Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1999
Publication Date: N/A
Interpretive Summary: A reduced tillage system of agriculture is necessary for the sustainability of highly erodible soils formed in loess deposits of the lower Mississippi River Valley. However, before a particular system is implemented, its ability to improve soil properties and the time required for such improvements should be determined. Data from this study showed that no-till produced 45% more organic matter than conventional tillage in the soil surface within four years of implementation. Other soil properties such as aggregate stability and water dispersible clay content did not change substantially until the length of study approached eight years. Apparently, for this soil type under these climatic condictions, a time period exceeding four years is required for substantial reduction in soil erodibility. Consequently, such studies should be conducted a minimum of eight years to adequately evaluate the system.
Technical Abstract: The time required for a given no-till management practice to affect a significant improvement in surface soil properties is an importantaspect in evaluating their suitability for sustaining soil resources in a productive state. The objective of this study was to determine the extent to which conservation tillage practices change soil erodibility and fertility-related properties of a representative soil from one of the most erosion prone regions in the United States. Conventional (CT) and no-tillage (NT) treatments were replicated 10 times on a Grenada silt loam using cotton, grain sorghum/corn, and soybean as test crops. Soil samples were collected at depths of 0 to 2.5, 2.5 to 7.6,and 7.6 to 15.2 cm at the beginning of the study, after four and eight yr. These samples were characterized for organic matter content (OM), pH, exchangeable Ca and Mg, extractable macronutrients, extractable micronutrients, aggregate stability (AS), water dispersible clay (WDC), modulus of rupture (MR), and clay content. The data indicate that OM was essentially the only chemical property affected by NT which produced significantly greater amounts in the 0 to 2.5 cm depth for all crops after four yr compared to initial levels. Relative to CT, NT OM was 45% greater after 4 yr and 47% greater after 8 yr, when averaged for all crops. During this time period, AS of the NT was 36% greater than CT after four yr and 50% greater after eight yr, whereas, WDC decreased an average of 22 and 47%, and MR decreased 52 and 70%, respectively. These results indicate that within four yr of implementing NT practices, significant increases can be expected in OM contents which enhance most other properties that determine soil susceptibility to erosion.