• Authors:
    • Kelly, K.
    • Edis, R. B.
    • Li, Y.
    • Chen, D.
    • Turner, D.
  • Source: SuperSoil: 3rd Australian New Zealand Soils Conference
  • Year: 2004
  • Authors:
    • Luo, J.
    • Hedley, C. B.
    • Bhandral, R.
    • Bolan, N. S.
    • Saggar, S.
  • Source: New Zealand Journal of Agricultural Research
  • Volume: 47
  • Issue: 4
  • Year: 2004
  • Summary: The agricultural sector in New Zealand is the major contributor to ammonia (NH3), nitrous oxide (N2O), and methane (CH4) emissions to the atmosphere. These gases cause environmental degradation through their effects on soil acidification, eutrophication, and stratospheric ozone depletion. With its strong agricultural base and relatively low level of heavy industrial activity, New Zealand is unique in having a greenhouse gas emissions inventory dominated by the agricultural trace gases, CH4 and N2O, instead of carbon dioxide which dominates in most other countries. About 96% of this anthropogenic CH4 is emitted by ruminant animals as a by-product during the process of enteric fermentation. Methane is also produced by anaerobic fermentation of animal manure and many other organic substrates.
  • Authors:
    • Soil Management Technical Working Group
    • Soussana,J. -F
    • Loiseau,P.
    • Vuichard,N.
    • Ceschia,E.
    • Balesdent,J.
    • Chevallier,T.
    • Arrouays,D.
  • Source: Soil Use and Management
  • Volume: 20
  • Issue: 2
  • Year: 2004
  • Summary: Abstract. Temperate grasslands account for c. 20% of the land area in Europe. Carbon accumulation in grassland ecosystems occurs mostly below ground and changes in soil organic carbon stocks may result from land use changes (e.g. conversion of arable land to grassland) and grassland management. Grasslands also contribute to the biosphere atmosphere exchange of non-CO2 radiatively active trace gases, with fluxes intimately linked to management practices. In this article, we discuss the current knowledge on carbon cycling and carbon sequestration opportunities in temperate grasslands. First, from a simple two-parameter exponential model fitted to literature data, we assess soil organic carbon fluxes resulting from land use change (e.g. between arable and grassland) and from grassland management. Second, we discuss carbon fluxes within the context of farming systems, including crop grass rotations and farm manure applications. Third, using a grassland ecosystem model (PaSim), we provide estimates of the greenhouse gas balance, in CO2 equivalents, of pastures for a range of stocking rates and of N fertilizer applications. Finally, we consider carbon sequestration opportunities for France resulting from the restoration of grasslands and from the de-intensification of intensive livestock breeding systems. We emphasize major uncertainties concerning the magnitude and non-linearity of soil carbon stock changes in agricultural grasslands as well as the emissions of N2O from soil and of CH4 from grazing livestock.
  • Authors:
    • Carter, A. D.
    • Harrison, R.
    • Bradley, R. I.
    • King, J. A.
  • Source: Soil Use and Management
  • Volume: 20
  • Issue: 4
  • Year: 2004
  • Summary: The potential for soil organic carbon sequestration, energy savings and the reduction of the emission of greenhouse gases were investigated for a range of changes in the management of tilled land and managed grassland. These parameters were modelled on a regional basis, according to local soils and crop rotations in England, and avoided the use of soil related indices. The largest carbon sequestration and saving contribution possible comes from an increase in the proportion of permanent woodland, such that a 10% change in land use could amount to 9 Mt C yr22121 in the initial years (arable and grassland). Changes in arable management could make a significant contribution to an abatement strategy if carried out in concert with greater use of permanent conservation field margins, increased returns of crop residues and reduced tillage systems, contributing 1.3 Mt C yr22121 in the initial years. It should be noted, however, that true soil carbon sequestration would be only a minor component of this (125 kt C yr22121), the main part being savings on CO2 emissions from reduced energy use, and lower N2O emissions from reduced use of inorganic nitrogen fertilizer.
  • Authors:
    • Smith, P.
