|DOWNER, ROBERT - Louisiana State University|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2002
Publication Date: 12/20/2002
Citation: Johnson, R.M., Downer, R.G., Bradow, J.M., Bauer, P.J., Sadler, E.J. 2002. Variability in cotton fiber yield, fiber quality, and soil properties in a southeastern coastal plain. Agronomy Journal. 94:1305-1316.
Interpretive Summary: A cotton producer wishing to improve profits must attempt to control both fiber quality and yield, Precision agriculture has particular potential for increasing profitability while decreasing costly variations in fiber quality, variations that decrease both the price paid to the producer and the cost of processing the fiber at the mill. In this study, soil analyses, an important tool in precision agriculture, was combined with fiber quality quantitation to map the correlations among soil fertility and water content, cotton fiber shape and maturity, and yield. Distinct relationships were found between soil properties and yield. The yield correlations were particularly significant with respect to soil pH, soil phosphorus, and soil organic matter; and those soil properties were also strongly linked to fiber maturity and micronaire, an estimate of fiber maturity and thickness. The precision agriculture maps were particularly useful in describing the effects of the Carolina Bay landforms characteristic of fields in the study region [coastal South Carolina]. Contour maps of soil properties also provided useful indicators for fiber yield and fiber property variability.
Technical Abstract: To maximize profitability, cotton (GossypiumhirsutumL.) 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 two years (1996 and 1997). Soil (0-20 cm) and fiber samples (1-m row) were collected from a regular grid (129.2 x 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 non-spatial 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 phosphorus, 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 was 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.