Conservation Agriculture – a Portuguese Case study

Abstract

This paper gives a glance about the conservation agriculture concept and the worldwide increase of agricultural area where this technique has been adopted. The main constraints to agricultural production in the Mediterranean region are discussed, highlighting the importance of conservation agriculture to mitigate them. Results of long term studies with this technique, in Portugal, showed an increase in organic matter, the improvement of aggregates stability and the continuity of biological porosity along the soil profile. These changes of soil properties are helping to overcame edaphic and climatic constrains under Mediterranean conditions. The saturated hydraulic conductivity is improved allowing a better drainage during wet winters, and together with higher soil cohesion the transitability of the soil is enhanced, allowing a correct timing of field operations like nitrogen top dressing and herbicides application. Nitrogen use efficiency is improved either by the timing of application and by the improvement of soil organic matter content. Soil productivity is also enhanced and the overall energy use efficiency is double when soil organic matter content is raised from 1 to 2% in the top 30 cm of the soil. Therefore, conservation agriculture is advantageous from the economic and environmental point of view contributing for the sustainability of rainfed agriculture.