THE POTENTIAL OF NO-TILL AND RESIDUE MANAGEMENT TO SEQUESTER

Abstract

Soil organic matter contents under Mediterranean climatic conditions frequently are low to very low, especially where extensive land use and thus low biomass production is predominant. Reducing tillage intensity and maintaining crop residues in the field are considered to be promising agricultural practices to counteract the decline in soil organic carbon. The objectives of this work were to study the combination of no-till and the use of different crops and amounts of residues and their management on the evolution of soil organic matter. In two trials, crops were established under no-till over 3 years using different levels of wheat straw and their management and one treatment with residues of chickpea. Initial and final soil organic matter contents were analysed. The results indicate that the higher the amount of residues returned to the field the higher the increase of soil organic matter. Maintenance of straw compared to in situ feeding enhances the build-up of soil organic matter. Chickpea as a low biomass producing crop with a low C/N ratio of its residues showed no positive effect in terms of soil organic matter improvement. The results suggest that the return of cereal residues instead of its removal or grazing in combination with no-till for crop establishment can contribute considerably to improve the low soil organic matter levels found in Mediterranean environments.