Rice: Extraction

From flooded paddy to polished white grain

Most rice grows in flooded paddies across monsoon Asia, with irrigated crops in the US South, California and Egypt and rain-fed upland rice in Africa. Seedlings are transplanted or seeded directly, and the tropics allow two or three crops a year. Harvested paddy is dried, hulled to brown rice and polished to white. Grades are set by the share of broken grains, so 'Thai 5%' means 5% broken. Morgan counted more than eight thousand varieties, from sticky short-grain japonica to fragrant basmati (pdf p. 401). Flooded paddies emit methane, and the crop is thirsty for water.

Almost all rice is grown in Asia on small farms. The main division is water. Irrigated lowland paddies, flooded for most of the season, give the highest and steadiest yields and supply most of the world's rice. Rainfed lowland fields depend on the monsoon and give lower yields, as in north-east Thailand and eastern India. Upland and deepwater rice are small. Planting is shifting from hand transplanting to direct seeding as farm labour gets scarce. After harvest, paddy is milled to white rice or first parboiled, and the milling out-turn decides how much saleable rice each tonne of paddy gives.

Methods compared

How each method works

Fields are levelled, flooded and puddled to seal the soil, then seedlings from a nursery are transplanted by hand or machine. Standing water suppresses weeds. Canal or tubewell irrigation allows two or three crops a year in China, Vietnam, Punjab and Egypt.

High, stable yields; heavy water use (falling water tables in Punjab) and methane emissions.

Bunded fields fill with monsoon rain rather than irrigation. Farmers often grow traditional or fragrant varieties such as Thai Hom Mali. Floods and dry spells can both cut yields.

Low cash cost and premium fragrant grain; weather-exposed and low-yielding.

Seed is drilled into dry or wet soil, skipping the nursery and puddling. It saves labour and water but needs good weed control. It is standard in the US, Australia and much of Brazil, and is being promoted in Punjab and Haryana.

Cuts labour and water use; weeds and uneven stands can lower yields.

Paddy is cleaned, dehusked to brown rice and polished to white. Parboiling soaks and steams paddy before milling, which hardens the grain, cuts breakage and keeps nutrients. Colour sorters grade by broken share. India's FCI pays millers to deliver custom-milled rice at fixed out-turn ratios.

Out-turn and broken share decide profit; bran oil and husk power add value.

Who does it: global

Who does it: India

India is the largest grower (26.6% of world paddy in 2024, FAOSTAT) and the largest exporter (33.6% of 2024 export value; 22.0 Mt in 2025/26, USDA). It curbed exports from September 2022 to October 2024, which lifted Thai 5% prices to $660/t in January 2024 (World Bank).