Winter Cover and Tillage Influences on Coastal Plain Cotton Production

Abstract

Winter cover crops and conservation tillage can be used by southeastern Coastal Plain cotton (Gossypium hirsuturn L.) growers to meet soil erosion control requirements of the 1985 Food Security Act. Our objective was to determine whether these production practices influence cotton productivity and quality. The study was conducted on a Norfolk loamy sand soil (fine-loamy, siliceous, thermic Typic Kandiudult) near Florence, SC, in 1991 and 1992. Treatments were winter annual cover crops, tillage, and timing of cover crop incorporation or desiccation before cotton planting. Cover crop treatments were crimson clover (Tnfoliurn incurnatum L.), hairy vetch (Viciu villosu Roth.), rye (Secufe cereufe L.), and winter fallow. Tillage systems were conventional (annual disking and bedding with in-row subsoiling) and conservation (in-row subsoiling only). Soil strength was measured during the spring in the fallow plots in both tillage systems. Incorporation (conventional tillage) or desiccation (conservation tillage) of the winter cover was done 5 or 15 d before cotton planting. Winter legume dry matter production was e1800 lb/acre per yr. Rye dry matter production was approximately 2200 lb/acre per year. Soil and crop variables studied were not affected by timing of the cover crop incorporation or desiccation. Soil strength was lower in the top 12 in. with conventional tillage. In conservation tillage, soil strength was the same both years. Conservation tillage had lower lint yield than conventional tillage by 267 lb/acre following clover and by 259 lb/acre following vetch [LSD(0.05) = 221 lb/acre]. Within winter cover treatments following fallow and rye, tillage systems did not differ in yield, but lint yield for conservation tillage following rye was 292 lb/acre greater than yield for that tillage system following fallow. Fiber properties were not greatly influenced by tillage system or winter cover, but micronaire was 0.1 units lower for cotton following rye than cotton following legumes. Including a rye winter cover crop may better insure successful conversion to conservation tillage cotton production systems on Coastal Plain soils. Research Question Surface residues are important in conservation tillage systems. After cotton harvest, there are few residues for soil protection or improvement. Using winter annual cover crops to increase surface residues in conservation tillage cotton production has been proposed. Our objectives were to evaluate two legume and one cereal species as cover crops for a cotton conservation tillage production system and to determine if soil strength increased with time for continuous conservation tillage cotton produced without cover crops. Literature Summary Successful conservation tillage production of sorghum and soybean in the humid southeastern USA was dependent on doublecropping winter and summer crops to provide large amounts of residues. Since doublecropping cotton is economically risky in much of the region, winter annual cover crops can provide residues for a conservation tillage system. Cotton yields following winter cover crops in conservation tillage systems are somewhat dependent on cover crop species. Conservation tillage cotton following a rye winter cover crop yielded higher than conservation tillage cotton following fallow and the same as conventional tillage cotton. Fiber property data for conservation tillage cotton following cover crops are needed. Study Description A cotton conservation tillage system (in-row subsoiling only) was compared with conventional tillage for 2 yr on a Norfolk loamy sand soil at Florence, SC. Experimental design: Main plots: Winter covers of rye, vetch, crimson clover, and fallow. Sub plots: Conservation and conventional tillage. Sub-subplots: Winter covers desiccated or incorporated at 15 or 5 d before planting. Applied Questions Which cover crops produced the most residue? Rye was superior to the legumes for biomass production both years of the study. It provided about 2200 lb/acre of residues each year. Crimson clover and vetch yielded 1600 lb/acre or less each year, with the clover being about the same as winter weeds in 1991. Did conservation tillage increase soil strength? Two years of conservation tillage did not influence soil strength. Soil strength of the surface 12 in. in conservation tillage during the second spring was about the same as for the first year. Did cover crops and tillage systems affect cotton yield and fiber properties? Fiber properties were not substantially affected by either winter cover or tillage. With conventional tillage, lint yield was the same for all winter cover treatments (Fig. 1). With conservation tillage, cotton following rye had greater yield than cotton following the legumes and fallow winter covers. The results of this study suggest that when converting to a conservation tillage system for continuous cotton, using a rye winter cover crop may help production on these Coastal Plain soils. Figure 1Open in figure viewerPowerPoint Influence of winter cover and tillage on cotton lint yield at Florence, SC. Bars with common letters are not different by LSD (P = 0.05).