PERDA E RECUPERAÇÃO DE CARBONO NOS COMPARTIMENTOS DA MATÉRIA ORGÂNICA DO SOLO NOS SISTEMAS CONVENCIONAL E PLANTIO DIRETO

Abstract

In soils under native vegetation (NV), the carbon content (C) is in stable equilibrium due to additions of organic residues of C are equal losses by decomposition. The conversion of NV agricultural systems causes a sharp drop in soil C stocks especially when management is based on tillage and soil preparation for growing grain. The objective of this study was to evaluate: 1) changes in the compartments of soil organic matter due to conversion of NV in the agricultural area and the use of soil preparation and management system for grain production, 2) The resilience of soil C associated with the no tillage cropping systems. This study was conducted in long-term experiments and in two places: 1) experimental station of the Agronomic Institute of Paraná (IAPAR) Ponta Grossa-PR and called PG, 2) experimental station Foundation of Rio Verde, in Lucas do Rio Verde, Mato Grosso and called LRV. The experiment design at both sites consists of macro-plots with three repetitions. Soil sampling at both sites were at depths of 0-5, 5-10, 10-20, 20-40, 40-60, 60-80, 80-100 cm and held in September and October 2009 respectively. For the assessment of organic matter pools were analyzed for total organic carbon content (TOC), oxidizable organic carbon (C-OX), total carbon in polysaccharides (C-PT), organic carbon extracted with hot water (C-HW), carbon particulate organic (POC), mineral associated organic carbon with (MAOC) and recalcitrant carbon (C-R). After conversion of native vegetation to agricultural land, the average stock of C for 0-20 cm decreased from 92.0 Mg ha-1 from NV to 67.4 Mg ha-1 to CT and from 48.0 Mg ha-1 in NV to 33.8 Mg ha-1 on the CT, in PG and LRV, respectively, and affecting the labile SOC compartiments as a C-PT and C-AQ. In PG, the NT in the 0-20 cm layer was higher in 17.0 and 14.3 Mg C ha-1 over the CT and MT, whose annual rate of accumulation of C was 0.71 to 0.85 Mg C ha-1. In LRV, NT systems with high input C of POC recovery the and OCAM similar to the NV (0-20 cm).