Botanical name : Crotolaria juncea L.
Family : Leguminoceae
Origin : India and Burma

Economic importance
Sannhemp is grown for (1) green manuring (2) fibre (3) fodder and (4) seed purposes.
Sannhemp is one of the importance fibre crops of India. It plays importance role in the National economy both as raw material for industries and also as a foreign exchange earner through export. White fibres are used for manufacture of tissue paper and paper for currency as it contain high percentage of cellulose and low amount of lignin. The farmers themselves make use of the fibre for making ropes. It is used for making cordage of all kinds, twines, nets, mattings etc. It is also usd for making rug, sack etc. It is grown for green manuring which adds about 40-60 kg N ha into the soil. It is also a source of cellulose for rayon and artificial silk. It is also considered as the king of green manuring crops.

Land preparation
One or two deep ploughing with mould board plough and 2 to 3 harrowings followed planking should be carried out.

Seed rate
- For fibre fodder and green manuring purpose – 80 to 100 kg ha.
- For seed purpose – 25 to 40 kg / ha

Sowing time
- June – July

Method of sowing
- Line sowing by seed drill at 3 to 4 cm depth for seed crop.

Spacing - 30 x 7-10 cm for seed crop and broadcasting for green manuring purpose.

Fertilizers - Only 50 kg P2O5 / ha as basal

Interculturing and weeding
The line-sown crop should be intercultured and weeding should be carried out as and when required to keep the crop weed free. Interculturing helps in conservation of soil moisture also.

Harvesting
For fibre crop, the crop is harvested at the pod formation stage for good quality fibres, colour and luster. Too early or too late harvesting spoils the fibre quality. Harvesting of the fibre crop is done by cutting the whole plant close to the ground with the help of sickle. The leafy top portion of the plants may be chopped off and used either as fodder or may be plougher down in to the soil to add organic matter. After shedding of the dried leaves, the plants are tied into bundles of convenient size having 50 to 100 plants in each bundle. Steeping, retting and extracting is followed as per jute crop. For extracting fibres the bundles are tied on drying and submerged in water for 5-6 days for retting and then the fibres are peeled off.

Extraction
Fibre is extracted single plant wise by breaking the lower ends of the plant and then stripping upward from the bottom. After extraction, the peeled fibres should be washed thoroughly in clear water to remove the dirt and other adhering plant materials. After drying the fibres, it is graded and bundled into small “Moras” for marketing.

Yield : 8 to 10 q/ha.

Varieties : K-12, M-19, M-35, S T-35, Nalanda sanni

Steeping and retting
The bundles are brought to the nearest ponds, pools or streams and arranged side by side to form a platform in water for steeping. In some States, bundles are covered with hyacinth, grass etc. and the “Jak “ is weighed down 10-15 centimeters below the surface of water by stone blocks, concrete slabs or seasoned logs, Substances rich in tannin like freshly cut logs or clods should not be used as weighing materials because it will turn the colour of the fibres into dark. Care should also be taken to see that while weighing down the “Jak”, the bundles do not touch the bottom of the retting tank. Retting in slow running water is better than retting in stagnant water. This process is complete when the fibre is loose enough for extraction and is complete separated frm the sticks. This can be determined by examining one or two plants from the bundles after two or three days of retting. The period of retting may very from 3 to 15 days depending upon the temperature of retting water and the month of harvesting. In September, retting takes place generally within three to seven days, while in December, this period may range from 12-15 days. The optimum temperature for retting is 21 to 27o C.

Yield of green material (NPK addition in soil) and fibre
The yield of green material for green manuring crop is about 10 to 15 tons/ha with deposition of 60-70 kg N, 30-35 kg phosphorus and 30-35 kg potash per hectare. Sannhemp contained 2-4 per cent fibre on the basis of the weight of green stem or 8 to 12 percent in terms of dry weight. The yield of fibre from a good crop of sannhemp is about 8-10 quintals of fibres per hectare.