop than without a companion crop. At high hay prices, returns for the barley silage companion crop were 5% higher than without a companion crop. On irrigation, the yearly economic returns with a companion crop were higher ($23 to $139 ha−1) than without a companion crop. The use of post-emergence herbicides had no long-term economic benefit for forage establishment and reduced yearly net returns $13 ha−1 on dryland and $41 ha−1 on irrigation. Key words: Companion crop, forage establishment, economics, herbicide
The inheritance of adult plant resistance to stem rust derived from wheat cultivars Bonza and Chris
Authors: Knott D. R.
Published: April 2011

The wheat (Triticum aestivum L.) cultivars Bonza and Chris have adult plant resistance to stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & Henn.) in addition to genes for specific resistance. Both cultivars were crossed to a susceptible wheat, LMPG. Lines carrying the adult plant resistances of the two parents were produced by selecting for seedling susceptibility in the greenhouse and adult plant resistance in the field to race 15B-1 (TMH). Three homozygous lines derived from Bonza and two from Chris were crossed and backcrossed to LMPG. Backcross F2 families were grown in a field nursery inoculated with a multi-race mixture of eight stem rust isolates including 15B-1. Stem rust severities in percent were recorded. An analysis of the data indicated that adult plant resistance of Bonza was controlled by a single recessive gene and that of Chris by two complementary recessive genes. Since the resistance was effective against a complex mixture of virulent stem rust races, it should be of interest to wheat breeders. Key words: Stem rust, Puccinia graminis, common wheat, Triticum aestivum, adult plant resistance
Soil erodibility relationships on drumlin deposits in the Cape Caribou River area, Labrador
Authors: Kesteren A. R. van
Published: April 2011

Universal soil loss equation (USLE) soil erodibility (K) factors were computed from drumlin soils in the Cape Caribou River area, Labrador. Soil erodibility variation was investigated, using Mann-Whitney and Kruskal-Wallis tests, for three stratifications: (i) topographic position (TOP), (ii) mineral soil horizon (HOR), and (iii) soil texture (TEX). Topographic position with two substrata, drumlin summits (SUM) and drumlin side slopes (SID), was not significant. Horizons A, B and C and textural classes loamy sands (LS), sandy loams (SL) and loams (L) were significant. A log linear likelihood chi-square (G2) model was applied to investigate relationships of HOR and TEX. Partitioning of the G2 statistic revealed both significant and non-significant cells in the cross tabulation. Some sampling considerations for the determination of K factors are discussed. It is concluded that accepted field methods could enhance K factor determination in Labrador forest soil environments. Key words: Soil erodibility, K factor, drumlins, Labrador
Seasonal distribution of runoff and soil loss under four tillage treatments in the upper St. John River valley New Brunswick, Canada
Authors: Chow T. L. , Rees H. W. , Monteith J.
Published: April 2011

The effect of four different tillage treatments on surface runoff and soil loss, their seasonal distribution and temporal variation in soil erodibility were examined using runoff-erosion plots (10 m wide × 30 m long), on a Holmesville gravelly loam soil, a major soil type used for potato production in New Brunswick. Fall moldboard plowing, fall chisel plowing, spring moldboard plowing and subsoiling followed by fall moldboard plowing were evaluated under barley and fallow conditions on 8 and 11% slopes between 1989 and 1993. With exception of one year, annual precipitation was lower than normal. However, due to higher rainfall during the cropping season, the calculated erosivities were higher than those typically used for conservation planning in this region. Runoff data revealed that fall moldboard plowing generated the highest runoff. Either performing subsoiling prior to fall moldboard plowing or delaying moldboard plowing until the next spring, reduced runoff by approximately 10%. Chisel plowing, which loosens the soil without inverting it and leaves a large amount of residues on the surface, provided by far the greatest benefit in reducing runoff (20% reduction over fall moldboard plowing). Soil loss from fall moldboard plowing on the 11% slope under fallow was 2.8 and 2.6 times greater than from spring moldboard plowing and fall chisel plowing, respectively. The majority of the difference in soil loss occurred during the summer months. The benefit of spring moldboard and fall chisel plowing was considerably less on the 8% slope in which soil loss from the fall moldboard plowing was only 24 and 19% higher than spring moldboard and fall chisel plowing, respectively, indicating that the benefits are slope dependent and increase with increasing slope from 8 to 11%. When the plots were planted in Chapais barley (Hordeum vulgare L.), soil losses were negligible. Tillage treatments, and particularly cropping practices, play a major role in seasonal distribution of runoff and soil loss. Under fallow, approximately 79% of runoff and 8.1% of soil loss occurred during the non-cropping season whereas 96% of runoff and 68% of soil loss were found when the plots were planted in barley. The soil erodibility factor was two to three times higher during March and April, which coincide with the winter-spring thaw period, than during the rest of the year. This seasonal variation must be considered when using event-based models to predict soil losses. Key words: Moldboard plow, chisel plow, subsoiling, erodibility, erosivity, universal soil loss equation, crop residue
Wood/sludge ash effects on white spruce seedling growth
Authors: Staples T E , Van Rees K. C. J.
Published: April 2011

