Spatial variability of copper and manganese in Ultisol cultivated with sugarcane crop

Abstract

Copper and manganese are trace elements and they are absolutely essential for the normal healthy growth of plants. These elements play a part of several enzyme systems and other metabolic functions in the plants. In soils, copper and manganese, usually occur in low levels and the dynamics of them can be affected by pH, humidity, organic matter content and mineral fraction of soil. Therefore, variations in the soil chemical attributes can induce changes in the availability of micronutrients. The aim of this study was to evaluate the copper and manganese levels and its spatial variability in an Ultisol cultivated with sugarcane. The study was carried out in a 790 ha area in the surrounding of Capim, Paraíba State, Brazil. A 300 x 400 m grid was projected onto the experimental area. Soil samples were obtained at each grid point (65 points) from 0-30 cm depth. The data set was submitted to descriptive statistics, geostatistics and kriging analyses. The coefficient of variation indicated medium and high variability to copper and manganese, respectively. Moderate spatial dependence was observed to copper and strong spatial dependence to manganese. The copper and manganese levels corresponded, on the average, to 0.81 and 1.13 mg kg^-1, respectively. The geostatistics analysis allowed a description of copper and manganese levels which permitted the definition of site-specific management.