• Authors:
    • Kebreab, E.
    • Gao, X. P.
    • Flaten, D. N.
    • Tenuta, M.
    • Asgedom, H.
  • Source: Web Of Knowledge
  • Volume: 106
  • Issue: 2
  • Year: 2014
  • Summary: Soil N 2O emissions vary with N source. A study was undertaken on a clay soil in the Red River Valley, Manitoba, Canada, to determine the effect of granular N fertilizers and dairy manure on N 2O emissions from a field cropped to rapeseed ( Brassica napus L.) in 2009 and spring wheat ( Triticum aestivum L.) in 2010. Treatments included an unamended control, granular urea, controlled-release urea (ESN), stabilized urea (SuperU), and solid dairy manure added at rates to achieve a total of 140 kg available N ha -1 (product plus soil N test). The N fertilizers were broadcast and shallowly incorporated each spring before planting; the manure was broadcast incorporated the previous fall. Nitrous oxide emissions were monitored from planting to freeze in fall and during spring thaw in 2011 using static-vented chambers. In both years, N 2O emissions occurred within 4 to 5 wk of planting but not in fall after manure application. Area-scale cumulative N 2O emissions (SigmaN 2O, kg N ha -1) from planting to freeze were control < ESN=manure < urea=SuperU. Nitrous oxide emission factors were 0.017 kg N 2O-N kg -1 available N added for urea and SuperU and 0.007 kg N 2O-N kg -1 available N for ESN. Seventy-eight percent of the variation in SigmaN 2O could be explained by NO 3- intensity, an integration of soil NO 3- concentrations during the study periods. Greater SigmaN 2O were also associated with higher yields. These findings suggest that N release rates, as indicated by NO 3- intensity and yield, determined N 2O emissions. The results highlight the challenge of meeting crop demand yet reducing N 2O emissions by selection of an N source.
  • Authors:
    • Nemeth, D. D.
    • Smith, J. M.
    • Congreves, K. A.
    • Hooker, D. C.
    • Eerd, L. L. van
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: Soil organic carbon (SOC) is crucial for maintaining a productive agro-ecosystem. Long-term research must be synthesized to understand the effects of land management on SOC storage and to develop best practices to prevent soil degradation. Therefore, this review compiled an inventory of long-term Ontario studies and assessed SOC storage under common Ontario land management regimes via a meta-analysis and literature review. In general, greater SOC storage occurred in no-till (NT) vs. tillage systems, in crop rotation vs. continuous corn, and in N fertilizer vs. no N fertilizer systems; however, soil texture and perhaps drainage class may determine the effects of tillage. The effect on SOC storage was variable when deeper soil depth ranges (0-45 cm) were considered for NT and rotational cropping, which suggests an unpredictable effect of land management on SOC at depths below the plough layer. Therefore, researchers are encouraged to use the presented inventory of nine long-term research sites and 18 active experiments in Ontario to pursue coordinated studies of long-term land management on SOC at depths extending below the plough layer.
  • Authors:
    • Yang, X. M.
    • McLaughlin, N. B.
    • Tan, C. S.
    • Reynolds, W. D.
    • Drury, C. F.
    • Calder, W.
    • Oloya, T. O.
    • Yang, J. Y.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: A field study was established in 1959 to evaluate the effects of fertilization and crop rotation on crop yields, soil and environmental quality on a Brookston clay loam. There were two fertilizer treatments (fertilized and not-fertilized) and six cropping treatments including continuous corn (CC), continuous Kentucky bluegrass sod and a 4-yr rotation of corn-oat-alfalfa-alfalfa with each phase present each year. We measured N 2O emissions, inorganic N and plant N uptake over three growing seasons (2007-2009) in the corn phase. Nitrous oxide emissions varied over the 3 yr as a result of the seasonal variation in precipitation quantity, intensity and timing and differences in crop growth and N uptake. Fertilized CC lost, on average, 7.36 kg N ha -1 by N 2O emissions, whereas the not-fertilized CC lost only 0.51 kg N ha -1. Fertilized rotation corn (RC) lost 6.46 kg N ha -1, which was 12% lower than fertilized CC. The not-fertilized RC, on the other hand, emitted about half as much N 2O (2.95 kg N ha -1) as the fertilized RC. Fertilized RC had corn grain yields that averaged 10.0 t ha -1 over the 3 yr followed by fertilized CC at 5.48 t ha -1. Not-fertilized RC corn had yields that were 61% lower (3.93 t ha -1) than fertilized RC, whereas the not-fertilized CC had yields that were 75% lower (1.39 t ha -1) than fertilized CC. Nitrous oxide emissions were found to be dramatically affected by long-term management practices and crop rotation had lower emissions in the corn phase of the rotation even though the N input from fertilizer addition and legume N fixation was greater. These N 2O emission and yield results were due to both factors that are traditionally used to describe these processes as well as long-term soil quality factors, which were created by the long-term management (i.e., soil organic carbon, soil physical parameters such as bulk density, and porosity, soil fauna and micro-flora) and that influenced crop growth, N uptake and soil water contents.
