Grain Crops

the most important group of cultivated plants, yielding grain—man’s basic food product, the raw material for many industries, and feed for farm animals. Grain crops are subdivided into cereals and legumes. Most cereals, including wheat, rye, rice, oats, barley, corn, sorghum, millet, green bristlegrass, foxtail millet, barnyard millet, and pearl millet belong to the botanical family Gramineae; buckwheat is a member of the family Polygonaceae, and mealy amaranth is of the family Amaranthaceae. The grain of cereals contains a great deal of carbohydrate (60–80 percent of the dry weight) and protein (7–20 percent of the dry weight), as well as enzymes, B-complex vitamins (B₁, B₂, and B₆), PP, and provitamin A, all of which accounts for the high nutritive value of cereals to men and animals.

Cereals are raised on all the continents of the earth. The northern and southern boundaries of their natural habitat coincides with the boundaries of agriculture. The most common cereals are wheat, rice (especially in Asia), corn (the largest area sown is in North America), rye (primarily in Europe), oats (in North America and Europe), barley (in Europe, Asia, and North America), millet, and sorghum (in Asia and Africa). The other crops are less common: green bristlegrass and barnyard millet in China, African millet and teff in Ethiopia, pearl millet in India, and mealy amaranth in Peru. In 1970 the total area in the world planted to cereals was 694 million hectares (ha), including 209.8 million ha to wheat, 134.6 million ha to rice, and over 107.3 million ha to corn; the world gross grain harvest was 1,196 million tons. The yield of cereal crops varies greatly. For example, the rice yield in India is 17–20 centners per ha, in Japan it is over 50 centners per ha, and in Spain it is 58–62 centners per ha; the wheat yield in India is 11–12 centners per ha, in the German Democratic Republic 35–37 centners per ha, and in the United States 20–21 centners per ha. In the USSR in 1971, 110.8 million ha were sown to cereals, including 64 million ha to wheat, 9.5 million to rye, 9.6 million to oats, 21.6 million to barley, 0.4 million to rice, 3.3 million to corn, and 2.4 million to millet; the gross cereal harvest was 172.66 million tons and the average yield (in 1970) was 15.6 centners per ha (in Moldavia, 29.3; in Lithuania, 24.5; in the Ukraine, 23.4). Cereals are divided into winter and spring crops, according to the manner in which they develop and the length of their growth and development stage.

Leguminous crops, including peas, kidney beans, soybeans, vetch, lentils, and broad beans also constitute a very widespread group of cultivated plants belonging to the family Leguminosae, subfamily Papilionaceae (lotus). They yield grain that is rich in protein (an average of 20–40 percent of the dry weight; up to 61 percent for lupine). The grain of some leguminous crops contains a great deal of fat, for example, up to 27 percent of the dry weight in soybeans and up to 52 percent in peanuts.