Quality indicators in subtropical soils of Formosa,Argentina: Changes for agriculturization process

The agriculturization process has been defined as the advance of annual crops in different environments, in competition with traditional land uses such as agriculture rotations with pastures. In Argentina and other countries agriculturization has different degrees of impact on natural resources. In the northeast region of the province of Formosa, Argentina, agriculturization includes deforestation (clear cutting, slash burning and plowing), technological improvements and changes in land use. Because of these alterations, it is necessary to define the state of the soil to evaluate its sustainability. This can be done by means of indicators, which are not universal; they differ according to the use, management and type of soils, weather conditions and ecosystems.The objectives of this paper are: (1) To identify quality indicators for subtropical Argiudolls and Hapludolls; (2) To determine which indicators related to organic matter are most affected during agriculturization.The changes produced in the Typic Hapludolls and Typic Argiudolls after 25 years of continuously using native forests, agriculture, fruit plantations and pastures were analyzed. These changes were in pH, electrical conductivity, total organic carbon, particulate organic carbon, total nitrogen, structural stability, hydraulic conductivity, respiration and dehydrogenase and urease and enzyme activity. Variables with significant differences between diverse uses were evaluated by multivariate methods, Principal Component Analysis, and Correlation Analysis. The results of this study showed that total organic carbon, particulate organic carbon, structural stability and dehydrogenase activity are the quality indicators most affected by agriculturization. All are related to organic matter.