Integration of Cover Crop Residues, Conservation Tillage and Herbicides for Weed Management in Corn, Cotton, Peanut, and Tomato
Type of Degreedissertation
DepartmentAgronomy and Soils
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Reduced water and air quality coupled with declining soil productivity and increased energy costs are the greatest concerns of present day agricultural producers and environmentalists alike. This generates the need of developing new production systems to achieve the twin objectives of profitability and environmental quality. Use of conservation tillage systems and cover crops can overcome many of these concerns by reducing production costs and maintaining the soil quality. However, predictability of weed suppression provided by these systems continues to be unpredictable. In current agronomic systems, where many weeds have acquired resistance or have proliferated within continually utilized crop technology, weed suppression through conservation tillage and cover crops offer a promising solution. Therefore, the objectives of this dissertation were to (a) develop a model that recommends dates for planting and terminating cover crops for optimum growth and weed suppression in conservation-tillage cotton and corn, (b) evaluation of weed suppression provided by a high residue rye cover in strip-tilled peanut, and (c) evaluation of cover crops for weed suppression in conservation-tillage tomato. In the first study, five seeding dates and four termination dates were evaluated for cover crop biomass production and its effect on weed suppression and yield in corn and cotton rotation. Results showed biomass production by winter covers was impacted with even a week’s delay in winter cover crop seeding and corresponding reduction in summer annual weed suppression. A second study was conducted at Dawson, GA and at Headland, AL. In this study strip tillage provided increased weed control in 2005 at Headland and equivalent control at all other site years. Furthermore, peanut yield was greater in three of the four site years utilizing strip tillage system indicating a yield advantage for utilizing strip vs. conventional tillage. The third study was conducted at Cullman, AL and at Tuskegee, AL. In this study we evaluated the short term effects of converting from a conventional plastic mulch system of growing tomato to three high-residue conservation tillage systems. Results of this study indicate the economic possibility of growing fresh market tomato utilizing a conservation tillage system while maintaining yields and economic returns.