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item Sassenrath, Gretchen
item Williford, Julius - Ray

Submitted to: American Society for Photogrammetry and Remote Sensing Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/15/2004
Publication Date: 10/25/2004
Citation: Sassenrath Cole, G.F., Williford, J.R. 2004. Determination of the spatial variability of cotton fiber quality and yield. American Society for Photogrammetry and Remote Sensing Proceedings. 2004 CDROM.

Interpretive Summary: Advances in engineering systems have greatly improved our knowledge of variability in crop production systems. In cotton production, the introduction of the yield monitor has improved our knowledge of within-field variability. Emphasis is being placed on discerning the underlying factors contributing to variability in yield within different regions of production fields. Ancillary measurements, such as soil and plant sampling, are performed during the growing season to develop correlations between measured yield at the end of the growing season, and plant growth conditions during the growing season. These measurements at times correlate well with observed patterns of yield variability, and with continuous measurements of field variability, such as remote sensing and electrical conductivity. While all of these measurements contribute in part to our understanding of the cropping system, they fail to completely determine the crop profitability. In cotton, the quality of the crop is an important determinant of value. The cotton is graded on a variety of factors, and the price determined as a result of those grades. To allow us to determine the spatial variability of the fiber quality, and calculate the value of the harvested cotton, we built a sampler that attaches to the cotton chute, and removes a sample of the cotton during the harvest operation. This cotton sample is then ginned and classed, for determination of a range of fiber properties, and final fiber value. In the research described here, we present the spatially registered cotton yield and quality measurements for a large research field. The cotton yield was found to be more highly correlated to soil characteristics (nutrient and texture) than was the cotton quality. The cotton quality had a direct and significant impact on the profitability, which has been observed to result more directly from yield components in other studies. The results indicate that cotton fiber quality is sensitive to a different array of factors than is the fiber yield. These factors need to be identified and considered when developing management scenarios for the various management zones, with an eye towards optimizing profitability.

Technical Abstract: The introduction of accurate, reliable cotton yield monitors has increased the value of spatial information pertaining to cotton (Gossypium hirsutum, L. sps.) growth and yield potential, and contributed to the development and incorporation of site-specific methodologies in cotton production. While this knowledge is important for developing precision management strategies, cotton quality also contributes to the profitability. Cotton fiber is graded for a variety of properties based on physiological maturity, from which the price is determined. Variability in cotton yield contributes to differences in profitability of various regions within fields. Variability in fiber quality will contribute additional alterations in the profitability of field regions. Currently, the determination of spatial patterns of fiber quality is performed by hand harvesting. However, hand harvesting is tedious, time consuming, and error prone. Hand-harvested cotton displays distinct differences in fiber properties from that harvested mechanically. Moreover, the time and labor commitment to adequately sample a large production field makes hand harvesting untenable for rapid and accurate determination of spatial patterns of fiber quality. Our research examines the spatial variability of fiber quality and quantity, with an end to delineating the underlying parameters contributing to that variability. To adequately address the variability of fiber production, we developed an accurate, rapid method of spatially sampling cotton lint as the cotton is mechanically harvested. The sampling system allows rapid subsampling of the harvested cotton in a spatially registered location. The analysis of the spatially registered cotton properties will be discussed in conjunction with its use in development of profitability maps and site-specific management.