• Authors:
    • Kelly, K.
    • Phillips, F.
    • Baigent, R.
  • Source: Greenhouse Gases and Animal Agriculture
  • Year: 2007
  • Authors:
    • Chen, D.
    • Kelly, K.
    • Li, Y.
  • Source: ASA-CSSA-SSSA International Annual Meetings (November 4-8, 2007)
  • Year: 2007
  • Authors:
    • Denmead, O. T.
    • Kelly, K. B.
    • Baigent, R.
    • Leuning, R.
    • Phillips, F. A.
  • Source: Agricultural and Forest Meteorology
  • Volume: 143
  • Issue: 1-2
  • Year: 2007
  • Authors:
    • White, R. E.
    • Chapman, D. F.
    • Eckard, R. J.
  • Source: Australian Journal of Agricultural Research
  • Volume: 58
  • Issue: 12
  • Year: 2007
  • Authors:
    • McGregor, A.
    • Slattery, B.
    • Ugalde, D.
    • Brungs, A.
    • Kaebernick, M.
  • Source: Soil & Tillage Research
  • Volume: 97
  • Issue: 2
  • Year: 2007
  • Authors:
    • Barlow, E. W. R.
    • Whetton, P. H.
    • Webb, L. B.
  • Source: Australian Journal of Grape and Wine Research
  • Volume: 13
  • Issue: 3
  • Year: 2007
  • Authors:
    • Nicolardot, B.
    • Labreuche, J.
    • Grehan, E.
    • Merckx, R.
    • Oorts, K.
  • Source: Soil & Tillage Research
  • Volume: 95
  • Issue: 1-2
  • Year: 2007
  • Summary: The greenhouse gases CO2 and N2O emissions were quantified in a long-term experiment in northern France, in which no-till (NT) and conventional tillage (CT) had been differentiated during 32 years in plots under a maize-wheat rotation. Continuous CO2 and periodical N2O soil emission measurements were performed during two periods: under maize cultivation (April 2003-July 2003) and during the fallow period after wheat harvest (August 2003-March 2004). In order to document the dynamics and importance of these emissions, soil organic C and mineral N, residue decomposition, soil potential for CO2 emission and climatic data were measured. CO2 emissions were significantly larger in NT on 53% and in CT on 6% of the days. From April to July 2003 and from November 2003 to March 2004, the cumulated CO2 emissions did not differ significantly between CT and NT. However, the cumulated CO2 emissions from August to November 2003 were considerably larger for NT than for CT. Over the entire 331 days of measurement, CT and NT emitted 3160 +/- 269 and 4064 +/- 138 kg CO2-C ha(-1) respectively. The differences in CO2 emissions in the two tillage systems resulted from the soil climatic conditions and the amounts and location of crop residues and SOM. A large proportion of the CO2 emissions in NTover the entire measurement period was probably due to the decomposition of old weathered residues. NT tended to emit more N2O than CTover the entire measurement period. However differences were statistically significant in only half of the cases due to important variability. N2O emissions were generally less than 5 g N ha(-1) day(-1), except for a few dates where emission increased up to 21 g N ha(-1) day(-1). These N2O fluxes represented 0.80 +/- 0.15 and 1.32 +/- 0.52 kg N2O-N ba(-1) year(-1) for CT and NT, respectively. Depending on the periods, a large part of the N2O emissions occurred was probably induced by nitrification, since soil conditions were not favorable for denitrification. Finally, for the period of measurement after 32 years of tillage treatments, the NT system emitted more greenhouses gases (CO2 and N2O) to the atmosphere on an annual basis than the CT system. (C) 2006 Elsevier B.V. All rights reserved.
  • Authors:
    • Torbert, H. A.
    • Scopel, E.
    • Velazquez-Garcia, I.
    • Potter, K. N.
  • Source: Journal of Soil and Water Conservation
  • Volume: 62
  • Issue: 2
  • Year: 2007
  • Summary: While no-till management practices usually result in increased soil organic carbon (SOC) contents, the effect of residue removal with no-till is not well understood, especially in warmer climates. A multi-year study was conducted at six locations having a wide range of climatic conditions in central Mexico to determine the effect of varying rates of residue removal with no-till oil SOC. Mean annual temperatures ranged from 16 degrees C to 27 degrees C (61 degrees F to 81 degrees F). Mean annual rainfall ranged from 618 to 1099 min yr(-1) (24 to 43 in yr(-1)). Treatments consisted of annual moldboard plowing under residue and no-till with 100%, 66%, 33%, and no corn (Zea mays L.) residue retained oil the no-till surface. At five of the six locations, no-till with all surface residues removed maintained SOC levels above that of moldboard plowing which incorporated all residues. Retaining 100% of the crop residues with no-till always increased or maintained the SOC content. SOC increased in cooler climates, but as mean annual temperature increased, more retained crop residues were needed to increase the SOC. In tropical (mean annual temperature > 20 degrees C) conditions, 100% corn residue retention with no-till only maintained SOC levels. Mean annual temperature ad a greater impact oil SOC than did annual rainfall. It appears that, in warmer climates, residue in excess of that needed for erosion control may be used for animal fodder or energy production. At the higher temperatures, most of the residue will decompose if left oil the soil surface Without improving soil carbon contents.
