• 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:
    • Scholefield, D.
    • Dhanoa, M. S.
    • Lane, S.
    • Kingston, H.
    • Donovan, N.
    • Cuttle, S.
    • Chambers, B.
    • Chadwick, D.
    • Butler, M.
    • Ashleee, N.
    • Thorman, R.
    • Cardenas, L. M.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 136
  • Issue: 3-4
  • Year: 2010
  • Summary: The objective of the present study was to measure emissions of N2O from fertilized grazed grassland that can be used to add valuable information to the limited existing data on N2O fluxes from grazed grassland and aid the development of new country-specific EFs for direct emissions from soils in the UK. This was done by evaluating the effect on N2O emissions of inorganic fertiliser N applied to grazed grassland soils over the range of N inputs 0-350 kg ha(-1). Nitrous oxide fluxes were measured using closed static chambers at 3 sites in England and Wales over a two-year period. Cumulative fluxes were calculated and the total emission regressed against applied inorganic fertiliser N in order to estimate the emission factor for N2O emissions from soils. The data showed that, the emission factor for N2O from inorganic fertiliser applied to grazed grassland soils in the UK differs from the IPCC default value of 1.25%. A nonlinear response of N2O emissions to fertiliser N application rates was observed. Annual emissions of N2O were estimated from a modelled function fitted to the measured data and after subtraction of the background flux resulted in emissions of 0.5 and 3.9 kg N2O-N ha(-1) yr(-1) for an application of 100 kg N for three locations in the UK, one in the East and the other two in the West of the UK (after combining the data from two sites), respectively. (C) 2009 Elsevier B.V. All rights reserved.
  • 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:
    • Sherlock, R. R.
    • Wells, N. S.
    • O'Callaghan, M.
    • Condron, L. M.
    • Ray, J. L.
    • Bertram, J. E.
    • Clough, T. J.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 3
  • Year: 2010
  • Summary: Low-temperature pyrolysis of biomass produces a product known as biochar. The incorporation of this material into the soil has been advocated as a C sequestration method. Biochar also has the potential to influence the soil N cycle by altering nitrification rates and by adsorbing NH or NH3. Biochar can be incorporated into the soil during renovation of intensively managed pasture soils. These managed pastures are a significant source of N2O, a greenhouse gas, produced in ruminant urine patches. We hypothesized that biochar effects on the N cycle could reduce the soil inorganic-N pool available for N2O-producing mechanisms. A laboratory study was performed to examine the effect of biochar incorporation into soil (20 Mg ha-1) on N2O-N and NH3-N fluxes, and inorganic-N transformations, following the application of bovine urine (760 kg N ha-1). Treatments included controls (soil only and soil plus biochar), and two urine treatments (soil plus urine and soil plus biochar plus urine). Fluxes of N2O from the biochar plus urine treatment were generally higher than from urine alone during the first 30 d, but after 50 d there was no significant difference (P = 0.11) in terms of cumulative N2O-N emitted as a percentage of the urine N applied during the 53-d period; however, NH3-N fluxes were enhanced by approximately 3% of the N applied in the biochar plus urine treatment compared with the urine-only treatment after 17 d. Soil inorganic-N pools differed between treatments, with higher NH concentrations in the presence of biochar, indicative of lower rates of nitrification. The inorganic-N pool available for N2O-producing mechanisms was not reduced, however, by adding biochar.
  • 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:
    • Inomoto, M. M.
    • Asmus, G. L.
  • Source: Plant disease: an international journal of applied plant pathology
  • Volume: 94
  • Issue: 8
  • Year: 2010
  • Summary: Taking into account that information about the host status of cover crops for Pratylenchus brachyurus is scarce or contradictory, this study was undertaken to assess the host status of selected graminaceous cover crops by estimating nematode reproduction and their ability to decrease the nematode density in glasshouse conditions. Furthermore, the reproductive fitness of three P. brachyurus populations was assessed for Brachiaria grasses. Silage and forage sorghum proved to be good hosts for P. brachyurus; consequently, they should be avoided in fields infested with this lesion nematode, mainly before susceptible crop such as soybean, common bean, cowpea, and cotton. Dictyoneura grass, the pearl millet cv. ADR 300, and black oat were poor hosts for P. brachyurus but may increase densities of this nematode over time. Consequently, these cover crops might be used in infested fields for only short periods, because they could increase the P. brachyurus population density slowly but progressively.
  • Authors:
    • Ginovart, M.
    • Josa, R.
    • Sole, A.
  • Source: International Agrophysics
  • Volume: 24
  • Issue: 2
  • Year: 2010
  • Summary: In an experiment conducted in NE Spain, cereals and legumes were rotated for seven cycles using two different tillage techniques - conventional tillage and direct drilling (no-tillage: NT). Straw was removed after harvesting in both tillage systems. With NT, more than 30% of the soil surface was still covered by residues (stubble) at sowing. The soil was Calcic Cambisol and the climate aridity index was 0.76. The climatic water balance was negative, at -187 mm y(-1) from 1950 to 1980. The aims of the study were to determine the effect of tillage system on 2-D macroporosity by micromorphology, and bulk density (excavation method) of the upper layer of the ploughed horizon. To identify differences, either parametric or nonparametric statistical tests were performed depending on sample size. Direct drilling with residue removal affected bulk density, macroporosity and mean macropore area in the top 10 cm of the profile. The same effects were observed under conventional tillage. The upper layer of the studied horizon had higher total porosity than the layer beneath with both treatments. The upper layer of the horizon showed unfavourable physical conditions with direct drilling.
  • Authors:
    • Maeder, P.
    • Niggli, U.
    • Wiemken, A.
    • Burger, D.
    • Berner, A.
    • Krauss, M.
  • Source: Soil Use and Management
  • Volume: 26
  • Issue: 1
  • Year: 2010
  • Summary: To promote conservation tillage in organic farming systems, weed control and ley removal within arable-ley rotations need to be optimized. A long-term field trial was thus established in Frick, Switzerland in 2002 on a clayey soil and with a mean precipitation of 1000 mm/year. The tillage experiment distinguished between conventional tillage with mouldboard ploughing (CT, 15 cm depth) and reduced tillage (RT), including a chisel plough (15 cm) and a stubble cleaner (5 cm). Results of a 2-year grass-clover ley (2006/2007) and silage maize (2008) are presented. Due to dry conditions, mean grass-clover yields were 25% higher in RT than in CT, indicating better water retention of RT soils. Clover cover and mineral contents of the fodder mixture were also higher in RT. The ley was successfully removed in autumn 2007 in RT plots, and a winter pea catch crop was sown before maize. In CT, ploughing took place in spring 2008. Maize yields were 34% higher in RT than in CT, despite a two- to three-fold higher but still tolerable weed infestation. Maize in RT plots benefited from an additional 61.5 kg of easily decomposable organic N/ha incorporated into the soil via the pea mulch. Measurement of arbuscular mycorrhizal colonization of maize roots indicated a similar mechanical disturbance of the topsoil through the reduced ley removal system compared with ploughing. It is suggested that RT is applicable in organic farming, even in arable-ley rotations, but long-term effects need further assessment.