SPATIAL DYNAMICS OF SOIL SALINITY IN AN ARID PALMETREE CULTIVATION SYSTEM IN ALGERIAAbderraouf Benslama, Kamel Khanchoul, Fouzi Benbrahim, Sana Boubehziz, Faredj Chikhi, Mohamed Amine Abdennour, Mahmoud Tourki and Jose Navarro-Pedreño
Soil salinity is the first real threat of soil degradation in drylands. This degradation will affect agricultural yields and thus accelerate the phenomenon of desertification. This study consisted mainly in knowing the movement of salts after two periods in an irrigated agricultural palm tree oasis influenced by an arid climate. The objective of this study was to quantify and model seasonal changes and try to understand the movement of salts in the soil profile to establish a sustainable management of the agro systems. Physicochemical properties were analysed to determine the quality of the irrigation water showing that this is admissible. A systematic soil sampling was applied to collect 45 samples covering the entire study area at two depths A1 (0-30cm) and A2 (30-60cm) in May (M) and November (N). Ordinary Kriging geostatistical method was used to obtain maps of soil salinity and the variation between depths: ï (M1-M2), ï (N1-N2), and as a function of time: ï (M1-N1), ï (M2-N2). The efficiency of these models was evaluated by calculating the mean error ME and the root mean square error RMSE for all the maps. There was a movement of salts facilitated by the sandy texture of the soils. A tendency of salt accumulation on the surface due to the scarcity of vegetation cover and a high evaporation rate was noticed. An accumulation in depth (A2) was observed in the middle of the study area due to the density of the planted palm trees which ensures a good soil cover, limiting evaporation and favouring the salt leaching process. This research can provide a tool to implement an adequate crop management program in this or similar areas, considering the need of a good palmtree cover of the soil to minimize salt accumulation in the soil surface, creating a microclimate inside the oasis.