Submitted to: Applied Engineering in Agriculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/2/2013
Publication Date: 6/15/2013
Citation: Wanjura, J.D., Boman, R.K., Kelley, M.S., Ashbrook, C.W., Faulkner, W.B., Holt, G.A., Pelletier, M.G. 2013. Evaluation of commercial cotton harvesting systems in the Southern High Plains. Applied Engineering in Agriculture. 29(3):321-332. Interpretive Summary: The stripper type harvester is the predominate machine used to harvest the Southern High Plains crop because it can more efficiently harvest low yielding cotton grown under dryland and limited irrigated conditions than a spindle picker harvester. However, interest in spindle pickers from Southern High Plains cotton growers has increased recently due to production practice changes leading to increased yields and improved fiber quality under irrigated conditions. The objective of this work was to compare yield, lint turnout, fiber quality, and agronomic parameters between stripper and picker based harvest systems on a large-scale commercial basis. The data collected are unique to all other studies in that the experimental units used in the analysis were full size seed cotton modules, each containing about 10 bales of lint. Thus, the findings of this work provide producers with a unique, scientific harvest system comparison on a full-scale commercial basis. Over the seven test sites utilized in the project, lint and seed yields were higher for the stripper based harvesting system by 96 and 104 lb per acre, respectively. Fiber quality was improved for picker harvested lint, but the increase in lint loan value was not adequate to offset lost revenue due to yield differences between harvest systems. Thus, the stripper based harvesting system returned $27 per acre more net revenue than the picker system across all test sites.
Technical Abstract: Cotton production practices have changed in the Southern High Plains of the US over the last decade resulting in increased yeilds and improved fiber quality. Moreover, the majority of US cotton now competes in a global fiber market that demands higher quality fiber for ring spun yarn than the former domestic open-end market. The brush-roll stripper harvester is the predominate machine used to harvest the Southern High Plains cotton crop, but interest in spindle pickers has increased recently in efforts to better preserve fiber quality, enhance profitability, and maintain the market share of US cotton in the global fiber market. This work was conducted to compare yeilds, fiber quality, and agronomic parameters between picker and stripper based harvest systems under commercial production and ginning conditions. Large-scale harvest system comparison tests were conducted at seven sub-surface drip irrigated sites across the Texas High Plains during the 2008-2010 crop years using brush-roll strippers with field cleaners and spindle pickers. Four cotton modules harvested from each site under each harvest method were ginned by a commercial gin. Compared to picker harvested cotton, stripper harvested cotton had 1096 kg/ha higher seed cotton yield which increased ginning charges by $72.40 per ha. Seed and lint yields were 217 and 108 kg/ha higher, respectively, for stripper harvested cotton resulting in $88.78 per ha higher total production revenue. Notwithstanding higher lint yield for the stripper system, custom harvesting was $51.38 per ha more expensive for the picker system due to the custom harvesting rates used (picking: $0.22 per lint kg; stripping: $0.18 per lint kg). Except for strength and reflectance that showed no difference by harvest method, all High Volume Instrument (HVI) fiber quality parameters were improved for picker harvested cotton. Due to improved HVI fiber quality and a substantial decrease in the number of bark contaminated bales, lint value was higher for picker harvested cotton. However, increased lint value was offset by decreased yield such that net revenue was $66.76 per ha higher for stripper harvested cotton across all sites.