Carbono orgánico total y estabilidad de agregados de suelos sometidos al uso intensivo de agricultura

Abstract

Management systems affect the quality of the soil, due to the influence of the quantity and quality of soil organic matter, which can affect soil aggregation state. The aim of this study was to verify the influence of total organic carbon (TOC) in soil aggregate stability. The soil management systems evaluated were: Forest, pasture with 35 years, production of grains (corn and soybean) over conventional seeding system prepare the ground (Ploughshare and level for 35 years) (SC) and direct seeding system rotation of corn (SDRM) for 20 years since 1991. Before 1991 the area was used for grain production on SC. This study was conducted in the city of Jaboticabal, state of São Paulo, Brazil with latitude 21 ° 14'S, longitude 48 ° 17'W, located at 595 m altitude. According to the Brazilian System of Soil Classification [1], the soil was classified as a Latossolo eutróferrico Vermelho, according to the USDA Soil taxonomy database [3], is an Oxisol (Rhodic eutrudox). Soil samples were collected in the litter of 0-0.1 m depth in each management 38 system, at random and with a hoe, taking 30 samples of soil, collected in the SDRM was in between the lines of crops and in the SC was before preparing the soil, which were analyzed weighted mean diameter (WMD) of water-stable aggregates based on the methodology of [2] and the amount of TOC using the procedures described by [4]. COT data and soil DMP were statistically analyzed and means were compared by t test, a 5% probability. Each land management situation was considered a random sample of size 30 (soil samples). Separately for each soil management situation, we performed Pearson correlation analysis (P <0.05) occurred between TOC and DMP. The present grazing system and DMP TOC values similar to forest soil, with this system that presented the highest values of TOC and DMP in relation to use systems with SDRM and SC. The SC system presented the lowest values of DMP and TOC. Significant and positive correlations were obtained between TOC and DMP in all dealings evaluated. Therefore, in this study, soil aggregation was governed mainly by soil TOC.