Residues Decomposition In Crop Rotations Under No-Till System

The effectiveness soil cover in no-till is relating to quantity and quality of the phytomass produced by crops in rotation and, its persistence over the soil depends on residues decomposition. The objective of this study was to evaluate the phytomass production, decomposition rate and the half-life of crops in rotation at the Subtropical region, Brazil. The study was carried out at the Agronomic Institute of the Parana (IAPAR), in Ponta Grossa, Parana State, Brazil. The experimental design was randomized blocks, with six treatments and four replicates. Winter cash crops and cover crops, single and in consortium, were evaluated in the year 2014 (wheat, black oats + hairy vetch + rye, black oats + ryegrass and black oats + blue lupine), in 2015 (canola, black oats, and black oats + hairy vetch + forage turnip) and in 2016 (barley, triticale, and triticale + black oats + rye). The phytomass was evaluating by collect three subsamples of 0.25 m(2) per plot. For decomposition rate and the half-life of the crop residues, litter bags (LBs) methodology was used. A mathematical model (Q=Q(0)exp(-kt)) was used to represent the crop residues decomposition and the half-life of crop residues were obtained by the equation t(1/2) = (In2)/k. Poaceae consortia, single Poaceae and canola presented higher phytomass production when compared to Poaceae-Fabaceae consortia. The half-life for Poaceae-Fabaceae corsortia was shorter than single Poaceae.