Each year, hundreds of millions of tons of rice straw and husks are produced. These rice residues generally have little or no commercial value. Burning of rice residues causes severe air pollution in some regions, but incorporation into the soil is a major source of methane emissions from rice fields. Innovative uses of rice straw and husks may generate new income opportunities for the rice-farming sector and help to mitigate the effects of climate change.
In addition to a range of rice-based food and drink products (for humans), there are also many non-edible rice products. These make use of the non-edible parts of the rice plant or of components of the grain itself:
Rice straw, more or less equivalent in production weight to grain, is used as fuel for cooking, roofing material, livestock feed, fertilizer, and as a medium for growing mushrooms.
The hulls or husks of rice grains, which form about 20% of the grain weight, are used for fuel, bedding, and incubation material, and as a seedbed medium, as well as being sometimes incorporated in livestock feeds, concrete blocks, tiles, fiberboard, ceramics, cement, filters, charcoal briquettes, and cooking gas production.In addition to its use for edible/food products such as flour and oil, rice bran, which forms 5–8% of the grain weight, is used as livestock feed, a pickling medium, a medium for growing mushrooms, and as a growing medium for some enzymes. Rice bran wax, which is obtained from rice bran oil, is sometimes used instead of carnauba wax in cosmetics, confectionery products, shoe creams, and polishing compounds.
Rice paper may refer to strong, translucent paper, traditionally made mainly from rice straw (but now commonly made from other materials, such as mulberry or hemp plants) and used for writing and art or as room dividers, especially in China and Japan. However, rice paper can also refer to edible paper made from rice starch used mainly in Chinese and Vietnamese cuisine.
Rice contains many compounds in the grains that promote shiny hair and good skin. Several countries are now making face washes, liquid shower soaps, and hair products from rice, including Japan, Korea, the Philippines, and Thailand.
Certain parts of some rice varieties (mainly brown rice and rice bran oil) are used as medicines or remedies in the traditional treatment of illnesses, especially for skin and gastro-intestinal conditions. This is likely based on the fact that rice bran contains a high proportion of fiber (known to assist in the absorption of fats in the gut, to decrease the levels of cholesterol in the blood, and to aid digestion with mild laxative properties) and contains vitamin E (known to have antioxidant properties). Scientific studies have shown that rice products may have anti-cancer properties and the potential to treat diseases such as diabetes, kidney stones and heart disease.
Parts of the rice plant are also used in some cultures to make decorative or ritual objects.