• Authors:
    • Alluvione, F.
    • Del Grosso, S. J.
    • Halvorson, A. D.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 2
  • Year: 2010
  • Summary: Nitrogen fertilization is essential for optimizing crop yields; however, it increases N2O emissions. The study objective was to compare N2O emissions resulting from application of commercially available enhanced-efficiency N fertilizers with emissions from conventional dry granular urea in irrigated cropping systems. Nitrous oxide emissions were monitored from corn (Zea mays L.) based rotations receiving fertilizer rates of 246 kg N ha-1 when in corn, 56 kg N ha-1 when in dry bean (Phaseolus vulgaris L.), and 157 kg N ha-1 when in barley (Hordeum vulgare L. ssp. vulgare). Cropping systems included conventional-till continuous corn (CT-CC), no-till continuous corn (NT-CC), no-till corn-dry bean (NT-CDb), and no-till corn-barley (NT-CB). In the NT-CC and CT-CC systems, a controlled-release, polymer-coated urea (ESN) and dry granular urea were compared. In the NT-CDb and NT-CB rotations, a stabilized urea source (SuperU) was compared with urea. Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. Cumulative growing season N2O emissions from urea and ESN application were not different under CT-CC, but ESN reduced N2O emissions 49% compared with urea under NT-CC. Compared with urea, SuperU reduced N2O emissions by 27% in dry bean and 54% in corn in the NT-CDb rotation and by 19% in barley and 51% in corn in the NT-CB rotation. This work shows that the use of no-till and enhanced-efficiency N fertilizers can potentially reduce N2O emissions from irrigated systems.
  • Authors:
    • Kohei, U.
    • Ebel, R.
    • Horowitz, J.
  • Source: Economic Information Bulletin
  • Volume: 70
  • Year: 2010
  • Summary: Most U.S. farmers prepare their soil for seeding and weed and pest control through tillage-plowing operations that disturb the soil. Tillage practices affect soil carbon, water pollution, and farmers' energy and pesticide use, and therefore data on tillage can be valuable for understanding the practice's role in reaching climate and other environmental goals. In order to help policymakers and other interested parties better understand U.S. tillage practices and, especially, those practices' potential contribution to climate-change efforts, ERS researchers compiled data from the Agricultural Resource Management Survey and the National Resources Inventory-Conservation Effects Assessment Project's Cropland Survey. The data show that approximately 35.5 percent of U.S. cropland planted to eight major crops, or 88 million acres, had no tillage operations in 2009.
  • Authors:
    • Gottlieb, J.
    • Horowitz, J.
  • Source: Economic Brief Number 15
  • Year: 2010
  • Authors:
    • Mikha,M. M.
    • Nielsen,D. C.
    • Halvorson,A. D.
    • Benjamin,J. G.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 3
  • Year: 2010
  • Summary: Crop biomass has been proposed as a source stock for bioethanol production. Levels of crop residue removal must be determined to prevent degradation of soil physical and chemical properties resulting from soil organic carbon (SOC) loss. Carbon inputs from crop residues and an estimate of inputs from roots and rhizodeposition (C return) were calculated and compared with changes in SOC after seven cropping seasons at Akron, CO. Tillage treatments included a chisel plow (CP) and a no-till (NT) treatment. A crop rotation alternating grasses and broadleaf crops was compared with continuous corn ( Zea mays L.). Irrigation treatments included water application to meet evapotranspiration demand or application only during the reproductive stage of each crop. Total C return varied from 25 Mg ha -1 for the delayed irrigation, crop rotation plots to 63 Mg ha -1 for the fully irrigated, continuous corn plots. The change in SOC in the surface 30 cm of soil varied from -0.8 Mg SOC ha -1 for the rotation plots to a gain of 2.8 Mg ha -1 for the continuous corn plots after 7 yr. Correlating crop residue input with change in SOC showed that about 4.6 Mg ha -1 yr -1 C return is needed to maintain SOC levels for NT cropping systems and an average of 7.4 Mg ha -1 yr -1 C return is needed to maintain SOC levels under chisel tillage. Continuous corn was the only system that consistently provided sufficient crop residue to maintain SOC levels. Residue removal for off-farm use should consider only amounts that can be harvested without decreasing SOC levels.
