Evaluating Soil Electrical Conductivity for Soil-Specific Seeding Rates in Cotton.

Precision management of cotton production can increase profitability by decreasing inputs.  Reducing seeding rates in soils while maintaining production potential will decrease input costs and may improve lint quality in drought-stressed soils.  The overall objective of this project is to improve cotton production profitability by minimizing seeding rates, maintaining maximum yields, and improving lint quality potential in water-limited soils.  The site selected was the Texas A&M University IMPACT center, which is located in the Brazos River floodplain and thus, has high soil variability.  For the 2008 and 2009 growing seasons, 27 measurement locations were selected in production-sized, irrigated cotton fields and planted in DP164 RRFBGII (Round-Up Ready Flex, Bollgard II. The sites were selected based on soil electrical conductivity (EC_a) values (3 categories).  Three seeding rates (30,000; 40,000; and 50,000 seeds acre^-1) were established in each of the three EC categories with three replications. In 2009 an additional seeding rate was added, 20,000 seeds acre^-1, which also increased measurement sites to 36.  At each measurement location, soil texture, soil moisture (weekly), lint quantity and quality (HVI) were measured. An additional replication for each EC category and seeding rate was selected for lint quantity and quality (HVI) measurements.  In 2008, differences in overall lint yield were evident within the three EC categories alone.  Average lint yield also varied within the three EC categories as a function of the seeding rates, with the largest standard deviation occurring in the lowest EC category.  The 2009 results will be presented as well.