Qualidade do solo no cultivo de pessegueiro, sob sistemas de produção agrícola familiar convencional e agroecológico, em Pelotas – RS

Abstract

Soil is a fundamental natural resource. Maintaining or improving its quality is essential for a higher productivity, as well as to ensure environmental quality and, consequently, human, animal and plant health. This study aimed at assessing soil quality and organic carbon stocks in family farms that have been cultivating peach for 21 years, with agroecological management (P-AM), conventional management (P-CM) and native vegetation (NV), in Maciel Colony, in the State of Rio Grande do Sul, Brazil. Soil samples were collected from different soil depths (0-5; 5-10 and 10-20 cm) and relief positions (upper, middle and lower thirds). Soil quality assessment and soil quality indexing were done in three stages: firstly, we selected physical, chemical and biological indicators for a minimum data set through principal component analysis and Pearson’s correlation; the values of the indicators of the minimum data set were then transformed into scores (0 to 1) using score curves; finally, all indicator scores were integrated using weighted additive method in order to create a soil quality index. Five principal components with eigenvalues > 1 were selected through principal component analysis. The order of the soil quality index values was the following: NV (0,81) > P-AM (0,62) > P-CM (0,37), with a High (NV), a Medium (P-AM), and a Low (P-CM) classification. Soil aggregate stability was the indicator with highest general contribution in the soil quality index. Compared to P-CM soil, NV and P-AM soils presented significantly higher stocks and concentrations of soil organic carbon and total nitrogen throughout soil profile. In conclusion, P-AM showed better soil quality and higher organic carbon stocks than P-CM. The results also showed that P-AM values were similar to those recorded in NV.