Rice is the dominant staple crop in much of the world and is critically important for global food security, yet rice cultivation is a profligate user of water and a significant source of Methane CH4, emissions, accounting for 9-11% of Green House Gases (GHG) emissions from agriculture. Furthermore, increases in rice production over the last half-century relied heavily on irrigated rice production, which is increasingly constrained by water scarcity. India’s food security largely depends on irrigated rice which consumes nearly 50- 60% of our finite fresh water resources. Flooded rice requires 900-2250 mm of water (average 1500 mm) depending on the water management, soil and climatic factors. Rice requires about 3000-4000 lts for producing 1 kg of grain . Generally irrigated rice fields are continuously kept flooded for a large part of the cropping cycle to suppress weeds and ensure nutrient availability. However, prolonged flooding leads to oxygen-deficient soil conditions, enabling methanogenic microbes to decompose organic matter and release methane, a greenhouse gas with significantly higher warming potential than carbon dioxide. Alternate Wetting and Drying (AWD) Alternate wetting and drying (AWD) is a water-saving technology that lowland (paddy) rice farmers can apply to reduce their water use in irrigated fields. In AWD, irrigation water is applied to flood the field a certain number of days after the disappearance of ponded water. Hence, the field is alternately flooded and non-flooded. The number of days of non-flooded soil in AWD between irrigations can vary from 1 day to more than 10 days depending on the soil type. How to implement AWD? A practical way to implement AWD safely is by using a ‘field water tube’ (‘pani pipe’) to monitor the water depth on the field . After irrigation, the water depth will gradually decrease. When the water level has dropped to about 15 cm below the surface of the soil, irrigation should be applied to re-flood the field to a depth of about 5 cm. From one week before to a week after flowering, the field should be kept flooded, topping up to a depth of 5 cm as needed. After flowering, during grain filling and ripening, the water level can be allowed to drop again to 15 cm below the soil surface before re-irrigation. AWD can be started a few weeks (1−2 weeks) after transplanting. When many weeds are present, AWD should be postponed for 2−3 weeks to assist suppression of the weeds by the ponded water and improve the efficacy of herbicide. Local fertilizer recommendations as for flooded rice can be used. Apply fertilizer N preferably on the dry soil just before irrigation. The field water tube (Pani pipe) The field water tube can be made of 30 cm long plastic pipe or bamboo, and should have a diameter of 10−15 cm so that the water table is easily visible, and it is easy to remove soil inside. Perforate the tube with many holes on all sides, so that water can flow readily in and out of the tube. Hammer the tube into the soil so that 15 cm protrudes above the soil surface. Take care not to penetrate through the bottom of the plow pan. Remove the soil from inside the tube so that the bottom of the tube is visible. When the field is flooded, check that the water level inside the tube is the same as outside the tube. If it is not the same after a few hours, the holes a probably blocked with compacted soil and the tube needs to be carefully re-installed. The tube should be placed in a readily accessible part of the field close to a bund, so it is easy to monitor the ponded water depth. The location should be representative of the average water depth in the field (i.e. it should not be in a high spot or a low spot). Benefits of AWD method to farmers Saving in 30% of water input Reduced incidence of pests and diseases Increase in productivity Tolerance to lodging - Decreased water use also reduced the occurrence of 'lodging' (when rice plants keel over due to heavy rain) and helps the plant grow better tillers (the 'branches' that eventually carry grain) and stronger roots. The resulting improved field conditions (soil stability) helps reduced harvesting costs, as mechanical harvesting becomes feasible. Economic Incentives and Carbon Market Linkages AWD is assumed to reduce CH4 emissions by an average of 50% compared to continuous Flooding. Beyond environmental benefits, AWD opens new income opportunities for farmers through carbon markets. Methane reductions achieved through AWD can be measured and verified using internationally accepted monitoring and reporting protocols, enabling farmers to earn carbon credits. Data centres, airlines, and other energy and water-intensive industries purchase credits to offset emissions and meet net-zero targets, driving demand for verified agricultural abatement. Farmers Earning Potential: For small farmers, this creates an additional revenue stream without altering cropping patterns or increasing financial risk. With ~2.5 tCO₂emissions/ha reduced per crop, farmers can earn ~$37.5/ha, about ₹3,367 per hectare (₹1,363 per acre) per crop. Related resources GHG Mitigation in Rice AWD in Telangana