Submitted to: Southern Conservation Tillage for Sustainable Agriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 9, 2001
Publication Date: July 9, 2001
Interpretive Summary: Soil erosion causes soil and land degradation that directly threatens sustainability of agricultural production. Soil erosion is affected by rainfall characteristics such as rainfall intensity and duration, and by soil and surface conditions such as surface residue cover and roughness. The later is largely determined by tillage operations and cropping systems. .The objectives of this study were to evaluate the impact of cropping and tillage systems on reduction of surface water runoff and soil erosion and to further determine seasonal patterns of water runoff and soil erosion for each management system. Conventional and conservation tillage and cropping systems based on winter wheat were established and monitored on instrumented 4-acre watersheds at El Reno, OK, from 1985 to 1994. No-till and conservation tillage systems, compared with conventional tillage, significantly reduced soil loss; however, the reduction on surface water runoff was less pronounced. Annual soil loss, which was proportional to the levels of tillage disturbance, was predominantly caused by a few heavy storms. For a particular tillage system, monthly soil loss peaked in the periods when surface cover was low and precipitation was relatively high. This study shows that no-till and conservation tillage systems are very effective in reducing soil erosion in the southern Great Plains, and adjustment of tillage operations and cropping systems according to climate conditions has great potential to control soil erosion and enhance efficient use of rainwater.
Technical Abstract: Soil erosion is a worldwide problem and a major cause of soil and land degradation in the semiarid and arid regions due to limited vegetation cover and extreme weather conditions. Soil erosion is affected by climate, topography, vegetation, soil properties, management practices, as well as their interactions. In particular, tillage practices and cropping systems, ,which affect surface cover, have a strong impact on soil erosion. The objective of this paper was to evaluate the impacts of cropping and tillage systems on soil loss and surface runoff under semiarid climate conditions at a small watershed scale. Five 4-acre watersheds, which had 3 to 4% slopes and similar silt loam soils, were left in native grass or planted into winter wheat (Triticum aestivum L.) under different tillage systems. Daily runoff and soil loss, measured with a H-flume and an automatic sediment sampler at the outlet of each watershed, were used in the analyses. Annual soil loss was predominantly caused by a few large storms and was proportional to the levels of tillage disturbance. For a given tillage system, monthly soil loss peaked in the periods when surface cover was low and precipitation was relative high. Overall results indicate that notill and reduced tillage systems are very effective in reducing soil erosion in this region, and adjustment of cropping and tillage systems according to predicted climate conditions has a great potential to control soil loss and increase efficient use of precipitation.