Implication of Gypsum Rates to Optimize Hydraulic Conductivity for Variable-Texture Saline-Sodic Soils Reclamation

Sodium (Na+) dominated soils reduce saturated hydraulic conductivity (K-s) by clay dispersion and plugging pores, while gypsum (CaSO4 center dot 2H(2)O) application counters these properties. However, variable retrieval of texturally different saline-sodic soils with gypsum at soil gypsum requirement (SGR) devised to define its quantity best suited to improve K-s, leach Na+ and salts. This study comprised loamy-sand (LS), sandy loam (SL), and clay loam (CL) soils with electrical conductivity of saturation extract (ECe) of similar to 8dSm(-1), sodium adsorption ratio (SAR) of similar to 44(mmolL(-1))(1/2) and exchangeable sodiumof similar to 41%, receiving no gypsum (G(0)), gypsum at 25% (G(25)), 50% (G(50)) and 75% (G(75)) of SGR. Soils packed in lysimeters were leached with low-carbonate water [EC at 039dSm(-1), SAR at 056(mmolL(-1))(1/2) and residual sodium carbonate at 015mmol(c)L(-1)]. It proved that a rise in gypsum rate amplified K-s of LS >> SL>CL. However, K-s of LS soil at G(25) and others at G(75) remained efficient for salts and Na+ removal. Retention of calcium with magnesium (Ca2++Mg2+) by LS and SL soils increased by G(50) and decreased in G(75), while in CL, it also increased with G(75). The enhanced Na+ leaching efficiency in LS soil with G(25) was envisaged by water stay for sufficient time to dissolve gypsum and exchange and leach out Na+. Overall, the superiority of gypsum for LS at G(25), SL at G(50) and CL at G(75) predicted cost-effective soil reclamation with a decrease in ECe and SAR below 097dSm(-1) and 592(mmolL(-1))(1/2), respectively. Copyright (c) 2015 John Wiley & Sons, Ltd.