Abstract

Liquid residue from pig farming contains nutrients that can be used for the fertilization of cultivated soils. The aim of this study was to evaluate chemical and microbiological changes in a sandy soil under pasture with Bermuda Grass (Cynodon spp) that received doses of pig liquid waste (PLW). The experiment was conducted in Cianorte-PR, Brazil, in a Typic Hapludox soil with sandy texture. The treatments consisted of 30, 60 and 90 m3 ha-1 yr-1 of PLW or chemical fertilizer (CF) applied for two years in a randomized block design, with three replications. Soil samples were taken at 0-10 cm, 10-20 cm and 20-40 cm layers, after three months of the second consecutive application of PLW in the second year, before grazing. PLW increased the concentrations of P, C and K at 10-20 and 20-40 cm soil depth, in addition to increasing the microbial biomass carbon and nitrogen and the population of rhizobia at 0-10 cm, in the treatment with 90 m3 ha-1 yr-1. PLW improved the chemical fertility at deeper soil layers and the biological fertility at 0-10 cm of a sandy soil under pasture.

Key words: Microbial biomass, organic fertilizer, phosphorus, potassium, rhizobia.