There are many varieties of the hemp plant, four or five having been grown in the United States, though it is said that the bulk of the seed at present sown is the China hemp and a Japanese variety. In California, Japan hemp has yielded 7,000 pounds to the acre at a total cost of $67, and a value of eight cents per pound. Five varieties are cultivated in Europe, a common form reaching a height of five to seven feet; Piedmontese or Bologna, an Italian variety that averages 12 feet in height; China hemp, introduced in 1846; a small hemp found in the valley of the Arno and around Tuscany; and Arabian hemp, cultivated for the resinous principle or drug.
Limestone soils, clayey loams and the al luvial soils of the river bottoms are best adapted to hemp culture, and the seed bed should be almost as carefully prepared as for flax. Generous fertilizing both with stable ma nure and chemical fertilizers is well repaid in quality as well as quantity of crop. One to three bushels of seed are sown per acre broad cast and highly covered. The planting,. in K.en tucky, usually begins in April, and the crop may be harvested in 100 days. The most ap proved practice is to allow the hemp to lie on the ground, turning it over at intervals, till the leaves drop from the stalks. It is then gath ered into stacks and water-retted during the following winter. Upwards of 300 machines for breaking hemp have been patented, but the Shely Hemp Gin seems to be the only one which has met with popular favor. It requires a crew of 15 men and turns out 1,000 of clean, straight fibre per working hour. For further particulars regarding the culture and preparation of this fibre, see Special Reports Nos. 1, 8 and 11, office of Fibre Investigations
of the Department of Agriculture, and Hemp Culture in the United States, Year-books of Agriculture for 1911 and 1913. See also the of the Economic Products of In dia.' While some 300 patents have been issued in this country for hemp machines, the bulk of the fibre is extracted by means of the old fashioned, clumsy wooden that has been employed from time immemorial and without improvement or change. With one of these breaks a Kentucky negro can extract perhaps 150 pounds of fibre in a day. The breaks used in European hemp countries are little better, though they are smaller and less clumsy. The best foreign hemps are water retted, the stalks dried with great care, often in kilns, and therefore are more evenly pre pared and the fibre soft, strong and light in color—almost white as in the Italian and French hemp. On the contrary most of the American hemps are dew-retted, and are ex posed to alternate freezing and thawing, as the stalks lie on the ground, giving an inferior product, uneven and very dark in color, often a slate gray. Those water-retted bring double the price of the dew-retted. See CORDAGE; CORDAGE INDUSTRIES ; FIBRE; FLAX ; MANILA HEMP; RAMIE; SISAL.
Consult United States Plant Industry Bureau Bulletins 46 and 221; and Moore, B., Study of the Past, the Present and the Possibilities of the Hemp Industry in Ken tucky' (Lexington, Ky., 1905) ; United States Foreign and Domestic Commerce Bureau's Special Agents' Series No. 74, Jute and Hemp Industries.'