The disposal of wood ash and/or pulp and paper mill sludges is becoming increasingly more challenging as landfills are more difficult to site due to diminishing land availability and public opposition, as well as more costly to construct and operate because of increasingly stringent regulations. The most notable alternative to disposal that is receiving the attention of the forest industry is land application. The objective of this study, therefore, was to determine the influence of applying a pulp mill wood/sludge ash mixture on 1) various soil chemical properties of an Orthic Gray Luvisol and 2) the growth and nutrient uptake of white spruce [Picea glauca (Moench) Voss] seedlings. The pulp mill wood/sludge ash mixture from an olivine burner was surface broadcast at rates of 1 and 5 Mg ha-1 around white spruce seedlings planted on disc-trenched microsites. Soil solutions from lysimeters and soil samples were analyzed for exchangeable elements, soil pH and electrical conductivity while white spruce tissue samples were analyzed for various elements. Applications of pulp mill wood/sludge ash material significantly increased the soil pH from 4.8 to 6.9, resulting in increased soil extractable and soil solution P, Ca, and Mg. Soil electrical conductivity (EC) was increased from about 0.02 dS m-1 to approximately 0.10 dS m-1 by the heavier application rate of ash. In addition, at higher ash application rates, white spruce seedling growth was significantly decreased, suggesting salt phytotoxicity effects from the ash. These results indicate that with proper rate determination and management of salt effects, land application of this material would not appear to pose serious problems for white spruce seedling establishment. Key words: Picea glauca, wood/sludge ash, Luvisols, lysimeters, electrical conductivity, pH
Combined primary/secondary papermill sludge as a nitrogen source in a cabbage-sweet corn cropping sequence
Authors: Simard R R
Published: April 2011

Combined primary/secondary papermill sludge (PS) is rich in N and may potentially be used as a N source for horticultural crops. A 3-yr experiment was conducted to determine the effects of PS application on crop yields, N uptake and N recovery. The PS was applied in 1996 on a Bedford silty clay (Humic Gleysol) cropped to winter cabbage (Brassica oleracea var capitata L. 'Bartolo') at 0, 8, 16, 32, and 64 Mg ha-1 (dry basis). In 1997, PS was applied at 44% of the 1996 rates to the same plots and cropped to sweet corn (Zea mays L. 'Delectable'). No PS was applied in 1998 to evaluate residual effects on corn. Treatments with ammonium nitrate (AN) at 50, 100 and 200% of N fertiliser recommendations were included each year as a reference for crop response. The PS had a C:N ratio of 42:1 in 1996 and of 28:1 in 1997. About 29% of the total N in PS was inorganic. Cabbage and corn marketable yields and N uptake increased with increasing amounts of PS applied. AN supplemented with PS further increased cabbage yields. Based on the N fertiliser replacement value, the N efficiency coefficient of PS was 44% in the first year. A N residual effect of the PS applied in 1996 was observed on the corn yield in 1997. The two PS applications also had a very significant residual effect on corn yield in the third year, although supplemental AN at 150 kg N ha-1 tended to further increase yields. The apparent total N recovery by the three crops was similar for PS and AN (i.e., 34 vs. 38%). The apparent recovery of organic N from PS decreased with increasing rates of application from 46 to 25%. These results suggest that PS is an effective source of N for crops and that significant residual N effects should be considered when estimating the N needs of subsequent crops. Key words: Cabbage, nitrogen, mineralization coefficient, paper mill residues, sweet corn
Carbon transformations by indigenous microbes in four hydrocarbon-contaminated soils under static remediation conditions
Authors: Bailey V L , McGill W B
Published: April 2011

We sought to learn about the transformations of hydrocarbons and limitations to bioremediation in four hydrocarbon-contaminated soils. Two soils were contaminated with creosote and two with petroleum. We incubated them either with or without added N, P, K and S. We monitored CO2 evolution, and residual dichloromethane-extractable organic C (DEO-C) after 10 wk. Indigenous populations were active in all soils. A single-component first-order model fit the CO2 respiration rate data, yielding estimates of potentially mineralizable C (Co), and specific decay rate, k. The ratio C: DEO was lower in heavier textured and strongly aggregated soils compared with the more poorly aggregated sandy soils. Low respiration rates in the more clayey soils were related to low Co rather than to k for the available C. In the highly amended soils the loss of total C approximated the production of CO2-C while the loss of DEO-C was greater than the evolution of CO2-C. We conclude: 1) Under circumstances such as hydrocarbon contaminants with long exposure to the soil, static systems may be sufficient for metabolism of available contaminants by indigenous microorganisms. 2) Increases in clay content and stability of aggregates, together with biotreatment to remove hydrocarbons may reduce bioavailability of residual contamination. 3) In soils with high clay content, contaminant transformations or attenuation without production of CO2 may be substantial. Key words: Bioremediation, bioaugmentation, soil, hydrocarbons, contaminant, kinetic models, bioavailability, respiration
The in situ analysis of organic matter in soils
Authors: Schnitzer Morris
Published: April 2011

