Rice - cultivation
Wet rice cultivation
|Different systems of growing rice have evolved to suit specific environments.|
With wet-rice cultivation, seeds or seedlings are planted out by hand in rows in slightly drained, or puddled, fields. Throughout growing, water levels in paddy fields are kept to a few centimetres deep to prevent weed growth and ensure there's enough water for the plants to grow. This is done by either flooding during the rainy season, or by planting the rice in naturally swampy areas, or by irrigating using a series of canals or wells. Fields are sometimes temporarily drained for weeding and fertilising.
Deep water riceDeep-water rice is a rare and remarkable system of cultivation practised in Bangladesh where annual flooding deeply inundates the land. The rice is seeded as the water is just beginning to rise and the growth of plants keeps up with the rising water level. Here rice plants bear their grain above the surface of the water, sometimes to depths of 5 m.
HarvestingGrains are harvested before they are fully mature, about 30 days after the rice plants have flowered. The rice plants are cut halfway up the stem and either allowed to dry in the field or bundled for processing. The commonest method is harvesting by hand, which is very labour intensive. A sickle is used. Mechanical harvesters are becoming more popular.
ProcessingHarvested grains are threshed to separate the grain from the stalk and enclosing husk. This is usually done by bashing bundles of rice stems on a stone or other hard platform, or using animals to trample on the stems. Threshing machines are becoming more popular.
Winnowing is usually done by shaking or tossing the rice on a basketwork tray. The grain falls onto the mat and husk, chaff and dust are carried away by the wind. Hand winnowing machines are also available. The grain is then dried in the sun ready for hulling or transport to the mill.
Husked or hulled rice is usually called brown rice. This is then milled to remove the outer layers, which is polished to produce white rice. In India and Bangladesh, parboiling is common. This involves soaking, boiling and drying the rice grains before milling. The nutrient value of the kernels is improved with parboiling.