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Carbon dioxide (CO 2 ) efflux from soil is one of the very important components of global carbon cycle and climate change. Land use and climate are the major factors that influence the rate of CO 2 efflux. The present study was undertaken to evaluate the monthly variation in rate of CO 2 efflux and its correlation with soil temperature and soil moisture in agricultural lands under different crops and crop rotations in part of Indo-Gangetic plain in India. The Indo-Gangetic plain covers 13% geographical area of the country and produces 50% of the total food grain of the country. The agricultural lands are cultivated for variety of crops including, Oryza sativa (Paddy), Triticum aestivum (Wheat), Zea mays (Maize), Brassica herta (Mustard), Trifolium alexamdrinum (Barseem), Sorghum bicolor (Jowar), Sachharum officinarum (Sugarcane) and several pulses and vegetables. The average annual CO 2 emission rate ranged between 0.56 g m -2 h -1 (wheat -fallow-paddy) and 0.75 g m -2 h -1 (jowar-barseem) with a mean value of 0.64 g m -2 h -1 . The standard deviation varied from 0.06 to 0.25 and the standard error varied from 0.02 to 0.03. Wheat crop combinations (wheat-fallow-paddy, wheat-fallow, wheat-maize, wheat-pulses, wheat-sugarcane, wheat-jowar, and wheat-vegetable) showed relatively lower values of average annual CO 2 emission rate whereas highest emission rates were found in vegetable crops. During monsoon months the rate of CO 2 emission from soil was higher due to favorable moisture and temperature conditions, while in winter the same was observed minimum in all the crops. The study leads to infer that crop, crop rotation and soil temperature and moisture have significant effect on soil CO 2 emission.

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