Chemical attributes of an Ultisol under different management systems in a humid tropical climate

Agricultural use of land normally changes soil properties, depending on soil management and climatic conditions. Aiming to analyze the chemical modifications of an Ultisol, this study was conducted to evaluate the soil chemical attributes when submitted to cassava planting and fallow condition and how it compares to the natural ecosystem in the region (Atlantic Forest). Soil samples were collected at depths of 0-0.20 and 0.20-0.40 m for chemical analysis of soil characterization. Most of the chemical attributes did not differ between the systems at any depth, with the exception of K in the cassava system with contents of 0.72 cmolc kg at the depth of 0-0.20 m and 0.57 cmolc kg at the depth of 0.20-0.40 m. The Atlantic Forest showed the highest values of P (34.61 mg kg) and total organic carbon (2.31 dag kg) at the depth of 0-0.20 m, which was significantly differing from the other systems. The period of 1 year fallow adopted to recover the productive capacity of the soil was not sufficient for the studied area. With the removal of the forests for implantation of the agricultural system (cassava) there was a marked reduction in the levels of organic carbon and phosphorus in the soil at the depth of 0-0.20 m. Key-words: Agricultural Land Use, Fallow Land, Cassava, Atlantic Forest