Microbial influence on release of acetylene and ethylene from calcium carbide and its impact on nitrification inhibition

Incubation studies were conducted to evaluate the microbial influence on the release of acetylene (C2H2) and ethylene (C2H4) in soil amended with encapsulated calcium carbide (ECC) by using gas chromatography and monitoring C2H2 as nitrification inhibitor. The GC-FID analysis revealed that under non-sterilized conditions ECC produced 542.1 mumol of C2H2 per kg soil over a period of 60 days. Under sterilized conditions 796.5 mumol C2H2 per kg soil was produced over a period of 60 days. Under non-sterilized conditions C2H2 was reduced gradually to C2H4 over a period of time and 44.8 mumol of C2H4 were recorded on 6th day of the incubation, however, under sterilized conditions no C2H4 was observed. This implies that conversion of C2H2 to C2H4 is a strictly biological process as no C2H4 was detected under sterilized conditions. The second study revealed that oxidation of NH4+ was reduced by ECC and NH4+ - N concentration was greater (up to 82%) by the application of ECC. Similarly NO3 -N was 79% greater in 30 mg N alone compared with ECC.