  • Authors:
    • Barfoot, P.
    • Brookes, G.
  • Source: AgBioForum
  • Volume: 13
  • Issue: 1
  • Year: 2010
  • Summary: This article updates the assessment of the impact commercialized agricultural biotechnology is having on global agriculture from an environmental perspective. It focuses on the impact of changes in pesticide use and greenhouse gas emissions arising from the use of biotech crops. The technology has reduced pesticide spraying by 352 million kg (-8.4%) and, as a result, decreased the environmental impact associated with herbicide and insecticide use on these crops (as measured by the indicator the environmental impact quotient) by 16.3%. The technology has also significantly reduced the release of greenhouse gas emissions from this cropping area, which, in 2008, was equivalent to removing 6.9 million cars from the roads.
  • Authors:
    • Sohngen, B.
    • Choi, S. W.
  • Source: Climatic Change
  • Volume: 99
  • Issue: 1-2
  • Year: 2010
  • Summary: This study investigates the cost of soil carbon sequestration in the Midwest US. The model addresses several missing components in earlier analyses: the link between the residue level choice and carbon payments, crop rotations, carbon loss when shifting from conservation to conventional tillage and the spatial pattern of carbon sequestration across different soil types. The results suggest that for $100 per metric ton of carbon, 1.5 million metric tons of carbon could be sequestered per year on the 19.9 million hectares of cropland in the study region. These estimates suggest less carbon potential than existing studies because the opportunity costs associated with conservation tillage are fairly high. Annual carbon rental payments are found to be more efficient, as expected, but for smaller programs, per hectare rental payments are not substantially more costly.
  • Authors:
    • Halvorson, A. D.
    • Archer, D. W.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 2
  • Year: 2010
  • Summary: Recent soil and crop management technologies have potential for mitigating greenhouse gas emissions; however, these management strategies must be profitable if they are to be adopted by producers. The economic feasibility of reducing net greenhouse gas emissions in irrigated cropping systems was evaluated for 5 yr on a Fort Collins clay loam soil (a fine-loamy, mixed, superactive, mesic Aridic Haplustalf). Cropping systems included conventional tillage continuous corn (Zea mays L.) (CT-CC), no-till continuous corn (NT-CC), and no-till corn-bean (NT-CB) including 1 yr soybean [Glycine max (L.) Merr.] and 1 yr dry bean (Phaseolus vulgaris L.). The study included six N fertilization rates ranging from 0 to 246 kg ha-1. Results showed highest average net returns for NT-CB, exceeding net returns for NT-CC and CT-CC by US$182 and US$228 ha-1, respectively, at economically optimum N fertilizer rates. Net global warming potential (GWP) generally increased with increasing N fertilizer rate with the exception of NT-CC, where net GWP initially declined and then increased at higher N rates. Combining economic and net GWP measurements showed that producers have an economic incentive to switch from CT-CC to NT-CB, increasing annual average net returns by US$228 ha-1 while reducing annual net GWP by 929 kg CO2 equivalents ha-1. The greatest GWP reductions (1463 kg CO2 equivalents ha-1) could be achieved by switching from CT-CC to NT-CC while also increasing net returns, but the presence of a more profitable NT-CB alternative means NT-CC is unlikely to be chosen without additional economic incentives.
  • Authors:
    • Singh, A.
    • Kumar, R.
    • Pathak, H.
    • Jain, N.
    • Sasmal, S.
