Reclamation of Saline and Sodic Soil: Effect of Irrigation Water Quality and Gypsum application form

Soil salinization has a detrimental effect on plant growth and contributes to agricultural land degradation. The ionic composition of the soil is a significant indicator of soil health. The soluble and exchangeable cation affects the physio-chemical properties of the soil, which in turn determine the suitability of the soil for agricultural use. Currently, soil salinization is one of the major threats to the agricultural productivity of arable lands in many regions of the world. The soils in arid and semi-arid regions having low precipitation and high evaporation rates, like the Negev Desert in Israel, are especially prone to high salinization. Due to the scarcity of fresh water, marginal irrigation water sources such as brackish water in conjunction with surface or subsurface drip irrigation are used extensively in these regions. In the long term, such practices are unsustainable, as precipitation and irrigation are too low to leach the accumulated salts from the active root zone. Salinity and sodicity already existing in many soils of semi-arid and arid regions are further exacerbated by such practices and the continued use might render the land uncultivable. Hence developing a sustainable and economical reclamation regime for saline-sodic soil is essential, while considering the available irrigation water quality in these regions. The main objective of this study was to develop a viable reclamation strategy by using locally available water resources, like brackish water, treated wastewater, desalinated water, and distilled water as rain simulation, with/without soluble or solid gypsum as an amendment. We used flow-through soil column experiments to study the cation transport and exchange in saline-sodic soil from Kibbutz Revivim, Israel (drip irrigated with brackish water for three decades) with four different water qualities and soluble gypsum. The results showed the effect of different water qualities and soluble/solid gypsum on the saturated hydraulic conductivity (K_s) and dynamics of cation exchange and transport in the soil. The transport of the major cations Na⁺, Ca²⁺, Mg²⁺, K⁺, and the K_s of the soil will be presented and discussed.

Keywords: saline-sodic soil, soil reclamation, cation exchange, irrigation water quality, gypsum.