Methane emission from rice–wheat cropping system in the Indo-Gangetic plain in relation to irrigation, farmyard manure and dicyandiamide application

Abstract

Methane (CH 4) is one of the important greenhouse gases accounting for 15% of the total enhanced greenhouse effect. Rice ( Oryza sativa L.)–wheat ( Triticum aestivum L.) cropping system is the most dominating cropping system in the Indo-Gangetic plains (IGPs) of India occupying 10.5 million ha of productive land could be a major source of atmospheric CH 4. Effect of irrigation, urea, farmyard manure (FYM), and dicyandiamide (DCD) on emission of CH 4 from an alluvial soil (Ustochrept) in rice–wheat cropping system was studied using the closed chamber technique. Total emission of CH 4 from the rice–wheat systems ranged from 16.2 kg ha −1 in the control treatment to 36.5 kg ha −1 in urea plus FYM treatment with an average emission of 20.8 kg CH 4 ha −1. Continuously saturated soil in rice gave higher CH 4 emission compared to intermittent wetting and drying soil condition but the yields were lowered. Application of DCD with urea reduced emission of CH 4 in rice–wheat system to 70%, while substituting 50% of inorganic N with FYM increased emission to 172% compared to application of entire amount of N through urea. In wheat negative fluxes of CH 4 up to 0.1 kg ha −1 per day was recorded. There was no difference in CH 4 flux in wheat between the various irrigation treatments. In the most common fertilizer practice in IGPs the emission of CH 4 is 21.2 kg ha −1. Intermittent wetting and drying of soil in rice has a potential to reduce the emission.