Traditionally, studies on soil organic matter (SOM) begin with the extraction of SOM from soils, its fractionation into humic acid, fulvic acid, and humin, followed by de-ashing of each fraction. These are tedious, laborious and inefficient procedures that do not provide any chemical information on these materials. Instead, recently developed methods such as solid-state 13C NMR and pyrolysis – field ionization mass spectrometry (Py-FIMS) can now be used for the in situ analysis of SOM in soils. These methods identify the major chemical components of SOM without extractions and fractionations, and yield valuable information on the main chemical structures in these materials. A better knowledge of the structural chemistry of SOM will help SOM chemists and other soil scientists to better understand the complex chemical and biochemical reactions that occur in soils, and will enable them to develop practices that will improve soil management and soil productivity. Key words: Extraction, fractionation, solid state 13C NMR, pyrolysis-field ionization mass spectrometry, chemical composition
N2 fixation by soybeans grown with different levels of mineral nitrogen, and the fertilizer replacement value for a following crop
Authors: Goss M. J. , de Varennes A. , Smith P. S. , Ferguson J. A.
Published: April 2011

A field experiment was established to study the impact of added mineral N on the prediction of N2 fixation by soybean, and the consequences for the nature of any N credit that might be used to modify fertilizer recommendations to a following non-fixing crop. Nodulating and non-nodulating isolin es of soybean were grown with five rates of N fertilizer, and in a second year corn was grown in the same plots and its yield compared with a response curve. Yield, total N content, amount of N derived from soil, and fertilizer utilization of the nodulating isoline of soybean were not affected by fertilizer N. In contrast, mineral N inhibited nodulation and led to a decrease in the amount of N fixed. The balance of N in the soil was more negative for lower levels of applied N, but by the following spring the amount of mineral N in the soil was the same in all plots. The yield of corn was greater in the plots that had grown nodulating soybean than the non-nodulating isoline. The N fertilizer replacement value of 25 (8 kg N ha-1 resulted from a greater amount of root residues in the nodulating soybean, together with a C:N ratio that would favour faster mineralization than in the non-nodulating isoline. Key words: Corn, mineral N, N credit, fixation, soybean
Three approaches to define the ecotoxicity threshold for atmospheric ammonia
Authors: Sheppard S. C.
Published: April 2011

Atmospheric NH3 is potentially toxic to terrestrial plants, and there are other environmental effects such as haze from (NH4)2SO4 aerosols and N enrichment of ecosystems that are normally very low in N. Toxic levels can arise from atmospheric releases from livestock operations. Plants detoxify NH3 by incorporation of the N into the plant, so direct toxic effects are most likely when plants are growing slowly, as in cold weather. Indirect effects include leaching of nitrates and cations, and cation imbalances, and are most likely in N-poor, non-agronomic settings. The concentrations in air that cause direct toxic effects were summarized, and the corresponding "expected no effect value" (ENEV) was established at 35 nmol NH3 mol-1(48 µg m-3). Critical loads, the threshold flux density of NHx-N to the landscape that causes detrimental effects, were also summarized. The critical load was 10 kg N ha-1 yr-1. Using deposition velocity values from the literature (0.3 to 3.6 cm s-1), the ENEV implies a load flux of 24 to 290 kg N ha-1 yr-1. This is above the critical load, suggesting that critical loads to the landscape are more limiting than are direct toxic effects on plants. Another novel approach was to define an ENEV as the mean compensation point (ENEVcp). Compensation point is the atmospheric concentration below which plants emit NH3 and above which they absorb NH3. Compensation point data were summarized and the ENEVcp was established at 3.7 nmol mol-1 (5.1 µg m-3). This coincides with a load flux of 4.8 to 58 kg N ha-1 yr-1, more consistent with the critical loads. Key words: Priority Substance List, compensation point, ammonia toxicity, atmospheric ammonia
Characterizing soil biota in Canadian agroecosystems: State of knowledge in relation to soil organic matter
Authors: Fox C. A.
Published: April 2011

