Qualidade da matéria orgânica do solo e estoques de carbono e nitrogênio em sistemas integrados de produção no norte de Minas Gerais

Abstract

The objective of this study was to evaluate the quality of the organic matter of an eutrophic Haplic Cambisol, after the implantation of silvopastoral systems in the North of Minas Gerais, in an area previously occupied by pasture of low productivity. The arrangement of the implanted systems consisted of integration of grass of marandu grass with Eucalipto cloeziana (SSP1) or urograndis (SSP2). These systems were compared with areas of regenerating stratum (ER) and native vegetation (VN). The design was completely randomized using subdivided plots to evaluate the physical-chemical and biological variables of the soil, and the factorial scheme 4X2 (four treatments and two epochs of evaluation) was adopted for efflux variables CO2 and flow H2O from soil (p<0,05). The carbon (C) and nitrogen (N) stocks of the soil increased in the SSP in relation to the RE, but were still lower in relation to the NP after four years of implantation. The chemical and granulometric fractionation indicated that carbon (C) was more stable in protected fractions of soil organic matter - MOS (humina and silt+clay). There was an increase in soil microbial carbon in the rainy season and the metabolic quotient in the dry period. The SSP1 increased microbial activity in the 10-20 cm layer of soil when compared to NR and ER, a result that can be attributed to the deposition of plant material and soil rotation for incorporation into subsurface in the cultivated system. The efflux CO2 was similar between VN and SSP2 in the rainy season and between SSP1 and VN in the dry period, which may indicate a greater diversity of organisms and roots in these systems in relation to ER. It can be concluded that the introduction of integrated systems improved soil quality when compared to ER, allowing greater protection of MOS.