Matéria orgânica e formas de alumínio em um latosssolo vermelho distroférrico sob sistema plantio direto consolidado

Abstract

Savannah Cultivated soils possess chemical, physical and biological limitations, that associated to climatic factors contribute to its impoverishment, and so, for the soil quality deterioration. The maintenance and accumulation of the organic matter of the soil has been the best alternative to revert this situation, resulting in production increase with economical and environmental sustainability. The objective of this work was to evaluate different fractions of the organic matter of the soil, and carbon nitrogen content in these compartments, in clayey distroferric red Latossol, in different rotations of cultures under no-tillage system. The soil samples were collected in 2009, in Experimental Farm of Federal University of Great Dourados - UFGD, in Dourados, Mato Grosso do Sul, Brazil. The experimental design was in randomized blocks with three replicates, and the treatments in a factorial 5x4, with five rotation cultures: 1 – veth+oat+turnip / soy / turnip / corn / veth+oat+turnip / soy, 2 - sunflower / soy / veth+oat+turnip / corn / sunflower / soy, 3 - oat / soy / sunflower / corn / oat / soy, 4 - ervilhaca+aveia / soy / brachiaria / corn / brachiaria / soy, 5 – veth / soy / turnip / corn / turnip / soy; and four depths of the soil: 0-5, 5-10, 10-15, 15-20 cm. Physical grain size fractionation was used for determination of the particulate organic matter, and carbon and nitrogen contents. The conclusion is that the carbon levels in the particulate organic matter (C-POM), its stock in the soil and the soil nitrogen levels is not influenced by the different culture rotation systems. The rotation system 4, provides higher levels and stock of total organic carbon (TOC), carbon associated to the minerals of the soil (C-MOM), and also a higher C/N relation total and associated to the minerals of the soil (MOM). The levels of TOC, C-MOM, C-POM, total nitrogen (TN), nitrogen in the particulate organic matter (N-POM) and nitrogen in the mineral organic matter (N-MOM) are higher in the 0-5 cm depth.