Organic residues resulting from crop and animal production either become incorporated in the soil or remain on the surface and, thus, provide much of the nutrient and energy sources for many soil organisms. Characterizing the response of soil biota to these organic materials is a challenging undertaking due to the complexity of the soil ecosystem with respect to the magnitude of biodiversity involved, the possibilities for interrelationships with biochemical and biophysical processes, and the immense range of scale of observation from particle, through to aggregate, field, landscape and regional levels. The objectives of this paper were to review the available research pertaining to Canadian agroecosystems, which characterize the response of soil biota to soil organic matter dynamics, and to identify the issues, challenges and knowledge gaps. The response by soil organisms is discussed from two approaches: (1) their state of occurrence in terms of population response to soil organic matter as a nutrient and carbon/energy source, and (2) the extent of their influence in contributing to organic matter dynamics, that is, assessing their functional role. For the most part, Canadian research has emphasized comparative studies based on population responses by broad soil biota groups to soil organic matter additions or losses as an outcome of undertaking various agronomic practices. Studies that evaluate the extent of contributions by soil biota to soil organic matter dynamics are few, and rare at the species level. For Canadian agroecosystems, there is currently a great need for research initiatives that address the immense knowledge gaps that exist in relation to (a) identifying the specific contributions to soil organic matter processes and interactions of soil biota both at species and community level, (b) predicting outcomes of the contributions of soil biota groups in regulating or controlling soil organic matter processes both spatially and temporally across landscapes, and (c) assessing the risk to soil biodiversity in various agroecosystems in being able to sustain these functional roles. Key words: Soil biota, functional role, soil organic matter, agroecosystems, ecosystem services
Nematode biodiversity in Canadian agricultural soils
Authors: Potter J. W. , McKeown A. W.
Published: April 2011

The biodiversity of soil-inhabiting nematodes in Canada is incompletely known, as large areas of Canada’s landmass have not been surveyed for nematode fauna. Nematodes considered as indigenous are generally well adapted to a variety of ecological niches and climatic zones. Much of the available information is based on agricultural ecosystems and agricultural species, and thus is biased toward conditions in disturbed ecosystems and away from “primeval” ecology. Introduced nematode species are frequently quite pathogenic, even to exotic host plants from the same geographic point of origin. Estimates of crop loss due to single species infestations of pathogenic nematodes and the costs of nematode control using chemicals are reasonably well known, averaging about 10% of crop value, but ranging to 100% depending on the situation; the cost of damage by multiple-species infestations is less defined. Nematode-suppressive mechanisms are understood in only a few plant species; sulfur appears to be important as a constituent of active compounds in suppressive plants of agricultural origin. Similarly, some native plants are equally adapted with allelopathic chemicals that suppress nematodes. Management of nematode populations in agricultural soils by integrated crop management methods is at an early stage, requiring research to quantify effects of nematode-suppressive plants and soil amendments containing nitrogen. An integrated program could include nematode-suppressive plants, appropriate soil amendments, and the promotion of microbial antagonists. Different mathematical methods may be required to analyze and explain multi-factor nematode control systems. Less-toxic management systems could benefit the soil-inhabiting nematodes that predate arthropod soil pests. Further research on soil-borne nematodes may demonstrate the value of nematodes as indicators of agroecosystem health and environmental pollutants. Key words: Biocontrol, biodiversity, nematode distribution, nematode management, soil ecology
Fungal plant pathogens and soil biodiversity
Authors: Reeleder R. D.
Published: April 2011

The role of biodiversity as it affects the control of soil-borne fungal pathogens is discussed. Soil-borne fungal plant pathogens have often proven difficult to manage with conventional methods of disease control. Nonetheless, researchers have characterized several naturally occurring “disease-suppressive” soils where crop loss from disease is less than would otherwise be expected. Suppressive soils can also result from the incorporation of various amendments into soil. In most cases, disease control in such soils has been shown to be biological in nature; that is, soil organisms appear to directly or indirectly inhibit the development of disease. Increased knowledge of the identity and functioning of these organisms may support the development of techniques that can be used to develop suppressiveness in soils that are otherwise disease-conducive. Populations of pathogens themselves have been shown to exhibit considerable genetic diversity; the ability of populations to respond to disease control measures should be considered when developing a management strategy. New molecular techniques can be exploited to better characterize soil communities, including the pathogens themselves, as well as community responses to various disease control options. The contributions of Canadian researchers to these areas are discussed and models for further study are proposed. Key words: Biocontrol, molecular technologies, functional diversity, integrated pest management
Evaluation of carbon and nitrogen mineralization rates in meadow soils from dairy farms under transit to biological cropping systems
Authors: Sibih M. , N’Dayegamiye A. , Karam A.
Published: April 2011