  • Authors:
    • Fleming, R.
    • McKenney, D. J.
    • Guo, X.
    • Tan, C. S.
    • Yang, X. M.
    • Reynolds, W. D.
    • Drury, C. F.
    • Denholme, K.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: The impacts of compost type on corn grain yields over 10 yr and N 2O and CO 2 emissions in the first 3 yr after compost application were evaluated on a Brookston clay loam soil in Woodslee, ON. The treatments included yard waste compost (YWC), kitchen food waste compost (FWC), and pig manure compost (PMC), which were applied once in the fall of 1998 to field plots at a rate of 75 Mg ha -1 (dry weight basis) and no further applications occurred thereafter as well as a fertilized control treatment. Large application rates were examined to see if the various compost sources could have a lasting effect on soil C storage, N 2O and CO 2 emissions and corn yields. Compost application significantly increased corn grain yields by 12.9 to 19.4% over 3 yr. However, after 10 yr, FWC was the only compost source which significantly increased yields by 11.3% compared with the fertilized control. Emissions of N 2O and CO 2 varied with compost type, soil water content and time. Greater N 2O emissions occurred in 1999 from PMC (5.4 kg N ha -1) than YWC (2.7 kg N ha -1) and FWC (1.3 kg N ha -1); however, the N 2O emissions from the PMC were less than from YWC and FWC in 2001. The 3-yr average N 2O emissions were significantly greater with PMC (2.7 kg N ha -1) and YWC (2.5 kg N ha -1) compared with the control (1.5 kg N ha -1). Hence, the timing of N 2O emissions varied by compost type, but the overall losses were similar as the higher N 2O losses in the first year with PMC were offset by the reduced losses with PMC in the third year. Significantly more CO 2 was produced from the FWC in 2000 and from PMC in 2001 than the control.
  • Authors:
    • Verhallen, A.
    • Hayes, A.
    • Congreves, K. A.
    • Eerd, L. L. van
    • Hooker, D. C.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: Long-term studies allow for quantification of the effects of crop production practices, such as tillage and crop rotation, on soil quality and soil C and N stores. In two experiments at Ridgetown, ON, we evaluated the long-term (11 and 15 yr) effect of tillage system and crop rotation on soil quality via the Cornell Soil Health Assessment (CSHA) at 0-15 cm and soil organic C (SOC) and total N at 5-, 10-, and 20-cm increments to 120 cm depth. The CSHA soil quality score and SOC and total N were higher with no-till (NT) than fall moldboard plough with spring cultivation (conventional tillage, CT) and rotations with winter wheat [soybean-winter wheat (S-W) and soybean-winter wheat-corn (S-W-C)] compared with rotations without winter wheat. In both long-term trials, NT had ca. 21 Mg ha -1 more or 14% higher SOC than CT in the 0- to 100-cm soil profile, a trend which contrasts previous research in eastern Canada. Thus, the two long-term trial results at Ridgetown suggest that to improve soil quality and storage of C and N, growers on clay loam soil in southwestern Ontario should consider adopting NT production practices and including winter wheat in the rotation.
  • Authors:
    • Puurveen, D.
    • Malhi, S. S.
    • Dyck, M. F.
    • Giweta, M.
    • Robertson, J. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: We analyzed the change in total soil organic carbon (SOC) in a long-term fertilization experiment (1980-2008) in a wheat-oat-barley-hay-hay rotation system at the University of Alberta Breton Classical plots. Soil samples were taken in 1980, 1990, 1998, 2003 and 2008 from plots that were fertilized with NPKS and NPK. The objective was to compare the relative effect of S fertilization on the SOC stocks in a S-deficient soil. Long-term S fertilization resulted in an increasing trend in soil organic carbon concentrations over 28 yr when N, P and K supply were adequate. The change in SOC with time was significantly different ( P<0.05) between the two treatments. Annual application of NPK in combination with S resulted in an increased accumulation of SOC at a rate of 0.11 Mg C ha -1 yr -1 in the 0- to 15-cm depth over NPK alone. Our results suggest that long-term S fertilization in an S-deficient soil helped to sequester C in the soil.
  • Authors:
    • Grant, C. A.
    • Burton, D. L.
    • Miller, J. J.
    • Zebarth, B. J.
