Evaluating water productivity and carbon footprint in groundwater-irrigated wheat crop: Impact of on-farm land and water management practices in semi-arid regions

Achieving environmental sustainability of rapid expansion of water intensive crops in arid and semi-arid regions depends on further improvements in water productivity and reduction in energy requirements and its associated carbon footprint for pumping groundwater for irrigated agriculture. This study evaluated a combination of different irrigation methods (Check basin, border flood and micro sprinkler irrigation) and agricultural practices (zero tillage, conventional tillage, and laser guided land levelling) in terms their potential impacts on crop yields, water productivity, energy consumption and its associated carbon footprint for cultivation of groundwater-irrigated wheat crop in semi-arid region of Sonipat district (Haryana, India). Based on the results of field experiments during the rabi (winter) season of 2017-18 and 2018-19, the use of micro sprinkler irrigation resulted into higher wheat grain yield (45.6 q/ha) and water productivity (1.3 kg/m3) due to less volume of the groundwater pumping required. However, the potential gain in the water productivity, calculated based on the irrigation water applied, may or may not result in 'real water savings' depending on the fate of deep percolation as recharge to groundwater levels. Also, the use of micro sprinkler irrigation did not translate into less energy use and lower carbon footprint due to the additional energy requirements of the head losses in the pressurized irrigation system. The use of micro sprinkler irrigation, on average, resulted in 2.5 and 38% higher energy use for groundwater pumping in comparison with the farmers' practice and the laser land levelled border irrigation field, respectively. Overall, the properly graded and sized laser land levelled border irrigation field performed better in terms of resulting 55% higher water productivity, 26% lower energy used, and 36% lower carbon footprint associated with groundwater pumping for wheat irrigation in comparison with the farmers' current practice in the experimental plots. This highlights potential for improving current surface irrigation systems by proper sizing border strips and laser levelling of irrigation fields, instead of a replacement with pressurized irrigation system, to help improve water productivity and reduce carbon footprint for the groundwater-irrigated wheat crop in the study area and similar conditions.