SOIL FERTILITY, GREENHOUSE GAS EMISSIONS AND AGRONOMIC PERFORMANCE IN A VINEYARD WITH DIFFERENT SOIL MANAGEMENT IN A SEMIARID MEDITERRANEAN ENVIRONMENT

In the semiarid Mediterranean environment, vineyard soils are often characterised by intensive tillage and large supply of inorganic fertilizers. Those practices, coupled with the semiarid Mediterranean climate features (warm to hot, dry summers and mild, wet winters),speed up the mineralisation of soil organic matter (SOM) so that many lands have lost much fertility. To counteract SOM decline, the introduction of cover crops with or without nitrogen (N) fixing forage legumes, has become a management technique widely used. Indeed, cover crops besides increasing SOM and potentially mineralisable N, it can mitigate soil erosion in sloping vineyards. However, the competition risk for soil water resources between the cover crop and the vineyard has markedly limited the adoption of this practice in semiarid environment. While some studies are available on the effects of soil tillage and cover crops on carbon and nitrogen dynamics in vineyard soils, only few studies have investigated their effects on CO2, N2O and NH3 emissions. On the one hand, tillage and cover crop may stimulate CO2 emissions by speeding up the mineralisation process via aggregate breakdown and by adding fresh organic residues, respectively. On the other hand, the addition of organic residues rich in nitrogen may contribute to N gases (N2O and NH3) release from soil. N2O emission from soil in semiarid environment are expected due to climatic conditions (rainfall concentrated in a short period) that can create, in clayey soil, anoxic microsites where denitrification can occur. Also NH3 emissions are expected due to the presence of calcareous soils. The aim of this research is to investigate the effect of different soil managements, namely tillage and cover crop, on emission of greenhouse gases (CO2, N2O, NH3) from a vineyard soil. Furthermore, soil fertility and agronomic performance of the vineyard will be evaluated to find out the best management practice.