Sugarcane Trash Management Effects on Growth, Development and Water Relations.

Sugar has been a key product for Brazilian politics and its economy since from the early colony times. Brazil is currently responsible for nearly a quarter (23%) of the world’s sugar production and 50% of exports. In the 2013-2014, approximately 9 million hectares of sugarcane were cropped, producing 659 million tons (Mt) of harvested cane, 38 Mt of sugar, and nearly 28 billion liters of bioethanol. The average farm yield has gradually been increasing, reaching 80 tons ha^-1, but has since decreased by around 12% after 2010. One of the reasons for such decrease is due to the expansion of sugarcane areas to drier and warmer regions where irrigation is needed for assuring minimum yield levels. Also, trash has been historically burnt in Brazil, but recently crops have being increasingly harvested green with trash retailed as blanket (GCTB) due to environmental restrictions, and because of the trash use as a feedstock for bioenergy. In this study we analyzed data obtained along four year-experiment (being one with no trash plant-cane and three with trash blanket ratoons) comparing two treatments: GCTB and the trash removal. Field measurements covered regular crop monitoring (fresh and dry mass, height, tillering, leaf area index, sucrose concentration), and crop water use was based on Bowen ratio evapotranspiration, sap flow and soil water content, among other environmental measurements. Data revealed the trash slowing the crop emergence and initial tillering, but lately resulting in higher biomass during two dry years. The last ratoon was remarkably wet with no-trash treatment showing higher yields. Values of crop evapotranspiration and the physiological implications are also discussed.