Irrigation Recommendation for Water Saving and Salinity Control in Horticulture in the Semi-arid Lower Cheliff Plain (Algeria)

Abstract

Salinity and water deficit are two major issues for agricultural development in Algeria. The Lower Cheliff plain, northwestern Algeria, is, furthermore, characterised by semi-arid Mediterranean climate, and soils with high clay content. Our study area was a 4 ha farm located in Oued Rhiou and another 1 ha farm located in Ouarizane, both upstream in the Lower Cheliff plain, and irrigated with waters of different salinities: 1.8 and 5.5 dS m-1, respectively. The plots were equipped with drip irrigation and subsurface drainage systems. Farmer’s irrigation management of artichoke and melon were observed during the respective cropping seasons from September 2010 till June 2011, and from April till July 2011. The total irrigation amounts were, respectively, 364 mm and 240 mm, while the precipitations were 367 mm and 67 mm. The soil properties were determined in the entire rooting depths down to 80 cm for artichoke and 60 cm for melon. In addition to these, irrigation water composition, and crop development parameters were used to simulate soil salinity using the SALTIRSOIL_M model. Simulations and observations of soil pH, main ion concentrations and ECe showed reasonable agreements for June 2011. Next, the irrigation schedules that would have met the water needs of both crops, while simultaneously keeping soil salinity below harmful levels were estimated using the model. For the artichoke plot, a lower irrigation rate (290 mm yr-1) could have kept water deficit and soil salinity below their respective harmful thresholds. For the melon plot, on the contrary, a higher irrigation rate (480 mm yr-1) is able to neutralise the water deficit, though not completely the salinity stress would have been adequate. Farmers’ irrigation practices in the context of the climate, water quality and soil properties of the Lower Cheliff plain can be analysed and improved with the aid of soil salinity modelling.