    • Sharifi, M.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 99
  • Issue: 1-3
  • Year: 2014
  • Summary: Long-term effects of fresh (FM) versus composted (CM) beef manure application to barley (Hordeum vulgare L.) on potentially mineralizable nitrogen (N (0) ), and mineralizable nitrogen (N) pools, were evaluated in a clay loam soil in southern Alberta, Canada. A suite of laboratory-based indices were evaluated for prediction of soil N supply. The treatments were three rates (13, 39, 77 Mg ha(-1) dry wt.) of FM or CM containing either straw or wood-chip bedding, 100 kg N ha(-1) as inorganic fertilizer, and an unfertilized control. Treatments were fall-applied annually for 8 years (1998-2005). Soil samples (top 15 cm) were collected in spring 2006. The medium and high rates of organic amendment resulted in increases in N (0) , and readily (Pool I) and intermediate (Pool II) mineralizable N pools in ranges of 140-355 % compared with the average of the fertilizer and control treatments. Fertilizer application had no significant effect on mineralizable N pools, but increased the mineralization rate constant (k) compared with the control. Application of FM and use of straw bedding resulted in a greater quantity of readily available and intermediate mineralizable N, and also increased the rate of N turn-over as indicated by greater values of k, compared with CM and wood-chip bedding. Among laboratory-based measures of soil N supply, CaCl2-NO3 (r(2) = 0.84) and NaHCO3-205 (r (2) = 0.79) were strong predictors of plant N uptake (PNU). Increased soil mineralizable N did not translate into greater barley dry-matter yield or PNU. Composted beef manure and use of wood-chip bedding can be recommended as alternatives to FM and use of straw bedding for barley production is Southern Alberta.
  • Authors:
    • Angers, D. A.
    • Gregorich, E. G.
    • Barker, J.
    • Grayston, S. J.
    • Feng, X. J.
    • Clemente, J. S.
    • Simpson, M. J.
    • Yanni, S. F.
    • Poirier, V.
    • Gul, S.
    • Whalen, J. K.
    • Rochette, P.
    • Janzen, H. H.
  • Source: Canadian Journal of Plant Science
  • Volume: 94
  • Issue: 6
  • Year: 2014
  • Summary: Plants figure prominently in efforts to promote C sequestration in agricultural soils, and to mitigate greenhouse gas (GHG) emissions. The objective of the project was to measure the transformations of plant carbon in soil through controlled laboratory experiments, to further understand (1) root-associated CO 2 and N 2O production during a plant's life cycle, (2) decomposition of plant residues leading to CO 2 production, and (3) stabilization and retention of undecomposed plant residues and microbial by-products in the resistant soil C fraction. Experimental plant materials included transgenic near isolines of Zea mays L. and cell wall mutants of Arabidopsis thaliana, selected for their diverse residue chemistry. Phenology, morphology and above-ground biomass affected soil respiration and N 2O production in root-associated soils. Mineralization of C and N from incubated plant-soil mixtures was complemented with stable isotope tracing ( 13C, 15N) and 13C-phospholipid fatty acid analysis. Advanced chemical techniques such as nuclear magnetic resonance spectroscopy and physical separation (particle size and density separation) were used to track the transformations of plant C into stable soil C compounds. Conceptual models were proposed to explain how the plant residue chemistry * soil physico-chemical interaction affects C sequestration. Incorporating single gene mutations affecting lignin biosynthesis into agricultural and bioenergy crops has the potential to alter short- and long-term C cycling in agroecosystems.
  • Authors:
    • Campbell, C. A.
    • Lemke, R. L.
    • Chai, Q.
    • Liang, C.
    • Gan, Y. T.
    • Zentner, R. P.
  • Source: NATURE COMMUNICATIONS
  • Volume: 5
  • Year: 2014
  • Summary: Wheat is one of the world's most favoured food sources, reaching millions of people on a daily basis. However, its production has climatic consequences. Fuel, inorganic fertilizers and pesticides used in wheat production emit greenhouse gases that can contribute negatively to climate change. It is unknown whether adopting alternative farming practices will increase crop yield while reducing carbon emissions. Here we quantify the carbon footprint of alternative wheat production systems suited to semiarid environments. We find that integrating improved farming practices (that is, fertilizing crops based on soil tests, reducing summerfallow frequencies and rotating cereals with grain legumes) lowers wheat carbon footprint effectively, averaging -256 kg CO2 eq ha(-1) per year. For each kg of wheat grain produced, a net 0.027-0.377 kg CO2 eq is sequestered into the soil. With the suite of improved farming practices, wheat takes up more CO2 from the atmosphere than is actually emitted during its production.
  • Authors:
    • Sharma, M.
    • Luckai, N.
    • Shahi, C.
    • Homagain, K.
  • Source: JOURNAL OF FORESTRY RESEARCH
  • Volume: 25
  • Issue: 4
  • Year: 2014
  • Summary: Biochar is normally produced as a by-product of bioenergy. However, if biochar is produced as a co-product with bioenergy from sustainably managed forests and used for soil amendment, it could provide a carbon neutral or even carbon negative solution for current environmental degradation problems. In this paper, we present a comprehensive review of biochar production as a co-product of bioenergy and its implications. We focus on biochar production with reference to biomass availability and sustainability and on biochar utilization for its soil amendment and greenhouse gas emissions reduction properties. Past studies confirm that northwestern Ontario has a sustainable and sufficient supply of biomass feedstock that can be used to produce bioenergy, with biochar as a co-product that can replace fossil fuel consumption, increase soil productivity and sequester carbon in the long run. For the next step, we recommend that comprehensive life cycle assessment of biochar-based bioenergy production, from raw material collection to biochar application, with an extensive economic assessment is necessary for making this technology commercially viable in northwestern Ontario.