Implementing Soil-Specific Seeding Rates to Increase Field-Scale Cotton Lint Quality

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 has the potential to 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 on a floodplain and thus, has high soil variability.  For the 2008 growing season, 27 measurement locations were selected in a 50 acre irrigated cotton field 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.  At each measurement location, soil texture, soil moisture (weekly), leaf area index (weekly), lint quantity and quality (HVI and AFIS) were measured. Additional replications for each EC category and seeding rate were selected for lint quantity and quality (HVI and AFIS) measurements.  The EC map responded to differences in soil texture and water holding capacities.  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.  Electrical conductivity maps of fields with variable soils may aid producers in making management practice decisions in the future, but field-scale experiments are needed for validation.  Variable rate technologies, such as varying seeding rates across a field with variable soils show promise, while fertilizer and irrigation applications could follow suit.  Electrical conductivity maps and variable rate seeding applications could eventually be implemented to precision harvest higher quality cotton bales.