Location: Sugarcane ResearchTitle: Green-cane harvested sugarcane crop residue decomposition as a function of temperature, soil moisture, and particle size Author
|Webber Iii, Charles|
Submitted to: Sugar Tech
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2017
Publication Date: 7/19/2018
Publication URL: http://handle.nal.usda.gov/10113/5935597
Citation: White Jr, P.M., Webber III, C.L. 2017. Green-cane harvested sugarcane crop residue decomposition as a function of temperature, soil moisture, and particle size. Sugar Tech. 20(5):497-508. https://doi.org/10.1007/s12355-017-0579-6.
DOI: https://doi.org/10.1007/s12355-017-0579-6 Interpretive Summary: Commercial sugarcane is grown on over 170,000 hectares in the state of Louisiana. In 2016, the sugar crop was worth $750 million US. Most sugarcane is harvested “green” as opposed to burning leafy material off standing stalks prior to cutting, or burning cut stalks heaped into rows prior to milling. Green-cane harvesting returns a substantial amount of leafy crop residue to the soil surface every year. In Louisiana, cool, wet winters and the crop residue left on the field delays the spring ratoon crop’s emergence by a week or more, and can potentially reduce the ratoon crop’s yield by 10%. However, the crop residue contains many nutrients that can improve soil health and productivity if the residue is decomposed into soil organic matter efficiently. Therefore, our objective was to evaluate how temperature, soil moisture, and particle size influence sugarcane crop residue decomposition rates. In laboratory experiments, we observed the crop residue decomposed rapidly when the temperature was greater than 22°C (72°F). Soil moisture was also important, but not as important as soil temperature. We found that the smaller pieces of crop residue decomposed more quickly, when compared to larger ones. Overall our results indicate that earlier cut cane fields have the best chance to decompose green-cane harvested residue by taking advantage of warmer Oct. temperatures, and that mowing or shredding the crop residue increases its decomposition as well.
Technical Abstract: Sugarcane, a complex hybrid of Saccharum species, is grown on over 170,000 ha in the state of Louisiana. In 2016, the crop was worth $750 million US. Green-cane harvest, widely used in sugarcane producing countries, deposits up to 20 Mg ha-1 of crop residue annually. Green cane harvesting of sugarcane is recognized to be a more sustainable management opportunity than burning residue, or standing or heaped stalks. In Louisiana, cool, wet winters coupled with the crop residue reduce ratoon yields by as much as 10% y-1. However, the residue represents an important opportunity to improve degraded, low soil organic matter soils to facilitate sustainable sugarcane production. Our objective was to evaluate how temperature, soil moisture, and particle size influence sugarcane residue decomposition rates. In laboratory experiments, we observed rapid residue C mineralization rates at temperatures of > 23°C across all soil moisture levels tested, and calculated the residue decomposed by 71-95% over the course of the 155 d experiment. Particle size also increased decomposition, with 61, 72, and 91% decomposition observed for the >2.0, 0.25-2.0, and <0.25 mm particle size fractions, respectively. The results indicate that earlier cut cane fields have the best chance to decompose green-cane harvested residue by taking advantage of warmer Oct. temperatures, and that shredding the residue further increases its susceptibility to microbial decomposition. Future experiments will couple field decomposition of residue in-situ as well as incorporation of residue C into SOM.