Reduction of Soil Compaction in a Cotton and Peanut Rotation Using Conservation Systems
Simoes, Rui Pedro
Type of DegreeThesis
DepartmentAgronomy and Soils
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Southern Coastal plain soils have a long history of intensive continuous monoculture cropping, and are highly weathered due to geoclimatic conditions. These soils pose a challenge to the adoption of conservation agriculture due to subsoil compaction (densification of subsurface layers). This problem is usually addressed with adoption of non-inversion deep tillage. However, with ever-increasing prices of fuel this operation is often questioned by farm managers as too costly. Another problem facing farmers in this region is the lack of a good rotation system. In recent years, rotations of cotton (Gossypium hirsutum L.) and peanuts (Arachis hypogaea L.) have increased substantially in Southern Coastal plain due to reduced disease pressure and increased economic benefits provided by this rotation. Nevertheless many farmers are skeptical about adopting conservation tillage practices for peanut production due to fear of depressed yields caused by pests and diseases. We attempted to develop a conservation tillage system that included several methods of subsoil disruption. Three subsoiling implements were evaluated against a non-subsoiled treatment with and without a rye (Secale cereale L.) cover crop on a 4-yr cotton/peanut rotation at the Wiregrass Research Station in Headland, AL on a Dothan loamy sand (fine loamy, kaolinitic, thermic Plinthic Kandiudult). Plant, soil, and machinery parameters were evaluated: crop yield, cover crop biomass, cotton leaf temperature, soil moisture, bulk density, cone index, total soil carbon and nitrogen, saturated hydraulic conductivity, and tillage energy. Results showed consistently lower yields for non-subsoiled (11 and 51% lower, for peanuts and cotton, respectively) treatments. In one year of the study which was dramatically affected by drought, a cover crop provided a 26% increase in seed cotton yield. No differences between implements were found. Soil strength was greatly reduced by in-row subsoiling. During the 2006 cotton season, the no-till treatment had cone index of 3.6 MPa at the 10 cm depth which was significantly greater than any of the other in-row subsoiling treatments; Strip-till (0.9MPa), Paratill (1.4 MPa), and Worksaver (1.2 MPa). Our yield and economic results demonstrate that it is highly recommendable to in-row subsoil and plant a winter cover crop as they significantly boost productivity to competitive levels, increase net economic return, and improve system sustainability.