This study was conducted with the objectives to (i) assess the agricultural C emissions in relation to predominant farming systems in Punjab and Ohio, (ii) evaluate C use efficiency of production systems, (iii) compute the sustainability index, and (iv) formulate a set of recommendations to make the agricultural practices in both states more C efficient by increasing the ratio of C output:input. The data on C based input into the soil for predominant crops were collected for Ohio, USA and Punjab, India. Data collected included the amounts of fertilizers (N, P, K), herbicides and pesticides used for each crop annually, tillage methods, cropland area, total production of each crop, and the area under various farming systems, water management practices, such as tube well irrigation, and total number of livestock. These data were used to calculate C equivalent per hectare of input and output, and sustainability indices which is a measure of C use efficiency. The C sustainability indices were computed to identify sustainable soil and crop management practices. There was a linear relationship observed between C input and C output in Punjab. With an increase of 1 Tg/yr of C input, the corresponding C output increased by ~ 12 Tg/yr (Fig. 3.24), with an output:input ratio of about 12. Likewise, in Ohio a linear relationship was apparent between the C input and net C output in the initial years (from input = 0.1202 - 0.4288 Tg/yr). And after that, the graph almost reached a plateau. The average C sustainability index value for Ohio in the last 15 years is around 35-43, which is almost 2.5 times that of Punjab. Since 1989 there has been a huge shift from conventional tillage to reduce and conservation tillage in Ohio. During the same time, the fertilizer consumption of Ohio decreased significantly. Fertilizer use in Ohio is based on the soil test and crop requirement. The use of scientific methods causes reduction in fertilizer use. Judicious use of fertilizers is a more C efficient practice. No till is being practiced on more than 35% of the cultivated area presently. Conservation till practices are more C efficient than conventional tillage practices. More than 30% of crop residues are retained during conservation tillage, and approximately 15-30% during reduce tillage practices. In Punjab, crop residues are removed resulting in loss of C from SOC pool. Hence C efficient systems, such as those used in Ohio are more sustainable than inefficient farming systems such as Punjab. Policy issues are identified with regards to the management of crop residues to increase the SOC pool, control erosion and improve soil quality. These technologies include no-till farming, drip irrigation, cover cropping with residue mulch, precision agriculture, judicious use of chemical fertilizers, use of nano technology based applications for soil such as zeolites, use of high analysis fertilizers, contour farming, integrated nutrient management practices and cost effective utilization of organic waste. Imposing taxes on fertilizer use, trading C credits from agriculture, deciding the appropriate subsidies, maintaining the desired fertilizer and food price ratio, restricting burning of straw in open fields are some of the policy recommendations which would help in maximizing the C-use efficiency and in decreasing the C footprints of agriculture in Ohio, USA and Punjab, India.