Paddy is rice without being separated from its shell. Paddy is the seed of the grass species Oryza sativa. As a cereal grain, it is the most widely consumed staple food for a large part of the world's human population. Since sizable portions of sugarcane and maize crops are used for purposes other than human consumption, rice is the most important grain with regard to human nutrition and caloric intake, providing more than one-fifth of the calories consumed worldwide by humans. There are many varieties of rice and culinary preferences tend to vary regionally. The annual production of paddy is about 1 million tons which is grown in Marmara and Black Sea regions of Turkey. Rice hulls (or rice husks) are the hard coverings of grains of rice. In addition to protecting rice during the growing season, rice hulls can be put to use as building material, fertilizer, insulation material, or fuel.