Conservation Agriculture Practices to Improve the Soil Water Management and Soil Carbon Storage in Mediterranean Rainfed Agro-Ecosystems

Abstract

Water is the most limiting natural resource in agro-ecosystems of arid and semi-arid environments. In this regard, many areas of Southern Europe and other countries with similar climatic characteristic are being affected by the climate change, and many efforts oriented to achieve the sustainability of agriculture are being developed. Water limitations are forcing to implement different strategies to improve the water usage in agriculture, with significant constraints for the case of rainfed systems, where the improvement of water management must be focused to those soil management systems able to increase the soil water holding capacity. Implementing conservation agriculture (CA) practices such as minimum tillage (MT), direct drilling (DD), or the use of cover crops in perennial systems allows to improve the soil water retention and the its disposal for the crop during the maximum evapotranspiration period. Additionally, CA not only implies management strategies focused to climate change adaptation but also mitigation, encouraging the role of soil as a carbon sink. This work summarizes the advantages of these strategies, focusing on the effects of DD versus conventional tillage (CT) in rainfed systems for annual crops in terms of soil water conservation and carbon storage. On overall, DD practices allow to retain more water in the soil profile, as in the first centimetres as in the deeper zones of soil profile, with a faster soil water depletion in CT plots Moreover, significant higher CO2 emissions are promoted in CT systems in comparison to DD, in which the soil acts as a potential carbon sink. In conclusion, CA practices can act with a double role: as mitigation and as adaptation strategies to climate change.