EFFECTIVENESS OF CALCIUM CARBIDE FOR IMPROVING NUTRIENT USE EFFICIENCY AND YIELD OF WHEAT CROP

Abstract

Calcium carbide is well known as a nitrification inhibitor and its role as a source of ethylene (C2H4), a potent plant growth regulator, is not thoroughly investigated. Laboratory, pot and field studies were conducted, in a sequence, up to 4 years to evaluate the effectiveness of calcium carbide (CaC2) on nitrogen use efficiency, growth and yield of wheat. First and 2nd experiments were conducted to assess the best rate and time of application of encapsulated calcium carbide (ECC) regarding plant growth and yield parameters of wheat. It was found that ECC @ 22.5 mg kg-1 soil, applied 2 weeks after sowing performed the best of all other rates and times of application of ECC in improving economical yield of wheat. In the 3rd experiment CaC2 coated with bee wax, paraffin wax and black enamel paint and matrices (prepared with polyethylene) was used to slow release the gases. Release of acetylene and ethylene from these calcium carbide based formulations and their impact on nitrification process in the soil environment under laboratory conditions was studied. It was noted that matrix-I (containing 21 % CaC2) not only performed as the best and sustainable source of acetylene and ethylene in the soil but also inhibited nitrification process better than other formulations. Calcium carbide based formulations were also compared in pot studies regarding their effect on wheat seed germination and growth and yield parameters of wheat. Matrix-I benefited the wheat crop to the maximum, followed by matrix-II and paint coated calcium carbide. Two further pot experiments were conducted to know the best rate and application depth of matrix-I formulated calcium carbide with and with out nitrogen fertilizer application. It is evident from the results that matrix-I not only improved growth and yield parameters of wheat but also enhanced N uptake by different plant parts of wheat when applied @ 15 mg CaC2 kg-1 soil at 8 cm soil depth. It was further noted that matrix-I better improved N use efficiency when applied with half recommended dose of N fertilizer than that of with full recommended N fertilizer rate. Two years field experimentation confirmed the results of pot studies. Under field condition CaC2 based formulations not only improved wheat growth and yield parameters but also reduced lodging of a lodging susceptible wheat variety Bhakhar-2002. Overall results suggest that application of calcium carbide increased grain yield more than 30 % by improving yield contributing factors and N use efficiency.