Variability in cotton fiber yield, fiber quality, and soil properties in a Southeastern Coastal Plain

To maximize profitability, cotton (Gossypium hirsutum L.) producers must attempt to control the quality of the crop while maximizing yield. The objective of this research was to measure the intrinsic variability present in cotton fiber yield and quality. The 0.5-ha experimental site was located in a producer's field (Norfolk-Coxville soil association) in Florence, SC, for 2 yr (1996 and 1997). Soil (0-20 cm) and fiber samples (1-m row) were collected from a regular grid (129.2 by 45.6 m, 7.6-m interval). Soil properties determined included soil moisture, soil texture, organic matter, pH, Ca, Mg, K, P, and Na. Fiber quality was estimated by the high-volume instrumentation method and the Advanced Fiber Information System. Fiber strength and elongation were also estimated by the stelometer procedure. All fiber and soils data were analyzed by both nonspatial statistics and geostatistical techniques. Distinct patterns of spatial correlation were observed in soils and fiber yield. These patterns were not equally evident in all fiber properties. Soil pH, soil P, and soil organic matter were correlated with fiber yield and a number of fiber properties, including micronAFIS, immature fiber fraction, fine fiber fraction, cross-sectional area, and micronaire. Factor analysis of soil properties identified four factors in 1996 and three in 1997. In both years, a Carolina bay factor and an exchangeable bases factor were obtained. These factors were not successfully related to fiber yield and quality. Kriged contour maps of soil properties provided useful indicators of fiber yield and quality variation.