- Authors:
- Source: The CCRSPI Conference
- Year: 2011
- Authors:
- Chen, D.
- Mahoney, M.
- Davies, R.
- Sultana, H.
- Suter, H.
- Source: The CCRSPI Conference
- Year: 2011
- Authors:
- Kiese, R.
- Butterbach-Bahl, K.
- Reeves, S. H.
- Dalal, R. C.
- Wang, W.
- Source: Global Change Biology
- Volume: 17
- Issue: 10
- Year: 2011
- Authors:
- Loughran, R.
- Chappell, A.
- Rossel, R. A. V.
- Source: Journal of Geophysical Research - Earth Surface
- Volume: 116
- Year: 2011
- Authors:
- Source: Biomass and Bioenergy
- Volume: 35
- Issue: 5
- Year: 2011
- Authors:
- Denmead,O. Tom
- Kinsela,Andrew S.
- Reynolds,Jason K.
- Melville,Michael D.
- Macdonald,Bennett C. T.
- White,Ian
- Source: Soil Research
- Volume: 49
- Issue: 6
- Year: 2011
- Authors:
- Cockfield, G.
- Maraseni, T. N.
- Source: Agricultural Systems
- Volume: 104
- Issue: 6
- Year: 2011
- Authors:
- Mollah, M.
- Partington, D.
- Fitzgerald, G.
- Source: Crop and Pasture Science
- Volume: 62
- Issue: 10
- Year: 2011
- Summary: Carbon dioxide (CO2) is the most important greenhouse gas, predicted to increase globally from currently 386 to 550 μmol mol–1 by 2050 and cause significant stimulation to plant growth. Consequently, in 2007 and 2008, Australian grains free-air carbon dioxide enrichment (AGFACE) facilities were established at Horsham (36°45′07″S lat., 142°06′52″E long., 127 m elevation) and Walpeup (35°07′20″S lat., 142°00′18″E long., 103 m elevation) in Victoria, Australia to investigate the effects of elevated CO2, water supply and nitrogen fertiliser on crop growth. Understanding the distribution patterns of CO2 inside AGFACE rings is crucial for the interpretation of the crop growth data. In the AGFACE system, the engineering performance goal was set as having at least 80% of the ring area with a CO2 concentration [CO2] at or above 90% of the target concentration at the ring-centre for 80% of the time. The [CO2] was highly variable near the ring-edge where CO2 is emitted and declined non-linearly with the distance downwind and wind speeds. Larger rings maintained the target [CO2] of 550 μmol mol–1 at the ring-centres better than the smaller rings. The spatial variation of [CO2] depended on ring size and the gap between fumigation and canopy heights but not on wind speeds. The variations in the inner 80% of the rings were found to be higher in smaller rings, implying that the larger rings had more areas of relatively uniform [CO2] to conduct experiments.
- Authors:
- Shelton, H. M.
- Radrizzani, A.
- Kirchhof, G.
- Dalzell, S. A.
- Source: Crop and Pasture Science
- Volume: 62
- Issue: 4
- Year: 2011
- Summary: Soil organic carbon (OC) and total nitrogen (TN) accumulation in the top 0–0.15 m of leucaena–grass pastures were compared with native pastures and with continuously cropped land. OC and TN levels were highest under long-term leucaena–grass pasture (P < 0.05). For leucaena–grass pastures that had been established for 20, 31, and 38 years, OC accumulated at rates that exceeded those of the adjacent native grass pasture by 267, 140, and 79 kg/ha.year, respectively, while TN accumulated at rates that exceeded those of the native grass pastures by 16.7, 10.8, and 14.0 kg/ha.year, respectively. At a site where 14-year-old leucaena–grass pasture was adjacent to continuously cropped land, there were benefits in OC accumulation of 762 kg/ha.year and in TN accumulation of 61.9 kg/ha.year associated with the establishment of leucaena–grass pastures. Similar C : N ratios (range 12.7–14.5) of soil OC in leucaena and grass-only pastures indicated that plant-available N limited soil OC accumulation in pure grass swards. Higher OC accumulation occurred near leucaena hedgerows than in the middle of the inter-row in most leucaena–grass pastures.
Rates of C sequestration were compared with simple models of greenhouse gas (GHG) emissions from the grazed pastures. The amount of carbon dioxide equivalent (CO2-e) accumulated in additional topsoil OC of leucaena–grass pastures ≤20 years old offset estimates of the amount of CO2-e emitted in methane and nitrous oxide from beef cattle grazing these pastures, thus giving positive GHG balances. Less productive, aging leucaena pastures >20 years old had negative GHG balances; lower additional topsoil OC accumulation rates compared with native grass pastures failed to offset animal emissions
- Authors:
- Richards, A. E.
- Cook, G. D.
- Lynch, B. T.
- Source: Ecosystems
- Volume: 14
- Issue: 3
- Year: 2011