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Implication of Gypsum Rates to Optimize Hydraulic Conductivity for Variable‐Texture Saline–Sodic Soils Reclamation
Author(s) -
Ahmad Sagheer,
Ghafoor Abdul,
Akhtar Muhammad E.,
Khan Muhammad Z.
Publication year - 2016
Publication title -
land degradation and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.403
H-Index - 81
eISSN - 1099-145X
pISSN - 1085-3278
DOI - 10.1002/ldr.2413
Subject(s) - gypsum , sodium adsorption ratio , loam , soil water , hydraulic conductivity , lysimeter , sodium carbonate , leaching (pedology) , chemistry , saturation (graph theory) , sodium , cation exchange capacity , soil science , mineralogy , geology , environmental chemistry , agronomy , irrigation , organic chemistry , paleontology , mathematics , drip irrigation , combinatorics , biology
Abstract Sodium (Na + ) dominated soils reduce saturated hydraulic conductivity ( K s ) by clay dispersion and plugging pores, while gypsum (CaSO 4 •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 (EC e ) of ~8 dS m −1 , sodium adsorption ratio (SAR) of ~44 (mmol L −1 ) 1/2 and exchangeable sodium of ~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 0·39 dS m −1 , SAR at 0·56 (mmol L −1 ) 1/2 and residual sodium carbonate at 0·15 mmol 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 (Ca 2+ + Mg 2+ ) 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 EC e and SAR below 0·97 dS m −1 and 5·92 (mmol L −1 ) 1/2 , respectively. Copyright © 2015 John Wiley & Sons, Ltd.