Mineralized soil N from meadow soils will become an important source of N to following crops in low-input biological cropping systems. The C and N mineralization rates of soils from 34 sites situated on dairy farms recently converted to biological cropping systems were evaluated in a 56-wk incubation at 25° C. Data on C and N mineralization were fitted to first-order kinetic models. Carbon and N generally presented similar patterns of mineralization. Total mineralized N (Nm) ranged between 88 and 235 mg N kg-1 soil, which represented 6.6 to 22% of total N. Carbon mineralization (Cm) rate was between 11 and 17 times greater than N mineralization (1523–2638 mg C kg-1 soil ) and C mineralized represented 9 to 19% of soil organic C. The rate constant was between 0.05 and 0.123 wk-1 for C (kC) and ranged from 0.032 to 0.088 wk-1 for N (kN). The half-life for C (TC0) and for N (TN0) varied, respectively, between 5.6 and 13.3 wk and between 15 and 28 wk. Results show that about 80% of total mineralized C and N were mineralized during the first 25 wk of incubation, corresponding to the mineralizable fraction of soil organic matter (OM). Data on C and N mineralization have been adjusted using a bicompartmental model (active and recalcitrant pools), which corresponded, respectively, to first-order and exponential equations. Total mineralizable C and N (Cm and Nm), and the C and N rate constants (kC and kN) were strongly related, whereas the rate constants of the recalcitrant pools (hc and hN) were negatively related to these parameters. This suggests that C and N mineralizable pools were independent of the humified stable OM (recalcitrant pool). Carbon and N mineralization parameters were positively related to the soil clay and silt contents, but inversely to the sand levels. This study indicates that when ploughed, meadow soils contain large mineralizable N pools, which could sustain following crops with N nutrition in low-input biological cropping systems. Key words: Meadow soils, C and N mineralization rates, low-input systems, dairy farms, soil particles sizes
Short-term impact of fallow frequency and perennial grass on soil organic carbon in a Brown Chernozem in southern Alberta
Authors: Bremer E. , Janzen H H , McKenzie R H
Published: April 2011

Maximum sequestration of atmospheric C in agricultural soils of the Canadian prairies can be achieved by the replacement of crop rotations that include summer fallow with continuous cropping or perennial forages. However, few studies have documented potential gains of soil organic C (SOC) in the region with the greatest use of fallow, the Brown soil zone. A dryland crop rotation study was initiated in 1992 on a Chin clay loam (Orthic Brown Chernozem) in southeastern Alberta on a site that had previously been under conventional irrigated cereal production. The study included fertilized and unfertilized treatments of the following crop rotations: fallow-wheat (FW), fallow-wheat-wheat (FWW), continuous wheat (W) and grass (G). The grass rotation consisted of pubescent wheatgrass (Agropyron trichophorum) harvested for hay. Total organic-, light fraction- and 10-wk mineralized-C and -N were determined in fall 1997, 6 yr after study initiation. Growing season precipitation (April through August) was 43% above long-term normals in the first 2 yr of this study, supporting excellent grass establishment and high crop yields, but was below normal thereafter. Fertilization with N and P increased average rotation yields by 21 to 56%, with the greatest yield increases in the G and W rotations. Total SOC to 15 cm (equivalent mass basis) was 1.5 Mg ha-1 higher (P = 0.03) in the W rotation and 3.0 Mg ha-1 higher (P = 0.0001) in the G rotation than in the FW rotation, but was not affected by fertilizer treatment or the interaction of fertilizer and crop rotation treatments. Low variability in measured SOC allowed us to detect differences as low as 1.3 Mg ha-1 among crop rotations, demonstrating that small effects of crop management on SOC can be detected using appropriate methods at uniform sites. Much of the gain in SOC in the G treatment was in mineralizable and light fraction material, indicating that this gain in SOC would be readily lost upon reversion to annual cropping. A simple calculation of residue C inputs and conversion to SOC showed that most of the gain in SOC in the W treatment was due to increased crop residue inputs, but that both increased inputs and reduced decomposition rates likely affected SOC gains in the G treatment. The average gain in SOC during the 6-yr period of this study was 0.25 Mg ha-1 yr-1 due to the elimination of fallow and 0.5 Mg ha-1 yr-1 due to establishment of a perennial forage. Key words: Soil organic matter, carbon sequestration, summer fallow, light fraction
Influence of composts and liquid pig manure on CO2 and N2O emissions from a clay loam soil
Authors: Yang X M , Drury C F , Reynolds W D , McKenney D J , Tan C S , Zhang T Q , Fleming R J
Published: April 2011

