MEASURING THE SPATIAL VARIABILITIES OF COTTON FIBER PROPERTIES

Authors: Sassenrath, Gretchen; Williford, Julius; PRINGLE, H - DREC

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/10/2004
Publication Date: 6/1/2004
Citation: Sassenrath Cole, G.F., Williford, J.R., Pringle, H.C. 2004. Measuring the spatial variabilities of cotton fiber properties. 2004 Proceedings,Beltwide Cotton Conference. National Cotton Council, Memphis, TN. CD-ROM, pg. 2312-2317.

Interpretive Summary: Recent advances in engineering systems have allowed collection of spatially referenced yield within cotton production fields. The knowledge gained from these cotton yield monitors has contributed to our understanding of factors limiting cotton growth and production. While yield is a primary consideration in the economic return of a crop, for cotton, the quality of the lint determines the price paid for the crop. Detrimental growth conditions can significantly reduce the quality of the cotton lint, and the resulting price paid for the crop. Previously, no method was available that allowed consistent spatially referenced sampling of the cotton lint. We have developed a cotton sampler that attaches to the picker chute and samples the cotton during the harvest. Because the cotton is machine harvested, variations in lint properties from handpicking are eliminated. The cotton sampler allows us to develop spatial maps of all fiber properties. Using the sampler, we have determined the spatial variability of fiber properties, and the resultant spatial patterns of lint discounts. The overall lint discounts are linked with the yield to determine cotton profitability. Taking into account the management inputs, spatial maps of cotton profit margin are developed. These maps are then used to develop management scenarios based on optimizing profitability.

Technical Abstract: Development of spatial technologies, in particular yield-monitoring systems, has greatly enhanced our appreciation for the extent of spatial divergence in cotton production fields. Given the importance of fiber quality in determining the value of the cotton, there is considerable interest in understanding the spatial variability of cotton fiber properties, and its dependence on underlying field variability. Previous work has relied on hand harvesting of the cotton at intervals throughout the field, and measuring the fiber properties of the harvested lint. While this approach may be suitable for research plots or small-scale production fields, it is not amenable to full-scale production research. Moreover, the hand-harvested cotton has different fiber properties than cotton from the same area that is machine harvested. Both the harvesting and ginning methods alter the cotton fiber, and introduce deviations from the fiber qualities that would be measured by producers. We have developed a system of fiber sampling that removes a portion of the cotton during machine picking. These cotton samples are then ginned in a small research gin, and classed at the USDA-AMS Classing Office. Spatially registered maps are built of the various fiber qualities. Discounts based on the fiber properties and total lint discount are determined according to the Spot Cotton Quotations. Spatially registered maps of fiber discounts are also developed. Fiber value maps are combined with cotton yield and management inputs to determine spatially registered cotton profitability. Management scenarios that optimize profitability are then built for each of the discrete management zones as identified by the response of cotton growth, yield, fiber properties, and profitability.