Rice is grown on more than 148 million hectares in a wide range of ecosystems under varying temperatures and water
regimes. About 28% of the world's rice is grown in rainfed lowlands. These areas frequently experience severe water deficit due to uncertain and uneven rainfall distribution patterns, and yields are seriously affected by drought. Another 13% of the rice is grown under upland conditions without any surface water accumulation and is always prone to water stress during a part of the growing season Water is one natural resource which influences all facets of life on earth including humans. Allocation of water to agriculture is facing a losing battle with the industrial, domestic, power and other sectors and it is expected that the share of water allocated to agriculture will reduce by 10 to 15 per cent in the next two decades. With dwindling water resources, there is a greater need for rethinking on alternate crops and newer ways of cultivating existing crops along with tools and techniques that contribute towards better utilization of water.The days of the traditional method of cultivating rice in puddled fields by transplanting two to three seedlings per hill and impounding water through most part of the crop season to control weeds seems to be numbered. Growing rice under conventional irrigation usually takes twice amount of water than other crops like corn, vegetables and other high value crops. It is estimated by scientists that production of just one kilogram of rice consumes 4,000 -5,000 liters of water. An average yield of 5 tonnes of rice per hectare would require 250 million liters of water every season. Aerobic rice is a new concept to decrease water requirements in rice production. It is called so because of the reason that it is grown in soil with air as compared with anaerobic soil where oxygen is absent because of irrigation. About 50% of this is enough for aerobic rice. It is commercially grown in Brazil and is being pioneered by farmers in northern China. In the rice wheat belt of India (Haryana, Punjab and Uttar Pradesh) and now in Karnataka innovative farmers have begun to grow aerobically under furrow irrigation in raised bed systems. A fundamental approach to reduce water inputs in rice is to grow the crop like an irrigated upland crop such as wheat or maize. The concept of having the field flooded or saturated is abandoned altogether. Upland crops are grown in nonpuddled aerobic soil without standing water. Soil need not be flooded or permanently kept in saturated condition. Soil need not be puddled, as there is no need for transplanting. Several researchers and farmers claims that the highest yield of aerobic rice was 4.7-5.3 t ha-1, compared with 8.8 t ha-1 of flooded lowland rice. However, the water productivity (g grains per kg of total water used) of aerobic rice was 64-88% higher than that of flooded lowland riceSome of the practices that are being tried out in different countries include Madagaskar method also called as System of Rice Intensification(SRI), Aerobic paddy {also called semi-irrigated paddy( SIP), alternate wetting and drying paddy (AWD)} etc., The below presents comparison of all cultivation operations.Land preparation for aerobic rice is akin to that for any other arable crop like maize, sorghum or any millet. The land needs to be ploughed to let seed germinate without being smothered by clods or hard pan. The land needs to be level enough to facilitate flood irrigation or trapping rain as it falls on the field. Aerobic rice could be sown either by broadcasting, in lines behind a plough furrow or using a seed drill. Fertilizers can be applied alongside. No having to puddle and level the field saves labor and water considerably.Advantage over wetland/irrigated rice· More profitable to farmers as it saves up to 50% labor requirementBeneficial to the society as it releases 50% fresh water from paddy for other usesBeneficial to the environment as these aerobic rice felds hardly produce any methane(Note: Global Warming Potential of methane is 21 times higher than that of CO2 in the atmosphere. Emission of methane from irrigated rice fields and wetlands is not uncommon). Better utilization of applied fertilizers with limited runoff and leaching lossesPolicy initiativesThe cost of water at the point of utility should be worked out and charged to the farmers. This could be an unthinkable proposition at this time in many countries. Irrigated paddy cultivation may have to be regulated. Aerobic rice is a viable option where the shortage of water does not allow the growing of lowland rice.