Long-term application of swine manure can increase Cu and Zn contents in the pasture soils

Abstract

The intensive disposal of swine manure can promote accumulation of those low mobile nutrients in the soil surface, such as P, Cu and Zn, which can enhance their transference by runoff. The aim of this study was to evaluate the long-term effect of swine manure as fertilizer on chemical attributes of soil in pasture areas. Soil samples were collected from countryside areas in the southwest of Goiás state, where used swine manure as fertilizer from two breeding systems: Piglet production system (SPL) and finishing vertical system (SVT). The sandy and clayey soils received swine manure up to 10 years and over 10 years. Soil samples were also collected from native forest and permanent preservation areas as control. The samples were collected at 0-20cm, 20-40cm and 40-60cm depths to determine the contents of copper (Cu) and zinc (Zn), using Mehlich-1 as extractor. The t-test was used to evaluate the contrasts significance. The results showed that liquid swine manure of the SPL applied in sandy soils and the manure of the SVT in clayey soils for more than 10 years changed the contents of Cu in the soil up to 60 cm depth. Application of manure of the SPL in sandy soil affected Cu contents up to 60 cm depth. The liquid swine manure, continuously applied in clayey soils for up to 10 years did not modify the contents of Zn compared to the control soil.