Application of raw animal manure to agricultural land has resulted in environmental and health problems. Alternatives, such as composting, are now being developed to alleviate this situation. However, very little information is available regarding the fate of composts when added to fine-textured and poorly drained soils, especially with respect to the initial decomposition of composts and their effects on soil-derived CO2 and N2O emissions. We evaluated food waste compost (FW), yard waste compost (YW), liquid pig manure (LPM), LPM + yard waste compost (PMY) and LPM + wheat straw compost (PMS). Red clover (Trifolium pratense L.) (RC) and an unamended control soil were also tested. The solid amendments were divided into ground and unground treatments. Carbon dioxide emissions were increased relative to the control soil for all treatments except PMY. Total CO2 emissions over the 144-h incubation from unground material followed the pattern (P < 0.05): YW (849 mg CO2-C kg-1 soil) > RC (554 mg CO2-C kg-1 soil) > LPM (444 mg CO2-C kg-1 soil) > FW (203 mg CO2-C kg-1 soil) ≈ PMS (194 mg CO2-C kg-1 soil) ≈ PMY (157 mg CO2-C kg-1 soil). The RC, YW and PMS significantly increased N2O emissions compared to all other treatments and the control. Total N2O emissions from unground material over the 144-h incubation followed the pattern (P < 0.05): RC ≈ YW ≈ PMS (1230–1490 μg N2O-N kg-1 soil) > LPM ≈ FW ≈ PMY ≈ Control (44-404 μg N2O-N kg-1 soil). Grinding was found to increase CO2 emissions from YW, PMY, PMS, and N2O emissions from RC. The CO2 emissions were due primarily to amendment composition and not particle size, as the relative differences in CO2 emission among ground and unground treatments remained nearly constant. Carbon dioxide emissions from LPM were reduced substantially by composting the manure with yard waste (PMY). Key words: Compost, pig manure, carbon dioxide, nitrous dioxide, available N, incubation
Quantification of soil redistribution and sediment budget in a Canadian watershed from fallout caesium-137 (137Cs) data
Authors: Mabit L. , Bernard C. , Laverdière M R
Published: April 2011

The intensification and specialization of agriculture that took place in the past decades have resulted in soil and water degradation in several areas of eastern Canada. Most studies on soil erosion in Quebec have been conducted at the experimental plot scale. Although this approach generates precise data, extrapolation at the field or watershed scale is difficult. In this study, caesium-137 (137Cs) was used to investigate the spatial extent and severity of soil erosion for an 80-ha watershed in Southeastern Quebec (cultivated area = 75 ha). Soil samples were collected based on a 25 (30 m grid and revealed soil redistribution rates ranging from -20 to +12 Mg ha-1 yr-1. From radiocaesium measurements, it was estimated that the experimental watershed experienced an average loss of 3.0 Mg ha-1 yr-1 with net sediment export of 2.8 Mg ha-1 yr-1 and a sediment delivery ratio of 93%. Snowmelt erosion is believed to have played an important role in the soil redistribution in this small watershed. Changing sampling strategy was tested (50 x 60 m and 100 x 120 m grid rather than 25 x 30 m) and only minor changes were noticed on soil erosion and sediment production estimates, when samples corresponding to the 50 x 60 m grid were used. Key words: Caesium-137 (137Cs), watershed, water erosion, snowmelt erosion, sampling strategy
Phosphorus concentrations in subsurface water as influenced by cropping systems and fertilizer sources
Authors: Carefoot J. P. , Whalen J. K.
Published: April 2011

Over-fertilization of agricultural soils with P has been linked to water pollution, and it is becoming apparent that subsurface P losses can be substantial. The silty-loam Gleysol chosen for this study contained 146 mg Mehlich-3 P kg-1, which exceeds the critical limit (66 mg Mehlich-3 P kg-1) for Québec. Equal quantities of fertilizer P (45 kg P ha-1) were applied from inorganic (triple superphosphate) and organic (composted cattle manure) sources to corn-corn and corn-soybean rotations. We evaluated crop production, the Mehlich-3 P and degree of soil P saturation levels, and the P concentration in subsurface water. Crop yields were unaffected by the fertilizer source, and only 31 to 67% of the P applied over a 2-yr period was exported, suggesting that the P fertilizer rate, chosen to match the P requirements of the corn crop, was excessive. After 2 yr, surface (0 to 15 cm) soils contained 149 to 199 mg Mehlich-3 P kg-1 and the Mehlich-3 (P/Al) saturation ratio (DSPSM3) ranged from 0.10 to 0.14. Subsurface water from piezometers installed to a 60-cm depth contained between 0.3 and 1.7 mg total P L-1, and particulate P was the dominant P form at most sampling dates. Mehlich-3 P was positively correlated with dissolved reactive P, whereas the DSPSM3 was positively correlated with the total P and particulate P concentrations in subsurface water. We conclude that these soil test parameters could be useful indicators of subsurface P losses from Québec soils. Key words: Soil test P, degree of soil P saturation, composted cattle manure, triple superphosphate, P leaching
Effect of rate, frequency and incorporation of feedlot cattle manure on soil nitrogen availability, crop performance and nitrogen use efficiency in east-central Saskatchewan
Authors: Mooleki S. P. , Schoenau J. J. , Charles J. L. , Wen G.
Published: April 2011

