CHAPTER IV
THE CULTIVATION OF HEMP
The botanical or scientific name for hemp is _Cannabis Sativa_, order, _Moraceoe_, sub-order, _Cannaboidae_. The plant grows wild in Central Asia, but is cultivated in many tropical and temperate regions of both hemispheres. From a cordage point of view the fibre is, naturally, of most importance, but, incidentally, it might be mentioned that the seed is used as a food for birds, and oil is extracted from it; in addition, in tropical countries, a resinous juice exudes from the stalks, leaves and flowers which is made into a violent intoxicant.
The plants in general attain a height of from 4 to 8 ft. or more, and in exceptional cases, such as under good cultivation in suitable soil, approach 20 ft. in height. The leaves are five to nine lobed with serrate margin. The plants are dioecious and the flowers are yellowish-green, small and inconspicuous; the male flowers are numerous and produced in drooping panicles, each flower of five segments; the female flowers are fewer in number, on spikes, single leaf, single ovary, with greyish-green to brownish-grey seed, and rich in oil. The matured stems are usually hollow, and the bark layer very fibrous throughout the whole length of the stem.
The plant readily adapts itself to great changes of climate, and, as already stated, is found in all climates, from the tropical ones of India and China to the frozen regions of Northern Russia. It is adversely affected, however, in the earlier stages of its growth by frost, and always requires a moderately strong sunny period during its growth. It is cultivated in the temperate climates chiefly for its valuable fibre, but a serviceable fibre may be obtained from the plants which are grown in tropical countries.
The most important fibre-producing areas are Russia, Italy and Austria-Hungary, but it is produced in other countries, notably those mentioned below, as well as in Turkey, China and the Southern and Western areas of the United States of America. The Italian fibre is the best of all for fine work, while the Russian fibre, which has a special affinity for tar, is the most satisfactory for use in the manufacture of heavy cordage for maritime purposes.
The approximate annual production of hemp from fourteen different countries appears below--
Russia 400,000 tons Italy 80,000 „ Hungary 50,000 „ India 36,000 „ Siberia 22,000 „ Austria 18,000 „ France 15,000 „ Japan 8,000 „ Serbia 8,000 „ Caucasus 5,000 „ Poland 4,000 „ Bulgaria 2,000 „ Germany 2,000 „ Roumania 1,500 „
The successful cultivation of hemp requires a rich, deep and well-worked soil with a large amount of humus. Alluvial soils are well adapted for the purpose. The strong loam soils of Italy are typical of the best. In all cases a good supply of moisture is necessary, otherwise the crop would be short and stubby and ill adapted for the production of fibre.
The land should be well prepared by deep ploughing, and followed by rolling and harrowing to produce a level and uniform seed bed. The roots of the plants will penetrate into the subsoil if the land is well ploughed, but waterlogged land is unsuitable. A liberal supply of manure is essential owing to the vigorous growth of the crop, and while farmyard manures are the best, the stalks of a leguminous crop may be ploughed in. Manure from animal slaughter-houses is very suitable, and all refuse from the previous hemp crop should be returned to the land. Since the hemp fibre contains a large amount of lime and phosphates, it may sometimes prove advantageous to use dressings which contain these substances.
The seed should be selected with care, and should be tested for its powers of germination. Stored seeds are liable to heat and lose their vitality, and immature seeds are also unsatisfactory. Indian and Chinese seeds are often mixed with home seed. In temperate climates sowing should take place as early in spring as possible, but after the night frosts have passed. The early spring rain and sun are very beneficial, and the foliage which appears moderately early helps to conserve the moisture in the soil as the heat of the sun gets more intense.
The amount of seed to be sown depends upon the type of fibre desired; thus, one bushel of seed per acre for coarse fibre to three bushels per acre for fine fibre are the approximate quantities, and the seed may be sown broadcast by hand, or by machines into drills about 6 or 7 in. apart. In all cases the seed should be well covered to prevent ravages by birds, hence, it is usual after sowing to harrow and roll the fields again for the above purpose, as well as to prepare a level and uniform bed for the germination of the seeds.
Where the land is cultivated with the production of seed as its main object, the seeds should be sown thinly and wide apart, say, in drills or rows from 6 to 7 ft. apart, so that the plants will branch extensively and thus provide facilities for a profusion of flowers. The male plants are pulled after the bloom is shed, but the female plants are allowed to mature under the best conditions so that a large crop may result. Great care must be taken in harvesting and in storing the seed; provision must be made to prevent the deterioration of seed through a process of heating. The average yield of seed per acre is about thirty bushels, but in exceptional cases as many as sixty bushels may be obtained.
Under satisfactory conditions the young plants should appear in from seven to twelve days, after which it is necessary to thin them out and to remove the weeds. While the plants must be wide enough apart to facilitate good growth, there should not be too much space between them when grown for fibre, or branching out will result. If a field has become troublesome with weeds, no crop will eliminate them as quickly as that of hemp.
If desired both male and female plants may be harvested at the same time, but it is often considered advisable to harvest them separately. It is as well to make most of the mixed crop if the labour is available. The male plants may be cut or pulled when the flowers attain maturity or a little after, and when the leaves are changing colour from green to brown. The female plants being shorter may be allowed to remain for about four weeks when the seeds are beginning to ripen.
The yield of fibre per acre of land cultivated is influenced by several conditions, but on good lands under satisfactory conditions of cultivation, an average of 6 to 7 cwt. may be relied upon, and in many cases this quantity is easily exceeded.
After the plants are harvested, a number of minor operations take place in different districts before the plants are subjected to the important process of “retting” or rotting. These preliminary operations are mostly to reduce the weight of the plants and to discard undesirable matter which happens to be easily detached, as well as to secure uniformity. Thus, the tops and roots may be cut off, and the leaves stripped or beaten off, while after the plants have been dried, they may be arranged according to length and thickness. They are then tied up into bundles of suitable bulk for the operation of retting.