Author
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Richard Jr, Edward |
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Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only Publication Acceptance Date: 6/18/2004 Publication Date: 6/30/2004 Citation: Richard Jr, E.P. 2004. Johnsongrass effects on sugarcane growth and chopper harvester efficiency [abstract]. Journal of the American Society of Sugar Cane Technologists. 24:119. Interpretive Summary: Technical Abstract: The species of weed and the duration of its interference can have a dramatic impact on sugarcane stalk size, number, and maturity, and ultimately cane and sugar yields. Very little is known about the compounding effects harvested-weed residues may have on theoretically recoverable sugar (TRS) levels and sugar yields. The impact of light (1 plant/9 row feet (rf)), medium (1 plant/6 rf), and heavy (1 plant/3 rf) rhizome johnsongrass infestations at the start of the crop year on TRS levels and cane and sugar yields was determined in a plant-cane (2002) and subsequent first-ratoon (2003) crop of 'LCP 85-384' sugarcane chopper-harvested green or burnt. In the plant-cane crop, johnsongrass reduced stalk counts by 9% (light infestation), 11% (medium infestation), and 14% (heavy infestation) when compared to a weed-free check. Stalk height was not affected by the various johnsongrass infestation levels. Reductions in stalk counts associated with the various levels of johnsongrass interference in the plant-cane crop were not reflected as differences in cane yields at the P < 0.05 level, but cane yields were higher (20%) where the cane was burned prior to harvest. Fiber levels detected in the harvested plant-cane crop were not influenced by johnsongrass infestation levels regardless of whether the cane was harvested green or burnt, but fiber levels in the burnt cane were higher than in the green cane. Differences in fiber levels were not reflected as differences in TRS levels. As expected, sugar yields mirrored cane yields with sugar yields not being influenced by johnsongrass infestation level, but being higher where cane was burnt. In the first-ratoon crop, late season panicle counts of 32 400, 41 800, and 55 400 per acre were obtained for the light, medium, and heavy johnsongrass infestation levels, respectively. Stalk counts decreased by approximately 5% at each increasing johnsongrass level while stalk heights were essentially equivalent at all johnsongrass levels and 4% lower than the weed-free check. In 2003, cane yields were 6% higher when the cane was harvested burnt. In contrast to the plant-cane crop, cane yields reflected johnsongrass infestation level with yields decreasing 8 to 20% as the infestation level increased. Fiber levels in the harvested billets were similar regardless of johnsongrass infestation and whether cane was harvested green or burnt, but fiber levels were actually lowest at the highest johnsongrass infestation level. This did not translate into higher TRS levels when compared to the weed-free check. Sugar yields were also affected independently by johnsongrass infestation levels and burning. Burnt cane yielded more cane and sugar while sugar yield decreased form 8 to 26% as the johnsongrass infestation increased. Improved harvester/operator efficiency contributed to the higher yields in the burnt cane. In addition, higher cane yields and fiber levels in the burnt cane may be partially attributable to the presence of immature cane tops in the burnt cane. These tops were easily blown away under a green-cane harvesting scenario. Finally, the chopper harvester appears to be relatively effective in removing johnsongrass residues present at harvest in the standing cane even when the crop is harvested green. |