A study was initiated in 1996 in the Black Soil zone in east-central Saskatchewan to examine soil and crop response to application of feedlot cattle manure at different application rates, frequencies and incorporation timing in a sandy loam and loam soil. Three rates of feedlot cattle manure (approx. 100, 200 and 400 kg total N ha-1) were applied annually and under reduced frequency application regimes. Canola (Brassica napus, L.), spring wheat (Triticum aestivum, L.), hulless barley (Hordeum vulgare, L.) and canola were seeded in spring of 1997, 1998, 1999 and 2000, respectively. Pre-seeding available N (0–60 cm) increased with application rates. Annual application resulted in a linear increase in grain yield with application rates but had no effect on grain N concentration. Cumulative N use efficiency was low (7–10%) with no significant difference among treatments. Single application showed significant residual fertility benefit in the second year but not in the third year except at the high rate. Incorporation timing of feedlot cattle manure had no impact on soil or crop performance. Low availability of N in feedlot cattle manure over the short-term suggests the need for high application rates or addition of supplemental N fertilizer in order to meet crop N requirements. Key words: Feedlot cattle manure, N availability, manure management, N use efficiency
Interactive effects of composts and liquid pig manure with added nitrate on soil carbon dioxide and nitrous oxide emissions from soil under aerobic and anaerobic conditions
Authors: Yang X. M. , Drury C. F. , Reynolds W. D. , Tan C. S. , McKenney D. J.
Published: April 2011

The composting process results in immobilization of inorganic N. When high-Ndemanding crops are grown in compost- amended soils, additional N fertilizer is often applied. The combination of elevated nitrate levels from N fertilizer and high C inputs from the compost may result in enhanced greenhouse gas emissions. Hence, the objective of this laboratory incubation study was to characterize CO2 and N2O emissions from a Brookston clay loam soil that has received organic amendments in the presence or absence of added nitrate. The organic amendments included urban yard waste compost (YWC), liquid pig manure + wheat straw compost (PMC), and liquid pig manure (LPM). The nitrate treatments included added nitrate (100 mg KNO3-N kg soil-1) or no added nitrate. Total CO2 emissions during aerobic incubation followed the pattern: YWC > LPM > PMC > control (no organic amendments) for both nitrate treatments. Nitrate addition increased CO2 emissions from the YWC- and LPM-amended soils by 9 and 43%, respectively, but had no significant effect (P < 0.05) on CO2 emissions from the control or the PMC-amended soil. All organic amendments increased N2O emissions compared to the control. When nitrate was added to aerobically incubated LPM-amended soils, N2O emissions were increased over seven times; however, N2O emissions were decreased by 93% for PMC-amended soils and by 50% for YWC-amended soils. These decreases in N2O production occurred when nitrate was added to the YWC and PMC treatments under aerobic conditions but not under anaerobic conditions. Composted liquid pig manure was found to be more environmentally friendly than raw liquid pig manure as it stabilized the manure C and reduced CO2 and N2O emissions compared to the liquid pig manure. Key words: Compost, liquid pig manure, carbon dioxide, nitrous oxide, denitrification
Papermill biosolid and hog manure compost affect short-term biological activity and crop yield of a sandy soil
Authors: Lalande R. , Gagnon B. , Simard R. R.
Published: April 2011

Soils used for intensive vegetable production often become depleted in their organic matter content, and consequently low in their microbial activity. Papermill sludge compost may be an efficient way to improve the biological activity of these soils. An experiment was initiated to determine the effects of a co-composted papermill sludge and hog manure (PHC), applied alone or in combination with mineral fertilizers (MF), on several biochemical properties and crop yield of a Bevin loamy sand (Orthic Humo-Ferric Podzol) located at Saint-Ubalde, province of Quebec, Canada. The PHC was applied in the spring of 1997 at rates of 0, 11.5, 23 and 34.5 Mg dry weight ha-1, with and without MF equivalent to 150 N-200 P2O5-200 K2O kg ha-1. Potatoes (Solanum tuberosum L.) were planted the first year and the residual effect of PHC was evaluated on a spring wheat (Triticum aestivum L.) crop in 1998. Enzymatic activity of β-glucosidase, β-galactosidase, acid phosphatase, urease and fluorescein diacetate hydrolysis, microbial biomass C (MBC) and CO2-C release in incubation were measured throughout both growing seasons. Application of 11.5 Mg ha-1 of PHC resulted in the highest enzymatic activities and MBC, representing a mean in crease of respectively 30 and 55% over the control. Addition of MF to PHC resulted in a greater increase in enzyme activities (12–18%) than PHC alone but had little effect on MBC. Generally, enzyme activities and MBC decreased in the second season. The carbon mineralization potential was low, indicating that the composted material was relatively stable. The addition of 11.5 Mg PHC ha-1 produced the highest marketable potato tuber yield with (34 Mg ha-1) or without (27 Mg ha-1) fertilizer supplement, whereas the highest wheat grain yield was obtained with the 23 Mg PHC ha-1 level in the following season. When PHC was added at 11.5 Mg ha-1, it markedly improved soil biochemical properties and potato crop yield whereas the 34.5 Mg ha-1 level was excessive. Key words: Papermill, farm manure, compost, enzyme activity, microbial biomass
Soil air sample storage and handling using polypropylene syringes and glass vials
Authors: Rochette Philippe , Bertrand Normand
Published: April 2011

