Influence of pyrite and farmyard manure on population dynamics of soil methanotroph and rice yield in saline rain-fed paddy field

Influence of farmyard manure (FYM) and pyrite application on methanotroph population and rice yield was examined during July 2008 to October 2008 in rain-fed saline paddy field using a rice variety namely HUR-3010. Four treatment plots with three replicates were established in completely randomized block design. The experimental design consisted of (a) control, (b) FYM, (c) pyrite, and (d) FYM + pyrite. Average methanotroph population was highest in FYM + pyrite treated plot (79.0 × 105 cells g−1 dry soil), and lowest in control plot (23.0 × 105 cells g−1 dry soil). Regression analysis exhibited negative relationship of methanotroph population with EC (R2 = −0.937) and NH4+–N (R2 = −0.892). Rice yield was highest in FYM + pyrite applied plots, while lowest in the control plot. Results suggested that the application of FYM and pyrite singly or in combination significantly enhance the number of soil methanotroph as well as rice yield in the saline paddy field.

Research highlights▶ This study demonstrates that FYM and pyrite application can enhance the population of methanotrophs in saline paddy soil. ▶ The long-term organic regimes can affect both the abundance and the composition of methanotrophs. Thus, the pyrite, crop residues and other organic amendments could be important strategies for enhancing the rice crop productivity, abundance and community composition of methanotroph in the alkaline paddy soils. ▶ The present experiment was conducted with the application of FYM and pyrite only, but the role of other organic amendments, green manures and microbial agents (blue green algae) in restoration and reclamation of salt affected paddy soils cannot be ignored as the organic amendments of saline soil is traditional practice in India.