• 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:
    • 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:
    • Schulze, E. D.
    • Houwelling, S.
    • Rivier, L.
    • Friedrich, R.
    • Scholz, Y.
    • Pregger, T.
    • Levin, I.
    • Piao, S. L.
    • Peylin, P.
    • Marland, G.
    • Paris, J. D.
    • Ciais, P.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 5
  • Year: 2010
  • Summary: We analyzed the magnitude, the trends and the uncertainties of fossil-fuel CO2 emissions in the European Union 25 member states (hereafter EU-25), based on emission inventories from energy-use statistics. The stability of emissions during the past decade at EU-25 scale masks decreasing trends in some regions, offset by increasing trends elsewhere. In the recent 4 years, the new Eastern EU-25 member states have experienced an increase in emissions, reversing after a decade-long decreasing trend. Mediterranean and Nordic countries have also experienced a strong acceleration in emissions. In Germany, France and United Kingdom, the stability of emissions is due to the decrease in the industry sector, offset by an increase in the transportation sector. When four different inventories models are compared, we show that the between-models uncertainty is as large as 19% of the mean for EU-25, and even bigger for individual countries. Accurate accounting for fossil CO2 emissions depends on a clear understanding of system boundaries, i.e. emitting activities included in the accounting. We found that the largest source of errors between inventories is the use of distinct systems boundaries (e.g. counting or not bunker fuels, cement manufacturing, non-energy products). Once these inconsistencies are corrected, the between-models uncertainty can be reduced down to 7% at EU-25 scale. The uncertainty of emissions at smaller spatial scales than the country scale was analyzed by comparing two emission maps based upon distinct economic and demographic activities. A number of spatial and temporal biases have been found among the two maps, indicating a significant increase in uncertainties when increasing the resolution at scales finer than ~200 km. At 100 km resolution, for example, the uncertainty of regional emissions is estimated to be 60 g C m-2 yr-1, up to 50% of the mean. The uncertainty on regional fossil-fuel CO2 fluxes to the atmosphere could be reduced by making accurate 14C measurements in atmospheric CO2, and by combining them with transport models.
  • 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:
    • Urquiaga, S.
    • Alves, B. J. R.
    • Giacomini, S. J.
    • Aita, C.
    • Denardin, J. E.
    • Dos Santos, H. P.
    • Dieckow, J.
    • Mielniczuk, J.
    • Bayer, C.
    • Zanatta, J. A.
    • Conceição, P. C.
    • Jantalia, C. P.
    • Boddey, R. M.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 2
  • Year: 2010
  • Summary: Conservation agriculture can provide a low-cost competitive option to mitigate global warming with reduction or elimination of soil tillage and increase soil organic carbon (SOC). Most studies have evaluated the impact of zero till (ZT) only on surface soil layers (down to 30 cm), and few studies have been performed on the potential for C accumulation in deeper layers (0-100 cm) of tropical and subtropical soils. In order to determine whether the change from conventional tillage (CT) to ZT has induced a net gain in SOC, three long-term experiments (15-26 years) on free-draining Ferralsols in the subtropical region of South Brazil were sampled and the SOC stocks to 30 and 100 cm calculated on an equivalent soil mass basis. In rotations containing intercropped or cover-crop legumes, there were significant accumulations of SOC in ZT soils varying from 5 to 8 Mg ha-1 in comparison with CT management, equivalent to annual soil C accumulation rates of between 0.04 and 0.88 Mg ha-1. However, the potential for soil C accumulation was considerably increased (varying from 0.48 to 1.53 Mg ha-1 yr-1) when considering the soil profile down to 100 cm depth. On average the estimate of soil C accumulation to 100 cm depth was 59% greater than that for soil C accumulated to 30 cm. These findings suggest that increasing sampling depth from 30 cm (as presently recommended by the IPCC) to 100 cm, may increase substantially the estimates of potential CO2 mitigation induced by the change from CT to ZT on the free-draining Ferralsols of the tropics and subtropics. It was evident that that legumes which contributed a net input of biologically fixed N played an important role in promoting soil C accumulation in these soils under ZT, perhaps due to a slow-release of N from decaying surface residues/roots which favored maize root growth.
  • Authors:
    • Deka, S.
    • Kattarkandi, B.
    • Singh, S.
    • Choudhary, R.
