Structural stability and hydraulic characteristics of soils irrigated for two decades with waters having residual alkalinity and its neutralization with gypsum and sulfuric acid

• Published in: Agricultural water management 2021-02, Vol.244, p.106609, Article 106609
• Main Authors: Minhas, Paramjit Singh, Bali, Aradhana, Bhardwaj, Ajay Kumar, Singh, Awtar, Yadav, Rajender Kumar
• Format: Article
• Language: English
• Subjects: Alkali water; Brackish water irrigation; Hydraulic properties; Infiltration characteristics; Soil sodification; Soil stability
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/j.agwat.2020.106609

Degradation of soils due to sodification is now widespread in arid and semiarid areas irrigated with groundwater having residual alkalinity. We monitored the changes in soil physical, chemical, and hydraulic characteristics of a sandy loam soil irrigated for the last two decades with two types of alkali waters (AW1, AW2) having similar salts (total electrolyte concentration, TEC=30 me L−1) and sodium adsorption ratio (SARiw 10 mmol L−1) but varying in residual sodium carbonate, RSC (5 me L−1 in AW1 and 10 me L−1 in AW2), and when latter irrigation water (AW2) was ameliorated to neutralize RSC equivalent to 5 me L−1 with either sulfuric acid (AW2 +SA) or gypsum (AW2 +GYP). Deterioration of overall soil quality was evidenced by increased bulk density and penetration resistance, decreased aggregate stability, increased soil pH and sodicity, and decline in accumulation of soil organic carbon, especially with AW2. Exchangeable sodium percentage (ESP) build up ranged between 2.1 and 3.3 times SARiw. The steady infiltration rate (IR) in soil irrigated with good quality water, GQW (Electrical conductivity, ECiw=0.52dSm−1; RSC=1.2 me L−1), was 5.4 mm h−1 (IR-GQW) while it reduced to 2.2, 1.0, 1.7, and 1.8 mm h−1 with AW1, AW2, AW2 +SA, and AW2 +GYP, respectively. The adverse effects of soil sodification exacerbated with rainwater (RW; simulated with deionized water, EC