Alternate Harvesting Systems and Cotton Quality

Abstract

ABSTRACT HARVESTING cotton with a brush stripper has made it possible to produce cotton in narrow rows which increases yields where environmental conditions limit plant size. Harvest methods were compared from 1981 to 1983 to determine if brush stripping would reduce fiber quality. Harvest conditions varied greatly among the four tests conducted over the three-year period. Averaged across tests, brush stripped seed cotton contained 27.8% total trash compared to 4.6 for spindle picked seed cotton. Harvest methods had similar seed cotton moisture percentages and classers grade when harvested under dry conditions but the brush stripper had much higher moisture levels and lower classers grade when harvested under wet conditions. Averaged across experiments the brush stripper had mean fiber length that was 0.4 mm shorter than spindle picked; 0.9% more short fibers; a fiber length C.V. that was 1.2% more than spindle harvested; and a uniformity ratio that was 0.9 units less than spindle harvested cotton. Fiber strength was not affected by harvest method. Micronaire was slightly lower for brush stripped seed cotton than spindle picked but still in the premium quality range. Respirable dust was closely associated with lint moisture percentage. The association was significant for both harvest methods but highest for brush stripped cotton (R2 = 0.77 and 0.93). Brush stripped cotton averaged 37% more neps than spindle picked cotton. Number of neps was closely associated with fine feeder trash percentage of brush stripped cotton (R2 = 0.53). Spinning potential index (SPI) was related to both fine wagon trash and feeder moisture percentage (R^ = 0.53). When moisture was increased, SPI increased with low trash, was rather constant at intermediate trash levels, but declined sharply at high trash levels. These studies conclude that some loss of quality is associated with brush stripped cotton compared to spindle picked cotton even under favorable harvest conditions. When harvested conditions are less than favorable or adverse the loss of quality is sufficient to limit the use of brush strippers in the San Joaquin Valley of California where emphasis is upon maintaining a reputation for premium quality fiber.