Soil metal concentrations after five years of pasture-tosugarcane conversion

Abstract

: Extensive pastures are commonly converted to sugarcane areas in Brazil. In soils cultivated with sugarcane, tillage and fertilization are management practices commonly carried out. Soil management practices alter the physical and chemical properties increasing or decreasing metal availability. The purpose of this study was to quantify soil metal concentrations during pasture-to-sugarcane conversion correlating these changes with physical and chemical properties. The results showed that the concentration of metals in soil samples occurred according to the following order Fe > Mn > Cr > Zn > Cu > Pb > Cd. Significant increases in soil metal concentrations due the sugarcane cultivation were observed to Cd and Cu. The soil physical and chemical properties presented correlations with soil metal concentrations. There was a strong relationship on inorganic fertilization to change in soil metal concentrations. The principal component analysis (PCA) explained 55.4% of the total data variance, separating factors in two groups that pointed to an influence of fertilization on metal grouping. Inorganic fertilizer application may input 1.06 g·ha –1 ·year –1 Cd. The Cd concentration ranged from 0.15 to 1.07 mg·kg –1 , representing addictions of 9.54 mg·ha –1 ·year –1 Cd in soil. The metal concentrations observed after five years of pasture-to-sugarcane conversion did not represent environmental risks since the concentrations remained below the Brazilian official determinations.