• Authors:
    • Walker, C.
    • Edis, R.
    • Li, H.
    • Chen, D.
    • Suter, H.
  • Source: Soil Solutions for a Changing World
  • Year: 2010
  • Authors:
    • Bryan, B. A.
    • King, D.
    • Wang, E.
  • Source: Global Change Biology Bioenergy
  • Volume: 2
  • Issue: 6
  • Year: 2010
  • Summary: First-generation biofuels are an existing, scalable form of renewable energy of the type urgently required to mitigate climate change. In this study, we assessed the potential benefits, costs, and trade-offs associated with biofuels agriculture to inform bioenergy policy. We assessed different climate change and carbon subsidy scenarios in an 11.9 million ha (5.48 million ha arable) region in southern Australia. We modeled the spatial distribution of agricultural production, full life-cycle net greenhouse gas (GHG) emissions and net energy, and economic profitability for both food agriculture (wheat, legumes, sheep rotation) and biofuels agriculture (wheat, canola rotation for ethanol/biodiesel production). The costs, benefits, and trade-offs associated with biofuels agriculture varied geographically, with climate change, and with the level of carbon subsidy. Below we describe the results in general and provide (in parentheses) illustrative results under historical mean climate and a carbon subsidy of A$20 t−1 CO2−e. Biofuels agriculture was more profitable over an extensive area (2.85 million ha) of the most productive arable land and produced large quantities of biofuels (1.7 GL yr−1). Biofuels agriculture substantially increased economic profit (145.8 million $A yr−1 or 30%), but had only a modest net GHG abatement (−2.57 million t CO2−e yr−1), and a negligible effect on net energy production (−0.11 PJ yr−1). However, food production was considerably reduced in terms of grain (−3.04 million t yr−1) and sheep meat (−1.89 million head yr−1). Wool fiber production was also substantially reduced (−23.19 kt yr−1). While biofuels agriculture can produce short-term benefits, it also has costs, and the vulnerability of biofuels to climatic warming and drying renders it a myopic strategy. Nonetheless, in some areas the profitability of biofuels agriculture is robust to variation in climate and level of carbon subsidy and these areas may form part of a long-term diversified mix of land-use solutions to climate change if trade-offs can be managed.
  • 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
  • Authors:
    • Meyer,C. P. (M.)
    • Kirstine, W.
    • Galbally, I.
    • Wang, Y. -P.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 9
  • Year: 2010
  • Authors:
    • Maraseni, T. N.
    • Cockfield, G.
    • Maroulis, J.
  • Source: The Journal of Agricultural Science
  • Volume: 148
  • Year: 2010
  • Authors:
    • Renouf, M. A.
    • Wegener, M. K.
    • Pagan, R. J.
  • Source: The International Journal of Life Cycle Assessment
  • Volume: 15
  • Issue: 9
  • Year: 2010
  • Authors:
    • Stahlman,P. W.
    • Vigil,M. F.
    • Benjamin,J. G.
    • Schlegel,A. J.
    • Stone,L. R.
    • Blanco-Canqui,H.
  • Source: Agronomy Journal
  • Volume: 102
  • Issue: 4
  • Year: 2010
  • Summary: Because of increased concerns over compaction in no-till (NT) soils, it is important to assess how continuous cropping systems influence risks of soil compaction across a range of soils and NT management systems. We quantified differences in maximum bulk density (BD max) and critical water content (CWC) by the Proctor test, field bulk density (rho b), and their relationships with soil organic carbon (SOC) concentration across three (>11 yr) cropping systems on a silty clay loam, silt loam, and loam in the central Great Plains. On the silty clay loam, BD max in sorghum [ Sorghum bicolor (L.) Moench]-fallow (SF) and winter wheat [ Triticum aestivum (L.)]-fallow (WF) was greater than in continuous wheat (WW) and continuous sorghum (SS) by 0.1 Mg m -3 in the 0- to 5-cm soil depth. On the loam, BD max in WF was greater than in W-corn ( Zea mays L.)-millet ( Panicum liliaceum L.) (WCM) by 0.24 Mg m -3 and perennial grass (GRASS) by 0.11 Mg m -3. On the silt loam, soil properties were unaffected by cropping systems. Elimination of fallowing increased the CWC by 10 to 25%. The rho b was greater in WF (1.52 Mg m -3) than in WW (1.16 Mg m -3) in the silty clay loam, while rho b under WF and WCF was greater than under WCM and GRASS in the loam for the 0- to 5-cm depth. The BD max and rho b decreased whereas CWC increased with an increase in SOC concentration in the 0- to 15-cm depth. Overall, continuous cropping systems in NT reduced near-surface maximum soil compaction primarily by increasing SOC concentration.
  • Authors:
    • Caesar-TonThat, T.
    • Wright, S. F.
    • Sainju, U. M.
    • Kolberg, R.
