Calcium Carbide-Based Formulations Cause Slow Release of Acetylene and Ethylene in Soil and Nitrification Inhibition

Nitrification inhibition (NI) of applied fertilizer nitrogen (N) is a suitable approach to improve N-use efficiency. Formulated calcium carbide (CaC2), a slow-release origin of acetylene, is a potent nitrification inhibitor; however, its efficacy in relation to different formulations has not been thoroughly investigated. In this study, seven CaC2 formulations viz. encapsulated; coated with beeswax, paraffin wax or paint, and matrix-I (21% CaC2, 58% polyethylene and 21% plaster of paris), matrix-II (42% CaC2, 48% polyethylene and 10% plaster of paris) and matrix-III (61% CaC2, 34% polyethylene and 5% paraffin oil) were incubated with soil and their effectiveness in acetylene and ethylene release and NI potential were compared up to 91 days. In CaC2 treatments, acetylene flux was decreased, whereas that of ethylene first increased and then decreased with time. During all the time intervals after day 7 of incubation, fluxes of acetylene and ethylene and NI were significantly greater with matrix I, followed by matrix II, paint-coated, and wax-coated CaC2. No acetylene release was noted with encapsulated or matrix III formulations after day 35 of incubation. Among other CaC2 formulations, matrix I, matrix II, and paint-coated CaC2 were better precursors of acetylene and ethylene, and nitrification inhibitors in the soil.