Long term evolution of agricultural cropping system under saline irrigation in Southern Italy

The growth of the world population is expected to increase in the next forty years to reach 9 billion people in 2050. This will result in a dramatic increase in demand for food with the consequence of generating a strong competition in the use of agricultural resources, especially soil and water that will be used in a more efficient and sustainable . Currently, agriculture uses 70 % of the water resource but to meet the population growth will be necessary to increase agricultural production by 30% or increased use of water for irrigation or improving its efficiency in terms of production. Moreover, whereas the ongoing climate change will have a major impact on the regular supply of water resource in vast areas of the planet to support agricultural production option will no longer be postponed to use water in agriculture also not good quality and saline waste. In this new scenario for some time now we are studying new cropping systems that use irrigation water with a high salt content, or using species with low water requirements. In the last 15 year several crop were tested in Southern Italy to know their sustainable use to saline irrigation, some typical of this area as pepper, and melon, some industrial crop as sunflower and hemp and more recently innovative crop as quinoa and amaranths. Irrigation with saline water (I1 treatment) resulted in values of electrical conductivity (Ece) in the surface layer of soil that has changed over the years in relation to rainfall and evapotranspiration. The lowest value (5 dS/m-1) was recorded in 1998 while the highest (about 10 dS/m-1) in 2013. In relation to electrical conductivity of the soil crops showed a very different behavior in both physiological and productive aspects. At low values of Ece crops that resulted well adapted to saline irrigation was sunflower that for its ability to limit transpiration and capacity to sustain a good cellular turgor maintained good photosynthetic performances. The production has been slightly reduced for sunflower (-15%) in I1 compared to the control treatment (I0). Sharp reduction was observed for hemp (-35%). The pepper and melon instead have had less adaptability to irrigation with saline water with strong reductions in production (-50% ) in the treatment I1. Among the more recently introduced innovative crops in the agricultural cropping system quinoa in the irrigated treatment T1 with high saline water (ECW dS/m-1 = 22) and in the presence of very high levels of Ece in the soil (9.8 dS/m-1) showed no loss of production, confirming its great adaptability to cultivation in marginal land.