Accurate determination of gas concentration in soil air samples implies adequate sampling and storage procedures to preserve sample integrity. In this study, we tested polypropylene syringes and glass vials for handling and storage of N2O air samples. Losses of N2O were large and rapid when a gas standard was stored in polypropylene syringes (16% after 24 h). Moreover, gas adsorption on the inner walls (and rubber gasket) of the syringes reached a maximum of 5.8% of the initial N2O after 7 h of storage. These results indicated that polypropylene syringes are not reliable for storing air samples. Commercially available glass vials maintained a moderately high level of vacuum over time (89% after 136 d). However, their overall performance was decreased by contamination (approx. 3%) occurring at the end of the evacuation procedure when the hole left by the needle of the evacuation line took a few seconds to close up. The addition of a silicone septum was proposed to reduce this contamination. The modified vials maintained an average vacuum level of 98% after 136 d. The average contamination rate of N2O samples during the first 129 d of storage was 0.20 and 0.13% d-1 with one and two septa, respectively. Key words: Nitrous oxide, air sample
Phosphorus amounts and distribution in a Saskatchewan soil after five years of swine and cattle manure application
Authors: Qian P. , Schoenau J. J. , Wu T. , Mooleki P.
Published: April 2011

Repeated application of animal manures to Saskatchewan soils has led to interest in the fate and distribution of residual manure P in the soil. The concentrations of soil phosphorus in various inorganic and organic fractions were investigated in soils sampled from long-term field research plots (Dixon, SK) with a 5-yr history of annual application of liquid swine manure or solid cattle manure at low, medium and high rates. The soil type at the research site is a loamy textured Black Chernozem (Cudworth Association). Annual rates of manure application over the 5 yr were based on the N contents in the manures and were equivalent to 0 (control), and approximately 100 (low), 200 (medium) and 400 (high) kg total N ha-1 yr-1 as manure. For comparison, urea alone was also applied at rates of 50, 100 and 200 kg N ha-1 yr-1. The total P concentration in the surface soil (0&ndash15 cm) was significantly increased only by the addition of cattle manure and only in the medium and high rate treatments compared to the control. The most labile P fractions (Resin-P and NaHCO3-P) were also significantly increased with increasing rate of cattle manure addition. No significant increases in either soil total P or labile P fractions were observed in liquid swine manure treatments, which is attributed to the lower amount of P added with the swine manure treatment than the cattle manure treatment. Added P in the swine manure treatment more closely matched P removal in crop harvest compared to cattle manure treatment, which had more P added than was removed by the crop. Key words: Phosphorus fractions, labile P fraction, sequential P extraction, urea, swine manure, cattle manure
Management effects on the dynamics and storage rates of organic matter in long-term crop rotations
Authors: Paul E. A. , Collins H. P. , Paustian K. , Elliott E. T. , Frey S. , Juma N. , Janzen H. , Campbell C. A. , Zentner R. P. , Lafond G. P. , Moulin A. P.
Published: April 2011

Factors controlling soil organic matter (SOM) dynamics in soil C sequestration and N fertility were determined from multi-site analysis of long-term, crop rotation experiments in Western Canada. Analyses included bulk density, organic and inorganic C and N, particulate organic C (POM-C) and N (POM -N), and CO2-C evolved during laboratory incubation. The POM-C and POM-N contents varied with soil type. Differences in POM-C contents between treatments at a site (δPOM-C) were related (r2= 0.68) to treatment differences in soil C (δSOC). The CO2-C, evolved during laboratory incubation, was the most sensitive indicator of management effects. The Gray Luvisol (Breton, AB) cultivated plots had a fivefold difference in CO2-C release relative to a twofold difference in soil organic carbon (SOC). Soils from cropped, Black Chernozems (Melfort and Indian Head, SK) and Dark Brown Chernozems (Lethbridge, AB) released 50 to 60% as much CO2-C as grassland soils. Differences in CO2 evolution from the treatment with the lowest SOM on a site and that of other treatments (δCO2-C) in the early stages of the incubation were correlated to δPOM-C and this pool reflects short-term SOC storage. Management for soil fertility, such as N release, may differ from management for C sequestration. Key words: Multi-site analysis, soil management, soil C and N, POM-C and N, CO2 evolution