Adoption of Conservation - Tillage Practices and Herbicide - Resistant Seed in Cotton Production

The Natural Resources Conservation Service (NRCS) defines conservation tillage as a tillage system that leaves enough crop residue to adequately protect the soil from erosion throughout the year. The percent of cover required varies by field according to soil type, slope, crop rotation, winter cover crops used and other factors (NRCS website). Conservation tillage in general and notill practices in particular have increased over the past few years (Figures 1 and 2). Yet, despite the apparent advantages of conservation tillage in reducing soil erosion, soil degradation, runoff, and in improving soil quality (Edwards, 1995; Sandretto, 1997), some farmers adopt no-till or minimum-till while others do not. The use of conservation-tillage (CT) practices may be even more important in cotton production than other row-crop production because of the minimal amount of residue left on the soil surface. Crop residues after planting average 3% for cotton compared with 29% for corn (US Department of Agriculture Economic Research Service [USDA ERS], 1997). Yet adoption of conservation tillage is lower for cotton than for other crops in the United States. Additionally, it has been suggested that the adoption of CT practices impacts the adoption of herbicide-resistant (HR)1 cotton and vice versa (Fawcett & Towery, 2005; Roberts, English, Gao, & Larson, 2006). Therefore, if CT practices impact HR cotton2 adoption, then those practices can indirectly reduce residual herbicide use and affect farm profits; and conversely, if HR cotton adoption impacts CT practices, then HR cotton adoption may indirectly reduce soil erosion (Marra, Pardey, & Alston, 2003) through provision of effective and inexpensive weed control (Carpenter & Gianessi, 1999; Fawcett & Towery, 2005). Broadly speaking, there are three reasons a study on conservation tillage in cotton is important. First, conservation tillage (either no-till or reduced-tillage practices) may reduce soil erosion caused by wind or water by maintaining crop residue on the soil surface (Harper, 1996), increasing water filtration and moisture retention, and reducing surface sediment, water runoff, and chemical runoff. This is especially important in cotton production where farmers make extensive use of fertilizers and chemicals. Second, with the use of HR or stacked-gene (SG) seed technology, CT practices indirectly reduce the use of residual herbicides and may