Soil Chemical Attributes under Agrosilvopastoral Systems and Pasture

Abstract

Agrosilvopastoral systems involve the consortium of trees, agricultural crops, and pasture, in the same area, concomitant or sequential, based on agroecological bases and on the cycling of organic matter and nutrients. This research compares soil fertility under pasture and agrosilvopastoral system. The area of 5 ha, is located on the Campus of the Federal University of Viçosa in Florestal city, central region of Minas Gerais state, formed by Urochloa decumbens for about 30 years, in an argisolic dystrophic Red Yellow Latosol. Two agrosilvopastoral systems - in single lines 2 x 10 m and double lines 2 x 2 + 10 m - were compared with pasture without trees. The soil preparation was conventional, with ploughing and leveling grids, in December 2009. Seedlings of the hybrid Eucalyptpus urophylla and E. grandis, clone GG100, were planted in level and subsoiler lines, which received 500 kg ha-1 of reactive phosphate at a depth of 0.5 m. At planting, each seedling received 120 g of N:P:K 10:28:06 + 0.3% B + 0.5% Zn; and 120 g of N:P:K 20:00:20, at 60 days. The corn was sown in the alleys, receiving 360 kg ha-1 of N:P:K 08:28:16 + 0.5% Zn, at planting, and 240 kg of urea ha-1, at 30 days. After the corn harvest, the pasture was formed naturally from the seed bank. At 135 months post-planting, five composite soil samples were collected in each studied area, obtained from ten simple samples of the 0-5 cm layer. The following attributes were analyzed: pH, P, K, Ca, Mg, Al, H + Al, OM, and Prem. The results were submitted to analysis of variance and F test (p,0.05), and the means of the significant treatments were compared by the Scott Knott test (p<0.05). Both APS provided an increase in the levels of OM, P, Ca, SB, t, and H + Al in the soil, keeping unchanged the other attributes analyzed in relation to conventional pasture. No significant differences in fertility were detected between the two agrosilvopastoral systems studied.