    • Powlson, D. S.
    • Falloon, P.
  • Source: Soil Use and Management
  • Volume: 20
  • Issue: 2
  • Year: 2004
  • Summary: Field margins are a valuable resource in the farmed landscape, providing numerous environmental benefits. We present a preliminary analysis of the carbon mitigation potential of different field margin management options for Great Britain, calculated using data from long-term experiments and literature estimates. The carbon sequestration potential of the individual options investigated here varies from 0.1 to 2.4% of 1990 UK CO2-C emissions, or 0.7-20% of the Quantified Emission Limitation Reduction Commitment (QELRC). The scenarios investigated covered three possible margin widths and options for the management of margins at each width (viz. grass strips, hedgerows and tree strips). Scenarios involving margin widths of 2, 6 or 20m would require approximately 2.3, 6.7 or 21.3% of the total arable area of Great Britain, respectively. Scenarios including tree strips offered the greatest potential for carbon sequestration, since large amounts would be accumulated in above-ground biomass in addition to that in soil. We also accounted for the possible impacts of changed land management on trace gas fluxes, which indicated that any scenario involving a change from arable to grass strip, hedgerow or tree strip would significantly reduce N2O emissions, and thus further increase carbon mitigation potential. There would also be considerable potential for including the scenarios investigated here with other strategies for the alternative management of UK arable land to identify optimal combinations. We assumed that it would take 50-100 years for soil carbon to reach a new equilibrium following a land use change. More detailed analyses need to be conducted to include environmental benefits, socioeconomic factors and the full system carbon balance.
  • Authors:
    • Scott, A.
    • Ball, B. C.
    • McTaggart, I. P.
    • Akiyama, H.
  • Source: Water, Air, & Soil Pollution
  • Volume: 156
  • Issue: 1-4
  • Year: 2004
  • Summary: Agricultural soil is a major source of nitrous oxide (N2O), nitric oxide (NO) and ammonia (NH3). Little information is available on emissions of these gases from soils amended with organic fertilizers at different soil water contents. N2O, NO and NH3 emissions were measured in large-scale incubations of a fresh sandy loam soil and amended with four organic fertilizers, [poultry litter (PL), composted plant residues (CP), sewage sludge pellets (SP) and cattle farm yard manure (CM)], urea fertilizer (UA) or a zero-N control (ZR) for 38 days. Fertilizers were added to soil at 40, 60 or 80% water-filled pore space (WFPS). The results showed that urea and organic fertilizer were important sources of N2O and NO. Total N2O and NO emissions from UA ranged from 0.04 to 0.62%, and 0.23 to 1.55% of applied N, respectively. Total N2O and NO emissions from organic fertilizer treatments ranged from 0.01 to 1.65%, and <0.01 to 0.55% of applied N, respectively. The lower N2O and NO emissions from CP and CM suggested that applying N is these forms could be a useful mitigation option. Comparison of the NO-N/N2O-N ratio suggested that nitrification was more dominant in UA whereas denitrification was more dominant in the organic fertilizer treatments. Most N was lost from PL and UA as NH3, and this was not influenced significantly by WFPS. Emissions of NH3 from UA and PL ranged from 62.4 to 69.6%, and 3.17 to 6.11% of applied N, respectively.
  • Authors:
    • Kreye, H.
  • Source: Bulletin OILB/SROP
  • Volume: 27
  • Issue: 10
  • Year: 2004
  • Summary: In a long-term field trial, the effects of three different tillage systems on harmful organisms and yield were investigated. The focus was on fungal diseases, weeds and slugs. With the ploughing system as the standard, a non-inversion/conservation tillage and a direct drilling/no till system were compared with one another. The crop rotation oilseed rape-wheat-barley, which was established in 1995, was reconverted into a crop rotation oilseed rape-wheat-wheat in 1998 due to problems with volunteer wheat in the following barley in the two ploughless tillage systems. The occurrence of Phoma root-collar and stem disease, the most important in Germany, was not affected in comparison over the years by the intensity of the cultivation. For Sclerotinia stem rot, a correlation could only be determined with the tillage systems in one year of the trial series. The infection became more severe with decreasing intensity of soil cultivation. Whether this result can be reproduced in future growing seasons remains to be seen. Effects on the incidence of Verticillium longisporum could not be determined. Other diseases arose only sporadically at very low levels. However, in comparison, the occurrence of weeds was affected significantly. The amount of grass weed species ( Alopecurus myosuroides, Apera spica-venti, volunteer barley) increased in the systems without ploughing. The effect on dicotyledonous weed species was dependent on the particular species. In individual years, heavy slug damage could be correlated with direct drilling system.
