Dynamics and losses of soil organic matter and nutrients by water erosion in cover crop management systems in olive groves, in tropical regions

Abstract

Separation and transport of soil particles during an erosion event significantly reduce natural fertility of the soil and compromise the natural carbon dynamics of agricultural areas, especially in perennial crops of low plant density, as is the case of olive growing. This is a recently introduced crop in tropical regions in Brazil. Under Cwb climate conditions, characterized as a temperate rainy with a dry winter and a rainy summer, with an average annual rainfall of 1,411 mm, and average annual temperature of 19.3 °C, the aim of this study was to evaluate the dynamics and losses of soil organic matter and nutrients by water erosion in olive groves, under different management systems, in the municipality of Lavras, Minas Gerais state, Brazil. Five treatments involving the presence and absence of cover plants intercropped with olive trees were evaluated. The study of soil organic matter included determination of carbon, fractionation of soil organic matter (SOM) and of sediment and carbon management index (CMI). The results showed that maintaining spontaneous vegetation/weeds intercropped with the olive trees olive trees offered improved soil protection, mainly regarding carbon stocks, because it presented CMI increase from 20.91 up to 48.0 from non-conservationist to more conservationist olive cultivation and should, therefore, be adopted. Losses of nutrients and carbon where the olive tree is maintained without intercropping reached high levels, proving to be an unsustainable practice.