Sustainable management of agriculture water resources: from leaf physiology to dry-land ecosystem services

Arid and semi-arid lands are characterized by low and highly inter-annual variability in total annual precipitation. Furthermore, the onset of the rainy season is unpredictable and the length of the "dry season" varies from year to year. All these factors strongly limit primary productivity in these areas. Population growth and predicted climate change are expected to further exacerbate this problem. The consequences would be a reduction of usable arable land and land productivity, widespread ecosystem degradation and higher risk of desertification. Drylands cover over 40% of global land area, are home to 2.1 billion people and comprise over 44% of the world"s cultivated systems. Approximately 70% of drylands occur in developing countries, where the livelihoods of the populace depend upon the ecosystem services sustained by the land. There is a strong correlation between poverty, development and the health of the land. Drylands constitute the largest biome on our planet and their degradation influences both the climate system and atmospheric composition. Drylands are amongst the most fragile areas of the globe and are inherently vulnerable to the effects of poor resource management. Desertification is considered to be the last stage of persistent land degradation caused by a combination of biophysical and human factors. There is therefore an urgent need to adapt and promote techniques that, without requiring large infrastructure and investments, could counteract land degradation and water shortage, leading to a recovery of crop productivity. Innovative water management techniques that can mitigate the impact of different environmental factors on agricultural production are currently available. It is essential that these systems of water management in agriculture are sustainable.