Rethinking rice

It is now widely accepted that we are running short of fresh water suitable for humans, animals and crops, yet we continue to plant rice and cotton which traditionally have required a lot of water. However, some farmers are now turning to less thirsty methods.

Cotton can be grown either as dryland (reliant on rainfall) or as irrigated cotton (requiring supplemented water supply). Dryland cotton requires full soil moisture profile at the start of the. Season and rainfall during the summer months. However, it also needs vast amounts of fungicides and insecticides.

Rice was domesticated thousands of years ago and since then has become one of the most important crops in the world. This grain is grown all over the world, but primarily in South, Southeast and East Asia. Rice is the second largest cultivated crop worldwide. Ways to cultivate rice without the large amounts of water needed are becoming more prevalent, but there are still downsides to many of these systems.

One system that looks to be promising is the non-flooded mulching cultivation of rice. Much of the time farmers burn the crop residue, releasing air pollution, but using it as straw to mulch can be beneficial to the crops and soil. This technique can increase the organic matter within the uppermost top soil, enriching it over time with carbon and nitrogen as it slowly decomposes.

Not only can it improve soil fertility, but also help prevent erosion. By preventing erosion, mulching can help retain higher levels of water. With this efficient water usage and other benefits of mulching, high yields are obtainable. This method of rice cultivation is an ecological alternative to traditional flooding practices.

Advanced Irrigation Systems

One of the most successful water-saving irrigation systems has used alternating between wetting and drying the fields. In this process, the field is supplied with water, then let completely dry before the next watering. Not only does this cut down on water usage, but it also minimises the methane gas that is produced due to anaerobic decomposition of organic matter in flooded fields.

It also helps support the growth of the rice because it allows for more rigorous root growth and a healthier abundance of aerobic organisms in the soil that help plant growth. One of the most important resources needed for dry rice farming is cultivars of rice that are suited to grow in drier climates.

The dry cultivation of rice involves agricultural practices to utilise and grow living things. This includes the crop being farmed and any animals used in the process. Air and atmosphere, water, and land are all resources affected by this form of cultivation. These resources affected must be conserved in order for these agricultural methods to be sustainable in the long run.

Dry seeded crop requires substantial amount of lower cost but gives higher return. The cost of production in dry seeding is lowered due to saving of labour cost for seedling raising, uprooting and transplanting as well as from lowering the cost for irrigation water. Dry seeding saves about 40% irrigation cost and about 35% labour cost for seedling raising and transplanting.

A number of reports show that dry seeding increases cost for weeding but judicious weed management approach substantially reduces the cost. It is important to note that the reduction of worker is necessary for rice production at the face of recent labour shortage and increased wages. This problem can easily be resolved by switching to dry seeding from the conventional puddled transplanting system especially in the tropical and subtropical regions.

Wheat or many other up-land crops are grown after rice in different areas of Bangladesh. Rice is grown by transplanting on puddled soil while wheat is cultivated after pulverising the soil. Puddling destroys soil structure and adversely affects soil productivity. The deleterious effects of puddling on soil environment are reflected mostly found in the wheat crop.

Anthropogenic activities contribute to global warming by emitting carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Agriculture shares about 60%, 34% and 1% emission of N2O, CH4 and CO2, respectively with major rice based cropping systems.

It has been reported that dry seeding reduces 24-79% CH4 emission compared with puddle transplanted continuous flooded rice production system. Sometimes, dry condition encourages N2O emission but judicious water management in dry seeded system can reduce emission of CH4 and N2O to a greater extent.