191. The Bioeconomic Potential for Agroforestry in Australia's Northern Grazing Systems

• Authors:
  • Hoffmann, M.
  • Donaghy, P.
  • Stunzer, A.
  • Bray, S.
  • Gowen, R.
  • Rolfe, J.
  • Stephens, M.
• Source: Small-Scale Forestry
• Volume: 9
• Issue: 4
• Year: 2010

192. Soil-atmosphere exchange of CH(4), CO, N(2)O and NO(x) and the effects of land-use change in the semiarid Mallee system in Southeastern Australia

• Authors:
  • Meyer,C. P. (M.)
  • Kirstine, W.
  • Galbally, I.
  • Wang, Y. -P.
• Source: Global Change Biology
• Volume: 16
• Issue: 9
• Year: 2010

193. Impacts of fertilisers and legumes on N(2)O and CO(2) emissions from soils in subtropical agricultural systems: A simulation study

• Authors:
  • Radford, B. J.
  • Thornton, C. M.
  • Huth, N. I.
  • Thorburn, P. J.
• Source: Agriculture, Ecosystems & Environment
• Volume: 136
• Issue: 3-4
• Year: 2010

194. Emerging opportunities and challenges for Australian broadacre agriculture

• Authors:
  • Keating, B. A.
  • Carberry, P. S.
• Source: Crop & Pasture Science
• Volume: 61
• Issue: 4
• Year: 2010

195. An assessment of greenhouse gas emissions: implications for the Australian cotton industry

• Authors:
  • Maraseni, T. N.
  • Cockfield, G.
  • Maroulis, J.
• Source: The Journal of Agricultural Science
• Volume: 148
• Year: 2010

196. An assessment of greenhouse gas emissions from the Australian vegetables industry

• Authors:
  • Maraseni, T. N.
  • Cockfield, G.
  • Maroulis, J.
• Source: Journal of Environmental Science and Health, Part B: Pesticides, Food Contaminants, and Agricultural Wastes
• Volume: 45
• Issue: 6
• Year: 2010

197. Life cycle assessment of Australian sugarcane production with a focus on sugarcane growing

• Authors:
  • Renouf, M. A.
  • Wegener, M. K.
  • Pagan, R. J.
• Source: The International Journal of Life Cycle Assessment
• Volume: 15
• Issue: 9
• Year: 2010

198. Progress in breeding perennial grains.

• Authors:
  • DeHaan,L. R.
  • Cox,C. M.
  • Tassel,D. L. van
  • Cox,T. S.
• Source: Crop & Pasture Science
• Volume: 61
• Issue: 7
• Year: 2010
• Summary: Annual cereal, legume and oilseed crops remain staples of the global food supply. Because most annual crops have less extensive, shorter-lived root systems than do perennial species, with a correspondingly lower capacity to manage nutrients and water, annual cropping systems tend to suffer higher levels of soil erosion and generate greater water contamination than do perennial systems. In an effort to reduce soil degradation and water contamination simultaneously - something that neither no-till nor organic cropping alone can accomplish - researchers in the United States, Australia and other countries have begun breeding perennial counterparts of annual grain and legume crops. Initial cycles of hybridization, propagation and selection in wheat, wheatgrasses, sorghum, sunflower and Illinois bundleflower have produced perennial progenies with phenotypes intermediate between wild and cultivated species, along with improved grain production. Further breeding cycles will be required to develop agronomically adapted perennial crops with high grain yields.

199. Influence of biochars on nitrous oxide emission and nitrogen leaching from two contrasting soils

• Authors:
  • Kathuria, A.
  • Cowie, A. L.
  • Singh, B.
  • Hatton, B. J.
  • Singh, B. P.
• Source: Journal of Environmental Quality
• Volume: 39
• Issue: 4
• Year: 2010
• Summary: The influence of biochar on nitrogen (N) transformation processes in soil is not fully understood. This study assessed the influence of four biochars (wood and poultry manure biochars synthesized at 400°C, nonactivated, and at 550°C, activated, abbreviated as: W400, PM400, W550, PM550, respectively) on nitrous oxide (N2O) emission and N leaching from an Alfisol and a Vertisol. Repacked soil columns were subjected to three wetting-drying (W-D) cycles to achieve a range of water-filled pore space (WFPS) over a 5-mo period. During the first two W-D cycles, W400 and W550 had inconsistent effects on N2O emissions and the soils amended with PM400 produced higher N2O emissions relative to the control. The initially greater N2O emission from the PM400 soils was ascribed to its higher labile intrinsic N content than the other biochars. During the third W-D cycle, all biochar treatments consistently decreased N2O emissions, cumulatively by 14 to 73% from the Alfisol and by 23 to 52% from the Vertisol, relative to their controls. In the first leaching event, higher nitrate leaching occurred from the PM400-amended soils compared with the other treatments. In the second event, the leaching of ammonium was reduced by 55 to 93% from the W550- and PM550-Alfisol and Vertisol, and by 87 to 94% from the W400- and PM400-Vertisol only (cf. control). We propose that the increased effectiveness of biochars in reducing N2O emissions and ammonium leaching over time was due to increased sorption capacity of biochars through oxidative reactions on the biochar surfaces with ageing.

200. Towards an agronomic assessment of N2O emissions: a case study for arable crops

• Authors:
  • van Groenigen, K. J.
  • van Kessel, C.
  • Oenema, O.
  • Velthof, G. L.
  • van Groenigen, J. W.
• Source: European Journal of Soil Science
• Volume: 61
• Issue: 6
• Year: 2010
• Summary: Agricultural soils are the main anthropogenic source of nitrous oxide (N2O), largely because of nitrogen (N) fertilizer use. Commonly, N2O emissions are expressed as a function of N application rate. This suggests that smaller fertilizer applications always lead to smaller N2O emissions. Here we argue that, because of global demand for agricultural products, agronomic conditions should be included when assessing N2O emissions. Expressing N2O emissions in relation to crop productivity (expressed as above-ground N uptake: "yield-scaled N2O emissions") can express the N2O efficiency of a cropping system. We show how conventional relationships between N application rate, N uptake and N2O emissions can result in minimal yield-scaled N2O emissions at intermediate fertilizer-N rates. Key findings of a meta-analysis on yield-scaled N2O emissions by non-leguminous annual crops (19 independent studies and 147 data points) revealed that yield-scaled N2O emissions were smallest (8.4 g N2O-N kg-1N uptake) at application rates of approximately 180-190 kg Nha-1 and increased sharply after that (26.8 g N2O-N kg-1 N uptake at 301 kg N ha-1). If the above-ground N surplus was equal to or smaller than zero, yield-scaled N2O emissions remained stable and relatively small. At an N surplus of 90 kg N ha-1 yield-scaled emissions increased threefold. Furthermore, a negative relation between N use efficiency and yield-scaled N2O emissions was found. Therefore, we argue that agricultural management practices to reduce N2O emissions should focus on optimizing fertilizer-N use efficiency under median rates of N input, rather than on minimizing N application rates.