  • Source: Current Advances in Agricultural Sciences
  • Volume: 2
  • Issue: 1
  • Year: 2010
  • Summary: Global warming poses a potential threat to agricultural production and productivity. Maize ( Zea mays L.) is one of the most important cereals of the world and provides more human food than any other cereal. The study reported in this paper, uses field experiments and simulation models to understand the impact of changing climate on growth and yield of maize plant. In field environment, growth and yield of maize was greatly affected by temperature changes associated with sowing dates. Yield was reduced in late sown crops due to the harmful effect of chilling temperature. Application of irrigation had positive effect on crop growth. Biomass and grain yield as well as other yield attributes were higher in irrigated treatments than the rainfed one. InfoCrop model satisfactorily simulated crop phenology, leaf area index, dry matter production and yield of maize in Delhi. Impact assessment of maize yield to temperature rise showed reduction in yield in both Delhi and Patna with atmospheric temperature rise during the kharif season with percentage reduction was similar in both locations. In rabi crop, future temperature increase initially showed a positive response up to 2degreesC. Climate change is projected to reduce kharif maize yield in India, however, projected increase in rainfall may be beneficial in some locations during rabi season.
  • Authors:
    • Wang, L.
    • Chen, Z.
    • Chen, X.
    • Wan, Y.
    • Yang, W.
    • Gong, W.
    • Yan, Y.
  • Source: PLANT PRODUCTION SCIENCE
  • Volume: 13
  • Issue: 4
  • Year: 2010
  • Summary: The relay strip intercropping system of wheat-corn-soybean is widely used in southwest China. However, it is hard to obtain a stable production of soybean with this system, since soybean plants grow under shading by corn; the stems are thinner and susceptible to lodging. We examined the effects of seed treatment with uniconazole powder (0, 2, 4 and 8 mg kg -1 seed) on the growth of soybean seedlings under relay strip intercropping, some morphological characteristics and yield. The seedling height, first internode length, cotyledonary node height and leaf area per plant were decreased, while the stem diameter, root dry weight, shoot dry weight, root volume, leaf greenness and root to shoot dry weight ratio were increased by uniconazole treatment. The root vigor and root active absorption area were also increased significantly by uniconazole treatment. Moreover, 2 and 4 mg kg -1 uniconazole powder treatment increased shoot dry weight, number of pods per plant, number of seeds per pod and seed yield significantly. Thus, the results suggested that seed treatment with uniconazole powder at a suitable concentration can improve soybean seedling growth, resist the lodging and also increase the seed yield under shading by corn in relay strip intercropping system.
  • 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.
  • Authors:
    • Chen, C.
    • Xu, Z.
    • Wu, H.
    • Zhou, X.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Working Group 3.5 Paddy soils and water scarcity
  • Year: 2010
  • Summary: Winter cover crops are not only one of effective agricultural management practices to control weeds but also can improve soil fertility, resulting in increasing crop productions. Up to now, however, little is known about information on how much of soil soluble organic carbon (C) incorporates into the soils applied with winter cover crops, which is a prerequisite to design strategies that improve C sequestration in agricultural ecosystems. The aims of this study were to: (1) assess the effects of winter cover crops on soluble organic carbon (SOC) pools using different extraction methods (KCl extractable organic C; microbial biomass) and microbial community functional diversity, and (2) quantify how much of the potentially mineralizable organic C pools (C 0) incorporates into the soils and associated half-life of SOC remaining under seven cover crops and nil-crop control (CK) in temperate agricultural soils of southern Australia. Cover crop treatments are cereal rye, wheat, saia oats, vetch, field peas, mustard and the mixture of cereal rye and vetch. Results showed that the CK treatment had higher soil moisture content and lower soluble organic nitrogen (SON) compared to the cover crop treatments. Among the cover crop treatments, there was significantly higher SON in the wheat, oats and vetch treatments than in the other treatments. The oats treatment had the highest amount of cumulative CO 2-C than any other treatments over one-month incubation experiment. An exponential regression approach for C mineralization was used to estimate C o and soil samples under the cover crops can be divided into four groups depending on C o. The principal component analysis of the MicroResp TM profiles showed that the CK treatment was significantly different from the cover crop treatments. The cover crop treatments with wheat, vetch and peas as well as mustard form a cluster which was significantly different from the other clusters. In addition, the vetch, field peas and mustard treatments showed higher Shannon diversity H and Evenness (E) and Simpson diversity H compared to the other cover crop treatments with the lowest Shannon H and E at CK. In conclusion, overall, the vetch and field peas as well as wheat winter cover crop may be better management practices for agricultural ecosystems in southern Australia.