Dynamics of soil organic matter and nutrient losses by water erosion in relation to management of plant covers in olive orchards in tropical regions

Abstract

Most soils have a large supply of plant nutrients and water, and soil carbon storage is a vital ecosystem service. Soil erosion from water can cause losses of nutrients and organic carbon, causing potential environmental degradation, especially in tropical regions where soils naturally present low fertility. The characteristics of the soil and the surrounding vegetation also influence the rate of erosion. In this respect, conservation practices can reduce losses and ensure the quality and productivity of soils. However, it is of great importance to know the behavior of each crop with respect to the protection that it promotes the soil against erosive agents in order to adequately elaborate the management plan of the area. Olivicultura is recent in tropical regions in South America and most studies on olive cultivation do not assess the impact of the crop on the soil, especially regarding the occurrence of erosion and nutrient and carbon losses in these areas. Thus, there is still a gap to be filled. In this context, the present study aimed to evaluate nutrient, carbon, and organic matter fractions in samples from an experimental plot of erosion and sediment cultivated with Olive (Olea europaea), in tropical regions. The experiment was conducted in the orchard of the Federal University of Lavras, south of Minas Gerais state, Brazil. The soil was classified as Cambisol and the treatments involved cover plants and spontaneous vegetation management, during three years of evaluation. After each rainy event, sediment samples were collected for laboratory analysis. Granulometric fractionation was applied to obtain particulate and complex organic matter, which are essential for determining the carbon management index (CMI). After digestion, macro and micronutrients were determined ICP-OES. The results showed that CMI is an adequate indicator of the quality of the applied management and the presence of spontaneous vegetation in the line is the best alternative to reduce losses of carbon and nutrients in olive cultivation.