  • Authors:
    • Valentini, R.
    • Tubaf, Z.
    • Sutton, M.
    • Manca, G.
    • Stefani, P.
    • Skiba, U.
    • Rees, R. M.
    • Baronti, S.
    • Raschi, A.
    • Neftel, A.
    • Nagy, Z.
    • Martin, C.
    • Kasper, G.
    • Jones, M.
    • Horvath, L.
    • Hensen, A.
    • Fuhrer, J.
    • Flechard, C.
    • Domingues, R.
    • Czobel, S.
    • Clifton-Brown, J.
    • Ceschia, E.
    • Campbell, C.
    • Amman, C.
    • Ambus, P.
    • Pilegaard, K.
    • Allard, V.
    • Soussana, J. F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 121
  • Issue: 1-2
  • Year: 2007
  • Summary: The full greenhouse gas balance of nine contrasted grassland sites covering a major climatic gradient over Europe was measured during two complete years. The sites include a wide range of management regimes (rotational grazing, continuous grazing and mowing), the three main types of managed grasslands across Europe (sown, intensive permanent and semi-natural grassland) and contrasted nitrogen fertilizer supplies. At all sites, the net ecosystem exchange (NEE) of CO2 was assessed using the eddy covariance technique. N2O emissions were monitored using various techniques (GC-cuvette systems, automated chambers and tunable diode laser) and CH4 emissions resulting from enteric fermentation of the grazing cattle were measured in situ at four sites using the SF6 tracer method. Averaged over the two measurement years, net ecosystem exchange (NEE) results show that the nine grassland plots displayed a net sink for atmospheric CO2 of -240 +/- 70 g C m(-2) year(-1) (mean confidence interval at p > 0.95). Because of organic C exports (from cut and removed herbage) being usually greater than C imports (from manure spreading), the average C storage (net biome productivity, NBP) in the grassland plots was estimated at -104 +/- 73 g cm(-2) year(-1) that is 43% of the atmospheric CO2 sink. On average of the 2 years, the grassland plots displayed annual N2O and CH4 (from enteric fermentation by grazing cattle) emissions, in CO2-C equivalents, of 14 +/- 4.7 and 32 +/- 6.8 g CO2-C equiv. m(-2) year(-1), respectively. Hence, when expressed in CO2-C equivalents, emissions of N2O and CH4 resulted in a 19% offset of the NEE sink activity. An attributed GHG balance has been calculated by subtracting from the NBP: (i) N2O and CH4 emissions occurring within the grassland plot and (ii) off-site emissions of CO2 and CH4 as a result of the digestion and enteric fermentation by cattle of the cut herbage. On average of the nine sites, the attributed GHG balance was not significantly different from zero (-85 +/- 77 g CO2-C equiv. m(-2) year(-1)).
  • Authors:
    • Dolfing, J.
    • Rappoldt, C.
    • Hol, J. M. G.
    • Mosquera, J.
  • Volume: 2010
  • Year: 2007
  • Summary: Soil compaction stimulates the emission of nitrous oxide (N2O) and methane (CH4) from agricultural soils. N2O and CH4 are potent greenhouse gases, with a global warming potential respectively 296 times and 23 times greater than CO2. Agricultural soils are an important source of N2O. Hence there is much interest in a systematic evaluation of management options that are available to minimize agricultural greenhouse gas emissions, in particular N2O soil emissions. One such option would be to minimize soil compaction due to the use of heavy machinery. Soil compaction in arable land is relatively general. Here we report that emissions of N2O and CH4 from an arable field where soil compaction was minimized through application of the so-called "rijpaden" (riding track) system was substantially lower than from plots where a traditional system was used. Laboratory experiments were used to underpin these observations. From these observations we developed a simple calculation model that relates N2O emission to gas filled pore space and soil respiration as input parameters. We suggest to implement the riding track system on clay rather than sand as farmers benefit from lower compaction in terms of lower risk of compaction and better accessibility of fields for work. The potential reduction of the N2O emission from arable farming in the Netherlands is estimated at ~169 ton N2O-N per year (~0.1 Mton CO2-equivalent). This calculation is based on several assumptions and would benefit from testing assumptions and monitoring effects in agricultural day to day practice.