Salinity evolution and crop response to secondary soil salinity in two agro-climatic zones in Lebanon

This paper reviews the human impact on land degradation through the integrated effect of fertilization and irrigation on secondary salinization for the different cropping patterns and agro-climatic zones of Lebanon. Agricultural operations in the semiarid northern areas of Lebanon are characterized by intensive open field and low tunnel production. Soil degradation has occurred because of the combined effect of mismanaged crop rotation, poor fertilization and irrigation policies. Monoculture and other agricultural practices caused salt accumulation in the soil (9.0 dS/m), which was then deserted after several years of exploitation. Under arid Mediterranean climate, these practices increased the vulnerability of an already fragile ecosystem. Because of water shortage, farmers relied on drip irrigation despite higher investment cost, although, the deterioration of soil quality was associated with the use of drip irrigation. The monitoring of soil quality indicated a self-recovery after several years of fallowing or a switch to a barley-based rotation. Instead of enhancing water use efficiency and properly managing the fertigation system, a replacement of drip by sprinklers is practiced. This is an indication that the introduction of modern irrigation systems is not sufficient, an improvement of agricultural practices and an upgrading of farmerʹs skills are required.