Municipal Solid Waste Compost: a potential amendment for saline-sodic soils

Abstract

Competing demands for the use of quality gypsum by other industrial sectors has necessitated the search for alternate amendments for sodic soils. Municipal Solid Waste Compost (MSWC) as conditioner has the potential for improving the physical, chemical and biological properties of the sodic soils. Considering these bene􀃶cial effects, the Hon'ble Supreme Court of India has also mandated the application of MSWC to maintain the soil health that may also ensure the safe disposal of this urban waste. Therefore, this study explored the potentiality of MSWC in the reclamation of saline-sodic soil irrigated with high SAR irrigation water. Conventional amendments gypsum (G) viz., GR25 (25% gypsum requirement), GR50 and its combination with -1 10 and 20 t ha of farmyard manure (F) and MSWC of Karnal (KC) and Delhi (DC) origin were incubated with soil for one month at 60% 􀃶eld capacity. After 30 days of incubation, a soil column leaching experiment was carried out with completely randomized factorial design in triplicate. Columns were sequentially leached up to ten pore volumes of synthetic saline −1 water having 􀃶xed EC of 6 dS m with variable SAR of 10 and 15 iw 1/2 −1/2 mmol L . Nature, quantity and independent integration of amendments had a positive in􀃸uence as evident from the decrease in soil alkalinity and leaching of salts. Unamended soil had high pH than amended soil. Leaching with saline water released an appreciable quantity of electrolytes from the soil. The + - 2- ionic balance analysis indicated an increase in Na , Cl , CO in 3 2+ 2+ + leachates with increase in SAR while contents of Ca , Mg , K , 2- - SO declined and that of HCO did not change. Leaching with 4 3 different SAR waters had considerable in􀃸uence on decrease in both pH and EC. Decrease in leachate pH was the maximum with the use of GR DC followed by GR DC and the least in control. 25 20 25 10 Changes in pH and EC showed inverse relation at different soil depths. Among the different combination of amendments, GR 25 -1 + DC (20 t ha ) treated soil showed greatest reduction in both soil pH and EC irrespective of water SAR.