Browsing by Author "Six, J."

Now showing 1 - 7 of 7
  • Aggregation and soil organic matter accumulation in cultivated and native grassland soils
    Six, J.; Elliott, E. T.; Paustian, Keith; Doran, J. W. (Soil Science Society of America, 1998)
    This study compares the impacts of no-tillage, conventional tillage, and native grasslands on three particulate organic matter (POM) fractions.
  • Carbon Sequestration in microaggregates of no-tillage soils with different clay mineralogy
    Denef, K.; Six, J.; Merckx, R.; Paustian, Keith (Soil Science Society of America, 2004)
    This study compares the soil organic carbon (SOC) sequestration of three different soil types under no-tillage and conventional tillage. In all three soil types, soils under no-tillage had greater total SOC and greater C in microaggregates. More than 90% of the difference in total SOC between no-tillage and conventional tillage was attributable to the difference in microaggregate-associated C, regardless of clay mineralogy differences.
  • Does the combined application of organic and mineral nutrient sources influence maize productivity? A meta-analysis
    Chivenge, P. P.; Vanlauwe, Bernard; Six, J. (Springer Netherlands, 2011)
    In Sub-Saharan Africa, soil quality declines as population pressures and low yields push the intensity of agricultural production upward. This meta-analysis offers a valuable insight on which external-input sources will have the most impact on Sub-Saharan African maize yields, nitrogen use efficiency, and soil organic carbon (SOC). Fifty-seven studies comprising 104 experimental sites in twelve countries (Benin, Burkina Faso, Cote d'Ivoire, Ethiopia, Ghana, Kenya, Malawi, Nigeria, Tanzania, Togo, Zambia, and Zimbabwe) were grouped according to the application of Organic Resources (OR), nitrogen fertilizers, and OR and N fertilizers. OR quality was further divided into four classes of decreasing qualities. Maize yields increased with increasing OR quality, both with and without N fertilizer application. Greater yield responses were seen with OR and N fertilizer application, however there is no evidence to suggest this was due to improved N use efficiency, as N use efficiency after combined applications was lower compared to N fertilizer application alone. SOC increase was observed in OR and OR and N fertilizer application, but not in N fertilizer application alone. These results suggest that nutrient storage increases with application of higher quality ORs and low levels of N may be added in conjunction with OR to achieve higher yield responses, but not to increase N use efficiency.
  • Long-term impact of reduced tillage and residue management on soil carbon stabilization: Implications for conservation agriculture on contrasting soils
    Chivenge, P. P.; Murwira, H. K.; Giller, Ken; Mapfumo, P.; Six, J. (Elsevier, 2007)
    The long-term effects of tillage system and residue management on soil organic carbon stabilization are studied in two tropical soils in Zimbabwe, a red clay and a sandy soil. The four tillage systems evaluated were conventional tillage (CT), mulch ripping (MR), clean ripping (CR) and tied ridging (TR). Soil organic carbon (SOC) content was measured for each size fraction as well as total SOC. Based on the findings, the authors conclude that residue management - maintaining carbon inputs - is most important for SOC stabilization in coarse-textured soils, whereas reducing tillage is the management priority for fine-textured soils.
  • Soil fauna and soil function in the fabric of the food web
    Brussaard, L.; Pulleman, M. M.; Ouédraogo, É.; Mando, A.; Six, J. (Elsevier, 2007)
    Through much research, the biological, biophysical, and biochemical interactions in soil are now understood much better. Tilling and fertilizing crop areas greatly affect decomposition and production processes, and hence the soil food web. By using a conceptual model to analyze the biophysical interactions, especially between soil fauna and soil structure, we can better understand the biological and biochemical processes in soil and their relation to the availability of water and nutrients to plants. This knowledge will help soil ecologists to increase the efficiency of crop production worldwide, reverse soil degradation and increase soil resilience.
  • Soil organic matter, biota and aggregation in temperate and tropical soils: Effects of no tillage
    Six, J.; Feller, C.; Denef, K.; Ogle, F. M.; de Moraes Sa, J. C.; Albrecht, A. (EDP Sciences, 2002)
    This article compares soil properties of temperate and tropical soils under no-tillage. The soil properties evaluated include soil C turnover rate, SOM quality, aggregate stability, total C levels, CH4 uptake, and N2O emissions.
  • Soil structure and soil organic matter: I. Distribution of aggregate size classes and aggregate associated carbon
    Six, J.; Paustian, Keith; Elliott, E. T.; Combrink, C. (Soil Science Society of America, 2000)
    This study compares aggregate size and carbon in three different soils, each with three tillage treatments (native vegetation (NV), no-tillage (NT), and conventional tillage (CT)).