Monday, October 23, 2017: 9:50 AM
Marriott Tampa Waterside, Grand Ballroom B
The use of sugarcane harvest residues for the generation of electricity and second generation ethanol has been increasing in recent years as a strategy to increase the economic efficiency of the mills and in response to the growing demand for sustainable energy. However, the effects of straw removal on sugarcane yield, and the use of strategies such as legume break rotation to compensate them, are not well known. The objective of this study was to evaluate sugarcane yield under levels of straw removal in areas with and without legume break (Sunn hemp) rotation. The research was developed in four sites with contrasting soil and climatic conditions, located in Quirinópolis / GO (Site 1), Chapadão do Céu / GO (Site 2), Iracemápolis / SP (Site 3) and Quatá / SP (Site 4). I was used an experiment group structure, consisting of experiment with or without legume break rotation prior to sugarcane establishment. After cane-plant harvesting, the experimental design was a randomized block with four replications, where the plots received straw removal levels (0, 50 and 100%), which were evaluated in the first and second sugarcane ratoons. The tillering, SPAD index, foliar N content and stalk yield were evaluated. The effect of rotation on the tillering was restricted to the first ratoon, while the effect of the straw levels is more persistent on time and seems to be related to the temperature presented during the initial phases of crop growth and with the particular water regime of each site. The SPAD index and leaf N concentration did not present a clear trend as a function of the treatments. In one site, the increase in yield promoted by legume break rotation averaged 8.0 Mg/ha in the two years evaluated. In regions subject to water deficit, the reduction in yield caused by 100% straw removal ranged from 6.0 to 15.6 Mg/ha; however, removal of 50% of straw did not reduced yields in two sites evaluated. In the region with the lowest winter temperature, straw removal increased yield in 14 Mg/ha. Crop rotation did not compensate the effects of straw removal on sugarcane yield. The effect of straw removal for bioenergy purposes can be negative in locations susceptible to water deficit or positive in cold areas of the Brazilian sugarcane industry.