Long-term decomposition of sugarcane harvest residues in Sao Paulo state, Brazil

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• 作者：Caio Fortes^a ; ^{caiofortes_eagr@yahoo.com.br} ; ^{caio.fortes@bp.com} ; Paulo Cesar Ocheuze Trivelin^a ; ^{pcotrive@cena.usp.br} ; Andre Cesar Vitti^b ; ^{acvitti@apta.sp.gov.br}
• 关键词：15N ; Straw ; C ; N ratio ; Cellulose ; Reduced tillage ; Litter bags
• 刊名：Biomass and Bioenergy
• 出版年：2012
• 期刊代码：3_09619534
• 类别：pw
• 出版时间：July, 2012
• 卷：42
• 期：Complete
• 页码：189-198
• 文件大小：664 K

摘要

Crop residues returned to the soil are important to preserve fertility and sustainability. This research addressed the long-term decomposition of sugarcane post-harvest residues (trash) under reduced tillage, therefore field renewal was performed with herbicide followed by subsoiling and ratoons were deprived of interrow scarification. The trial was conducted in the northern Sao Paulo State, Brazil during four consecutive crops (2005-2008) where litter bags containing ¹⁵N-labeled trash were disposed in the field attempting to simulate two distinct situations: the previous crop trash (PCT) or residues incorporated in the field after tillage, and post-harvest trash (PHT) or the remains of plant-cane harvest. Decomposition rates regarding dry matter (DM), carbon (C), root growth, plant nutrients (N, P, K, Ca, Mg and聽S), lignin (LIG) cellulose (CEL) and hemicellulose (HCEL) contents were assessed for PCT (2005聽ndash;2008) and for PHT (2006-2008). There were significant reductions on DM and C:N ratio due to C losses and root growth within the litter bags over time. The DM from PCT and PHT decreased 96%and 73%after four and three crops, respectively, and the higher nutrients release were found for K, Ca and N. The LIG, CEL and HCEL concentrations in PCT decreased 60%, 29%, 70%after four crops and 47%, 35%, 70%from PHT after three crops, respectively. Trash decomposition was driven mainly by residues biochemical composition, root growth within the trash blanket and the climatic conditions during the crop cycles.