• 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:
    • Herr, A.
    • Dunlop, M.
  • 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:
    • 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:
    • Rodriguez, L. C.
    • May, B.
    • Herr, A.
    • Farine, D.
    • O'Connell, D.
  • Source: Energy Policy
  • Volume: 39
  • Issue: 4
  • Year: 2011
  • Authors:
    • Booker, J.
    • Lascano, R.
    • Acosta-Martinez, V.
    • Calderon, F.
    • Zobeck, T.
    • Upchurch, D.
  • Source: Biology and Fertility of Soils
  • Volume: 47
  • Issue: 6
  • Year: 2011
  • Summary: In dryland agriculture in semiarid regions, crop establishment is not always possible because precipitation may not be sufficient. Modification of soil properties can improve the soil quality and functioning including soil water capture and storage capacity for crop production in dryland conditions. ARS scientists established a study near Lubbock, Texas in 2003 to compare the soil properties under different dryland cropping systems and tillage management. After only 3 years, this study detected increases in soil microbial community size and enzyme activities important for nutrient cycling under rotations with a winter cover crop such as cotton-rye-sorghum and haygrazer-rye compared to continuous cotton or sorghum-cotton at 0-10 cm soil depth. After 5 years, higher soil total C was found under Hay-Rye compared to the other systems. In addition, microbial properties were already impacted in all alternative systems (haygrazer-rye, cotton-rye-sorghum and cotton-sorghum) studied compared to continuous cotton. Several microbial properties indicative of increased soil water availability were also higher under the alternative rotations to continuous cotton. However, continuation of this study is vitally important for the long-term evaluation and confirmation of these trends, and their implications in water management, soil quality and crop productivity in dryland.
  • Authors:
    • Bird, M. I.
    • Beeton, R. J. S.
    • Menzies, N. W.
    • Witt, G. B.
    • Noel, M. V.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 141
  • Issue: 1-2
  • Year: 2011
  • Authors:
    • Blanco-Canqui, H.
    • Schlegel, A. J.
    • Heer, W. F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 144
  • Issue: 1
  • Year: 2011
  • Summary: No-till (NT) farming is considered as a potential strategy for sequestering C in the soil. Data on soil-profile distribution of C and related soil properties are, however, limited, particularly for semiarid regions. We assessed soil C pool and soil structural properties such as aggregate stability and strength to 1 m soil depth across three long-term (≥21 year) NT and conventional till (CT) experiments along a precipitation gradient in the central Great Plains of the USA. Tillage systems were in continuous winter wheat ( Triticum aestivum L.) on a loam at Hutchinson and winter wheat-sorghum [ Sorghum bicolor (L.) Moench]-fallow on silt loams at Hays and Tribune, Kansas. Mean annual precipitation was 889 mm for Hutchinson, 580 mm for Hays, and 440 mm for Tribune. Changes in profile distribution of soil properties were affected by differences in precipitations input among the three sites. At Hutchinson, NT had 1.8 times greater SOC pool than CT in the 0-2.5-cm depth, but CT had 1.5 times greater SOC pool in the 5-20-cm. At Hays, NT had 1.4 times greater SOC pool than CT in the 0-2.5-cm depth. Differences in summed SOC pool for the whole soil profile (0-1 m depth) between NT and CT were not significant at any site. The summed SOC pool with depth between NT and CT were only significant above the 5 cm depth at Hutchinson and 2.5 cm depth at Hays. At Hutchinson, NT stored 3.4 Mg ha -1 more SOC than CT above 5 cm depth. At Hays, NT stored 1.35 Mg ha -1 more SOC than CT above 2.5 cm depth. Moreover, NT management increased mean weight diameter of aggregates (MWDA) by 3 to 4 times for the 0-5-cm depth at Hutchinson and by 1.8 times for the 0-2.5-cm depth at Hays. It also reduced air-dry aggregate tensile strength (TS) for the 0-5-cm depth at Hutchinson and Hays and for the 0-2.5-cm depth at Tribune. The TS ( r=-0.73) and MWDA ( r=0.81) near the soil surface were more strongly correlated with SOC concentration at Hutchinson than at Hays and Tribune attributed to differences in precipitation input. Results suggested NT impacts on increasing SOC pool and improving soil structural properties decreased with a decrease in precipitation input. Changes in soil properties were larger at Hutchinson (880 mm of precipitation) than at Hays and Tribune (≤580 mm). While NT management did not increase SOC pool over CT for the whole soil profile, the greater near-surface accumulation of SOC in NT than in CT was critical to the improvement in soil structural properties. Overall, differences in precipitation input among soils appeared to be the dominant factor influencing NT impacts on soil-profile distribution of SOC and soil structural properties in this region.