OIL-PRODUCING SEEDS: HEMP

Pubdate: 1896 Source: 1895 Yearbook of the United States Department of Agriculture (pgs 198-199) Author: Gilbert H. Hicks; Assistant, Division of Botany, U.S. Department of Agriculture.

Hempseed oil comes from an annual plant of the nettle family (Cannabis sativa), which is indigenous in central Asia and the East Indies. It is cultivated in India, Persia, China, North America, Germany, and, more than anywhere else, in Russia. It grows from 4 to 8 feet high in waste and cultivated ground. The odor of the fresh leaves sometimes produces headaches, while the celebrated narcotic, hashish, is prepared from a gelatinous resin contained in the leaves and stems. The latter also furnish the well-known fiber used for cloth and cordage.

The male and female flowers are borne on different plants. The nut-like fruits, commonly called seeds, are used in great quantities in bird food. They are nearly egg-shaped in outline, flattened at the margins. Color, dark gray, with fine, net-like, whitish markings on the smooth and shiny surface. Each fruit is completely filled with the seed proper, which is of the same shape and about 4mm. long by 3 mm. wide and 2 to 3 mm. thick. The seeds contain no endosperm, but are filled with a whitish embryo which yields 30 to 35 per cent of a peculiar-smelling, mild-tasting oil, greenish yellow when freshly pressed, becoming brownish yellow with age. Hempseed oil is used to a considerable extent in the preparation of paints and varnishes, although it does not dry as readily as linseed oil. In Europe it enters largely into the composition of soft soaps. Sometimes it is used in the Old World as an illuminant and, rarely, for food.

Hemp will thrive in most parts of the United States, and is said to produce from 20 to 40 bushels of seed to the acre, worth about $2.50 per 100 pounds. With extra good care and soil the yield may reach 50 to 60 bushels. The seed should be planted in drills, early in April in the South, two weeks later in the North. The young plants are thinned out when a foot high, and must be kept free from weeds. The male plants should be pulled as soon as they have shed their pollen, so as to allow the seed-producing plants plenty of room and all of the available soil food.

Hemp should be harvested promptly as soon as the seed begins to drop, which always takes place after a sharp frost, if not before. The seeds scatter easily; hence hemp should be cut early in the morning when the dew is on, and great care exercised to prevent waste. When cut, hemp should be set up in loose shocks to dry, a sheet being placed under each one, and some protection afforded from birds, as they are fonder of this seed than almost any other. Drying is completed by spreading the plants out on a tight barn floor, where they are thrashed by hand.

Hempseed, notwithstanding its oily content, loses its germinative power quickly, usually by the end of one year; hence only fresh seed should be sown. Neither cracked nor dull-looking seed will germinate well. Hemp culture in America is mostly confined to Kentucky and Missouri, principally the former State. The value of hemp for fiber, birdseed, and oil would seem to make its cultivation a very profitable one.