Importance of rice
Agriculture contributed 22% to GDP in 1990. Rice is an important commodity and is subsidized by the government through inputs and price support. As a result, the country attained self-sufficiency in 1984. Indonesia used to import 25% of the rice in the world market in the 1960s and early 1970s, but exported small amounts in the late 1980s. Rice production increased at the rate of 4.6% annually from 1969 to 1988, but this rate has declined recently, and the country has slipped back into import dependence. In 1995 Indonesia imported 3.2 million t of rice to cope with the short-fall in domestic production due to natural disasters.
Rice is the staple food of the people. In rice- growing areas, it is a major source of income for the farmers. With diversification programs, however, other commodities included in the farming systems supplement the income from rice. Rice area increased by 33% between 1969 and 1990. But in Java many ricelands are being converted into nonagricultural use such as housing and industry. There is, however, potential of expansion of rice area in the coastal wetlands in the outer islands.
Rice is grown in a wide range of environments: irrigated lowland, rainfed lowland, tidal swamp, and upland. About 72% of the rice area is irrigated, 7% rainfed lowland, 10% flood-prone, and 11% upland. About 70% of the irrigated rice area can be planted to two crops of rice a year; in the other rice ecosystems, only one rice crop can be grown. Dryland crops, however, usually follow the rice crop in rainfed lowland areas. The average cropping intensity is about 140%. On Java, however, cropping intensity is more than 200%, especially in irrigated and favorable rainfed ecosystems.
Most irrigated lowland rice areas are located in floodplains. However, they can also be found on mountainsides wherever there is water. Rainfed lands are on both floodplains and undulating landscapes. Uplands are mostly on undulating landscape. Most of the flood-prone areas are coastal swamps affected by the rise and fall of tides.
The use of modern rice varieties has increased markedly. Current estimates are that over 85% of riceland is planted to modern varieties. Production of other food crops such as maize, soybean, peanut, and mungbean has been increasing at about the same rate as rice. The area covered by these crops has increased at an even higher rate than rice, averaging about 4.3% annually.
Long-term sustainability is a primary concern, particularly in the uplands. Weather, topography, and poor soils are the chief production constraints.
- Weather. Rainfed lowland, and upland rice ecosystems are most prone to drought stress. However, some irrigated lowlands are also prone to drought, especially in the dry season when irrigation water is in short supply. Others, especially those in low-lying areas, as well as the tidal swamps are subject to flooding.\
- Topography. Erosion is a serious problem in upland rice areas because on steep slopes the fields are neither bunded nor terraced. That is causing serious sedimentation problems in lowland irrigation systems. Alley cropping as well as terracing are being introduced in some areas, but these cultural practices have not as yet been widely adopted by farmers.
- Soils. In irrigated and favorable rainfed lowlands, the relatively heavy application of fertilizers plus the fairly high yields make nutrient imbalance a serious problem. In the upland ecosystem, where soils are more weathered and leached, acidity, Al toxicity, P and other nutrient deficiencies combine to reduce yields. Soil acidity is serious in tidal swamps because of acid sulfate soils. That is accompanied by Fe toxicity, as well as some deficiencies of P and micronutrients.