    • West, M.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a Changing World, Brisbane, Australia, 1-6 August 2010. Congress Symposium 2: Soil ecosystem services
  • Year: 2010
  • Summary: Lentil ( Lens culinaris Medikus CV. Indianhead) used to replace fallow in spring-wheat ( Triticum aestivum) rotation in the semi-arid Eastern Montana USA, may improve soil quality. We evaluate the 14 years influence of continuous wheat under no-tillage (WNT), fallow-wheat under conventional tillage (FCT) and no-tillage (FNT), lentil-wheat under tillage (LCT) and no-tillage (LNT) on soil formation and stability, and on the amount of immunoreactive easily-extractable glomalin (IREEG) and soil aggregating basidiomycete fungi in the 4.75-2.00, 2.00-1.00, 1.00-0.50, 0.50-0.25, and 0.25-0.00 mm aggregate-size classes, at 0-5 cm soil depth. The 4.75-2.00 mm aggregate proportion was higher in LNT than FNT and higher in LT than FT treatments and mean weight diameter (MWD) was higher when lentil was used to replace fallow under NT. No-till systems had higher glomalin and basidiomycete amount than CT in all aggregate-size classes and glomalin was higher in LNT than FNT in aggregate-size classes less than 0.50 mm. We conclude that residue input in NT systems triggers fungal populations which are involved in soil binding in aggregates, and that replacing fallow by lentil in spring wheat rotation in dryland seems to favor aggregate formation/stability under NT probably by increasing N fertility during the course of 14 years.
  • Authors:
    • Sessiz, A.
    • Malhi, S. S.
    • Gürsoy, S.
  • Source: Field Crops Research
  • Volume: 119
  • Issue: 2-3
  • Year: 2010
  • Summary: Grain yield and quality of winter wheat ( Triticum durum L.) are affected by several factors, and crop management has a very important role among them. A 3-year (from 2003-04 to 2005-06) field experiment under irrigation was carried out at Diyabakir in the South East Anatolia Region of Turkey to evaluate immediate effects of tillage and residue management systems after cotton ( Gossypium hirsutum L.) on grain yield and quality [thousand grain weight (TGW), test weight (TW), protein content (PC) and mini sedimentation (mini SDS)] of durum wheat, and correlations among these parameters. A split plot design with three replications was used, in which two residue management treatments [collecting and removing cotton stalks from plots ( SRem), and chopping and leaving of cotton stalks in plots ( SLev)] were main plots, and six tillage and/or wheat planting method combination treatments [moldboard plough+cultivator+broadcast seeding+cultivator as conventional tillage-I (CT-I), moldboard plough+cultivator+drill as conventional tillage-II (CT-II), chisel plough+cultivator+drill as vertical tillage (VT), two passes of disk harrow+drill as reduced tillage-I (RT-I), rotary tiller+drill as reduced tillage-II (RT-II), and no-till ridge planting (RP)] were sub-plots. The effect of cotton residue management on grain yield, TW, PC, mini SDS was not significant, but SRem (51.21 g) gave significantly higher TGW than SLev (50.63 g). Tillage and/or wheat planting method combination treatments had a significant effect on grain yield, TGW and TW, but did not significantly influence PC and mini SDS. Conventional tillage with broadcast seeding (CT-I) treatment produced the lowest wheat grain yield (5.395 Mg ha -1), while there were no significant differences in grain yield among the other five tillage treatments (yields ranged from 5.671 to 5.819 Mg ha -1). In spite of supplemental irrigations, the variability of weather conditions, particularly the amount and distribution of rainfall during the growing season, had a significant influence on wheat grain yield and quality parameters (TGW, TW, PC, mini SDS). Grain yield had a significant positive correlation with TGW, but it did not show any relationship with other grain quality parameters. In conclusion, the findings suggest that conventional tillage with broadcast seeding would be less effective in producing grain yield of wheat compared to other five tillage treatments with row planting, while management of the previous cotton stalks may not have any effect on yield and quality of wheat except TGW.
  • Authors:
    • Halvorson, A. D.
    • Grosso, S. J. del
    • Alluvione, F.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 2
  • Year: 2010
  • Summary: Nitrogen fertilization is essential for optimizing crop yields; however, it increases N 2O emissions. The study objective was to compare N 2O emissions resulting from application of commercially available enhanced-efficiency N fertilizers with emissions from conventional dry granular urea in irrigated cropping systems. Nitrous oxide emissions were monitored from corn ( Zea mays L.) based rotations receiving fertilizer rates of 246 kg N ha -1 when in corn, 56 kg N ha -1 when in dry bean ( Phaseolus vulgaris L.), and 157 kg N ha -1 when in barley ( Hordeum vulgare L. ssp. vulgare). Cropping systems included conventional-till continuous corn (CT-CC), no-till continuous corn (NT-CC), no-till corn-dry bean (NT-CDb), and no-till corn-barley (NT-CB). In the NT-CC and CT-CC systems, a controlled-release, polymer-coated urea (ESN) and dry granular urea were compared. In the NT-CDb and NT-CB rotations, a stabilized urea source (SuperU) was compared with urea. Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. Cumulative growing season N 2O emissions from urea and ESN application were not different under CT-CC, but ESN reduced N 2O emissions 49% compared with urea under NT-CC. Compared with urea, SuperU reduced N 2O emissions by 27% in dry bean and 54% in corn in the NT-CDb rotation and by 19% in barley and 51% in corn in the NT-CB rotation. This work shows that the use of no-till and enhanced-efficiency N fertilizers can potentially reduce N 2O emissions from irrigated systems.