Rice production systems
Rice is fundamental for food security with approximately three billion people, about half of the world population, eating rice every day. Many of the poorest and most undernourished in Asia depend on rice as their staple food. Approximately 144 million ha of land is cultivated under rice each year. The waterlogged and warm soils of rice paddies make this production system a large emitter of methane. Rice production is and will be affected by changes in climate. Irregular rainfall, drier spells in the wet season (damaging young plants), drought and floods are all having an effect on yields. This has also caused outbreaks of pests and diseases, with large losses of crops and harvested products.
A number of methods and practices are being adopted to address these challenges. For example, production systems have been adapted by altering cropping patterns, planting dates and farm management techniques. For instance, embankments have been built to protect rice farms from floods and new drought and submergence tolerant varieties of rice are being produced and distributed by government institutions and the private sector. In addition, many farmers are diversifying their production systems, growing other cereals, vegetables and rearing fish and animals (such as pigs and chickens). The residues and waste from each system are being composted and used on the land, thereby reducing the need for external inputs. This diversification has increased incomes, improved nutrition, built resilience to shocks and minimized financial risks. The development of advanced modeling techniques, mapping the effect of climate change on rice-growing regions and providing crop insurance are other examples of managing risks and reducing vulnerability. Research on rice cultivation has identified that emissions mainly occur in the few months of the year when the ground is fully waterlogged. A more integrated approach to rice paddy irrigation and fertilizer application has therefore been found to substantially reduce emissions. The use of ammonium sulphate supplements have also been used to promote soil microbial activity and reduce methanogens. In addition, urea deep placement (UDP) technology has been developed where urea in the form of super granules or small briquettes is placed under the soil near the plant roots and out of the floodwater where it is susceptible to loss. In Bangladesh, this practice has shown 50-60 percent savings in urea use and yield increases of about 1 ton per ha.
