Soil-Management Systems in the Olive Orchard and Influence on the Organic-Matter and Nutrient Contents

Soil-management systems (SMS) in olive orchards alter the physical-chemical properties of the soil. Currently, cover systems of diverse types of plants as well as of shredded pruning debris are being used both in traditional as well as ecological olive orchards. The plant remains (from the covers or the olive trees) are managed with herbicides or mowers and shredders. Sometimes, the material is left on the surface and sometimes buried. The olive orchard, with appropriate soil management could be considered a sink for atmospheric carbon. To assess this potentiality, it is necessary to ascertain the contents in organic carbon and other nutrients for different types of soils and management systems. In this way, various management recommendations could be established for the entire diversity of the olive orchards in Andalusia (S Spain) as well as for other areas of the Mediterranean. The aim of the present work was to determine the contents in soil organic carbon (SOC), nitrogen (N), and potassium (K) in olive orchards with 8 different soil-management systems and management of the different plant remains. For this, 5 orchards of conventional management and 3 organic were selected. The results show that the SOC, N, and K contents are directly related to the soil-management system and the handling of the remains. The SOC content declined in all cases in comparison with those registered in the forest floors studied near the olive orchards. However, the olive-orchard soils with plant covers of all types plus the addition of pruning debris augmented the SOC, N, and K contents in the soils studied with respect to those in orchards with conventional tillage.