  • Authors:
    • Chapman, D. F.
    • White, R. E.
    • Chen, D.
    • Eckard, R. J.
  • Source: Australian Journal of Agricultural Research
  • Volume: 54
  • Year: 2003
  • Authors:
    • Wiemken, A.
    • Boller, T.
    • Mader, P.
    • Ineichen, K.
    • Sieverding, E.
    • Oehl, F.
  • Source: Applied and Environmental Microbiology
  • Volume: 69
  • Issue: 5
  • Year: 2003
  • Summary: The impact of land use intensity on the diversity of arbuscular mycorrhizal fungi (AMF) was investigated at eight sites in the "three-country corner" of France, Germany, and Switzerland. Three sites were low-input, species-rich grasslands. Two sites represented low- to moderate-input farming with a 7-year crop rotation, and three sites represented high-input continuous maize monocropping. Representative soil samples were taken, and the AMF spores present were morphologically identified and counted. The same soil samples also served as inocula for "AMF trap cultures" with Plantago lanceolata, Trifolium pratense, and Lolium perenne. These trap cultures were established in pots in a greenhouse, and AMF root colonization and spore formation were monitored over 8 months. For the field samples, the numbers of AMF spores and species were highest in the grasslands, lower in the low- and moderate-input arable lands, and lowest in the lands with intensive continuous maize monocropping. Some AMF species occurred at all sites ("generalists"); most of them were prevalent in the intensively managed arable lands. Many other species, particularly those forming sporocarps, appeared to be specialists for grasslands. Only a few species were specialized on the arable lands with crop rotation, and only one species was restricted to the high-input maize sites. In the trap culture experiment, the rate of root colonization by AMF was highest with inocula from the permanent grasslands and lowest with those from the high-input monocropping sites. In contrast, AMF spore formation was slowest with the former inocula and fastest with the latter inocula. In conclusion, the increased land use intensity was correlated with a decrease in AMF species richness and with a preferential selection of species that colonized roots slowly but formed spores rapidly.
  • Authors:
    • Bouma, J.
    • Marinissen, J.
    • Jongmans, A.
    • Pulleman, M.
  • Source: Soil Use and Management
  • Volume: 19
  • Issue: 2
  • Year: 2003
  • Summary: We compared the effects of conventional and organic arable farming on soil organic matter (SOM) content, soil structure, aggregate stability and C and N mineralization, which are considered important factors in defining sustainable land management. Within one soil series, three different farming systems were selected, including a conventional and an organic arable system and permanent pasture without tillage. The old pasture represents optimal conditions in terms of soil structure and organic matter inputs and is characterized by high earthworm activity. More than 70 years of different management has caused significant differences in soil properties. SOM content, mineralization, earthworm activity and water-stable aggregation decreased as a result of tillage and arable cropping when compared with pasture, but were significantly greater under organic farming than under conventional farming. Total SOM contents between 0 and 20 cm depth amounted to 15, 24 and 46 g kg-1 for the conventional arable, organic arable and permanent pasture fields, respectively. Although less sensitive to slaking than the conventionally managed field, the soil under organic farming was susceptible to compaction when high pressures were exerted on the soil under wet conditions. The beneficial effects of organic farming are generally associated with soil biochemical properties, but soil physical aspects should also be considered. Depending on soil type and climate, organic farmers need to be careful not to destroy the soil structure, so that they can enjoy maximum advantage from their organic farming systems.