    • Bhatia, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 136
  • Issue: 3
  • Year: 2010
  • Summary: No-till farming in wheat is being practiced in the rice-wheat system of the Indo-Gangetic plains of south Asia for resource conservation. No-tillage leads to mitigation of carbon dioxide emission, but may emit more nitrous oxide (N2O) as compared to conventional tillage reducing mitigation benefit. The aim of this study was assessment of N2O emission in wheat grown under conventional and no-tillage and its mitigation using two new nitrification inhibitors, viz. S-benzylisothiouronium butanoate (SBT-butanoate) and S-benzylisothiouronium furoate (SBT-furoate). Cumulative emission of N2O-N was higher under no-tillage by 12.2% with urea fertilization and from 4.1 to 4.8% for the inhibitor treatments as compared to the conventional tillage. In no-tillage total emission of N2O-N reduced from 0.43% of applied N with urea to 0.29% of applied N with SBT-furoate treatment. The N2O-N emissions in SBT-butanoate treatment were at par with the standard dicyandiamide (DCD) inhibitor treatment. Water-filled pore space (WFPS) was higher on most days under no-tillage, with the largest emissions (>1000 mu g N2O-N m(-2) day(-1)) coming with nitrification of ammonium-N present in soil below 60% WFPS. Carbon efficiency ratio was highest (48.1) from SBT-furoate treatment under conventional tillage. The nitrification inhibitors used in the study increased yield of wheat, reduced global warming potential by 8.9-19.5% over urea treatment and may be used to mitigate N2O emission.
  • Authors:
    • Blanco-Canqui, H.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 2
  • Year: 2010
  • Summary: Interest in producing cellulosic ethanol from renewable energy sources is growing. Potential energy crops include row crops such as corn (Zea mays L.), perennial warm-season grasses (WSGs), and short-rotation woody crops (SRWCs). However, impacts of growing dedicated energy crops as biofuel on soil and environment have not been well documented. This article reviews the (i) impacts of growing WSGs and SRWCs on soil properties, soil organic carbon (SOC) sequestration, and water quality, and (ii) performance of energy crops in marginal lands. Literature shows that excessive (>= 50%) crop residue removal adversely impacts sod and environmental quality as well as crop yields. Growing WSGs and SRWCs can be potential alternatives to crop residue removal as biofuel. Warm-season grasses and SRWCs can improve soil properties, reduce soil erosion, and sequester SOC. Crop residue removal reduces SOC concentration by 1 to 3 Mg ha(-1) yr(-1) in the top 10 cm, whereas growing WSGs and SRWCs increase SOC concentration while providing biofuel feedstocks. The WSGs can store SOC between 0 and 3 Mg C ha(-1) yr(-1) in the top 5 cm of soil, while the SRWCs can store between 0 and 1.6 Mg ha(-1) yr(-1) of SOC in the top 100 cm. The WSGs and SRWCs have more beneficial effects on soil and environment when grown in marginal lands than when grown in croplands or natural forests. Indeed, they can grow in nutrient-depleted, compacted, poorly drained, acid, and eroded soils. Development of sustainable systems of WSGs and SRWCs in marginal lands is a high priority.
  • Authors:
    • Vieira, F.
    • Bayer, C.
    • Zanatta, J.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Congress Symposium 4: Greenhouse gases from soils
  • Year: 2010
  • Summary: Emissions of N 2O were measured following cover crops management (oat - O and vetch - V) under tillage (CT) and no tillage (NT) in a silt loam Acrisol in South Brazil. Effects of tillage systems and residue management on N 2O emissions were examined over 55 days in 2007 and 54 days in 2008. Larger emissions were measured in 2008 compared to 2007. N 2O emissions increased in the presence of crops residues and were further increased in NT V/M in 2007 (19384 g N/m 2/ha) and in CT V/M in 2008 (431138 g N/m 2/ha) and they are related to high water content and available soil nitrogen. Smallest fluxes of N 2O were measured from the NT O/M treatments, which 28861 g N/m 2/ha in 2007 and 27419 g N/m 2/ha in 2008.