Greenhouse gas emissions from rice based cropping systems: Economic and technologic challenges and opportunities.

Recent market slump in rice, less rainfall during monsoon, high temperature and scarcity of water during dry season leads to lower grain yield and less profit from rice cultivation in India. Farmers' grow upland crops like chickpea ( Cicer arietinum), greengram ( Vigna radiate), mustard ( Brassica nigra), corn ( Zea maize), pigeonpea ( Cajanus cajan), potato ( Solanum tuberosum), sunflower ( Helianthus annuus) etc. along with rice ( Oryza sativa) during the dry season. However, knowledge of greenhouse gas (GHG) emission from these rice based cropping systems is very limited. In the present study four rice based cropping systems was studied along with rice-rice rotation system as control in respect of GHG emission, yield potential and economic feasibility. Conventional plantation and fertilizer application methodology was followed for each crop. Methane (CH) and nitrous oxide (NO) flux from field plots were studied with conventional closed chamber method using gas chromatograph. CH flux was recorded highest from rice-rice rotation plots (304.25 kg ha). NO flux was recorded 1.02 kg ha from rice-rice rotation system during wet season. However, during wet season, higher NO flux (1.93 kg ha) was recorded from rice-potato-sesame rotation plots. Annual NO flux was also recorded significantly low (3.42 kg ha) from rice-rice rotation plots and high (6.19 kg ha) from rice-chickpea-greengram rotation plots. Significantly lower annual grain yield was recorded from rice-rice rotation plots (9.25 Mg ha) whereas it was 18.84 Mg rice eq ha from rice-potato-sesame rotation system. The global warming potential (GWP) of rice-rice rotation system was recorded significantly high (8.62 Mg CO ha) compare to plots with different rice based cropping systems. Computing all C-emission from cradle-to-grave, highest total C-cost was recorded from the rice-rice rotation system ($62.00 ha). We have made an attempt to calculate the C-credit of different rice based cropping systems by considering the difference of C-cost with control. The study suggests that the rice-potato-sesame is most sustainable among different cropping system studied in terms of economic profit ($1248.21 ha) and C-credit ($38.60 ha). The result of the study may be limited to the study region; however, the study has potential use in respect to the development of agriculture practice for adaptation to climate change. [ABSTRACT FROM AUTHOR]