Sunn hemp (Crotalaria juncea) is an annual legume originating from India that has been cultivated as a fiber crop, green manure, forage, and cover crop. It fixes 50-60 kg of nitrogen per hectare, improves soil fertility, suppresses weeds and some plant-parasitic nematodes. Sunn hemp grows well in tropical and subtropical regions with temperatures between 15-27°C, and yields 18-27 tons per hectare of green biomass when grown for fiber or 5-19 tons per hectare of forage. It can be established through broadcasting or row sowing of seeds and is harvested for fiber around 60-90 days after sowing.

1. Sunn Hemp
HIMALAYAN COLLEGE PUHANA ROORKEE
B.SC AGRICULTURE 3RD SEM SEC-A
SUB- FIELD CROP-KHARIF
SUBMITTED BY:- TABISH ANWAR

2. Content
 Classification & Description
 Origin & History
 Climatic requirements
 Soil requirements
 Establishment
 Yield
 Rotations
 Harvest
 Environmental empact
 Usess

3. Classification & Description
Botanical name:- Crotaleria juncea
Kingdom:- Plantae
Famuly:- Fabaceae
Tribe:- Crotalerieae
Genus:- Crotaleria
Species:- C. juncea
Common names:- Sunn hemp, sunnhemp, Indian hemp,
Benares hemp, Madras hemp, sunn, sunn crotalaria
[English]; chanvre indien, chanvre du Bengale, cascavelle,
crotalaire effilée, crotalaire jonciforme, sonnette, grand
sonnette, tcha tcha, grand tcha tcha [French]; sanhanf
[German]; cânhamo-da-Índia crotalária [Portuguese];
cáñamo san [Spanish]; sunnhampa [Swedish]
 Annual, c. 100–1000 cm tall.
 Many ascending branches, pubescent.
 Leaf simple, c. 2.5v10.5 cm long, c. 6–20 mm broad,
linear or oblong, obtuse or subacute, apiculate,
pubescent on both sides, hairs appressed, silky.
 Petiole c. 1.2–2.5 mm long; stipules almost absent.
 Inflorescence an erect terminal and lateral raceme, up
to 30 cm long, 12–20-flowered. Pedicel c. 3–7 mm
long. Bract minute; bracteoles 2, below the calyx.
Calyx c. 1.8–2.0 cm long, pubescent, teeth linear-
lanceolate. Corolla bright yellow. Vexillum ovate-
oblong, slightly exserted.
 Fruit c. 2.5–3.2 cm long, sessile, pubescent, 10–15-
seeded. Fl.Per. May–September.

4. Origin & History
Crotalaria juncea originated from India and has been cultivated there since the earlier
times of agriculture. It was first reported in Sanskrit literature in 400 BCE. Sunn
hemp is now widely cultivated in many tropical and subtropical areas in the world,
such as India, Bangladesh, Brazil, and even in cold temperate steppes

5. Climatic requirements
Its main area of cultivation in India, sunn hemp is found from 17°N to 30°N and grows
at altitudes between sea level and 1500 m, where average annual temperature
ranges between 15-27.5°C. In Brazil, it grows from the Amazon belt to 22.5°S where
the average annual temperature range is 18-27°C. Elsewhere, it is cultivated in areas
where average annual temperatures are as low as 8.4°C, providing there is a frost-
free growing period of 2-3 months. Sunn hemp can withstand light frost (not less than
-2°C) without injury, but growth and N fixation are reduced. Sunn hemp is a drought-
resistant species and it can grow where average annual rainfall is as low as 200 mm.
Irrigation is necessary for maximum growth and nitrogen fixation (minimum of 25 mm
of water/week). It is more productive with relatively high humidity.

6. Soil requirements
Crotalaria juncea does well on a wide range of soils provided they are well-drained. It
does not withstand waterlogging. When it is grown for fibre, sunn hemp does better
on fairly light textured soil (sandy loam or loam) of moderate or good fertility. For
other purposes, it is possible to grow it on clayey soils of low fertility, provided they
are well-drained. A neutral range of pH is preferred but sunn hemp can grow on soils
with pH ranging from 5 to 8.4 where phosphorus is available. Sunn hemp tolerance of
salinity is generally low but there have been reports of moderate tolerance.

7. Establishment
Crotalaria juncea is propagated by seeds under moist and frost-free conditions, sowing
periods varying upon location and final use of sunn hemp. As a green manure, sunn hemp
is mainly grown during the rainy season. Sunn hemp should be preferably sown in a well-
prepared, fertilized, weeded, seedbed to a depth of 2-3 cm. Seeds can be broadcast or
sown in rows. They germinate within 3 days under favourable conditions. Sunn hemp is a
fast growing species that suppresses weeds by shading them out once sufficient height is
reached . Density of sowing depends on which use sunn hemp is intended for, and on the
place where it is grown. When grown for fibre, sunn hemp should be sown at higher seed
rate in order to promote erect growth, stem elongation and high quality fibre. Under
rainfed conditions, seed rates ranging from 100 to 240 kg/ha were recommended for
broadcasting while only 66 kg were enough for plantation in rows, and resulted in higher
yields. Where irrigation is possible, sunn hemp is sown in small plots surrounded by
furrows in which water is distributed at intervals of 10-15 days.

8. Yield
In India, green biomass production from Crotalaria juncea sown in the pre-monsoon
period ranged between 22 and 27 t/ha. In Cuba, it was possible to get 3.4 t DM/ha in
2 cuts. Worldwide, green matter yield averages 18-27 t/ha and forage yield is about
5-19 t/ha. In Thailand, when cultivated as a green manure after rice, sunn hemp
yielded 2 t/ha of high quality DM in 6-8 weeks.

9. Rotations
Sunn hemp can be used for rotation with many cash crops. In India, recommended
crop successions are sunn hemp-wheat, sunn hemp-potato, sunn hemp-mustard,
sunn hemp-paddy-wheat, sunn hemp-mustard-wheat. The highest performing
rotation was the sunn hemp-wheat rotation in which the yield of wheat was found to
increase by 10-15% . In Brazil, sunn hemp is intercropped with wheat, sorghum,
sugarcane and beans. It is intercropped with cotton in the USA and with kenaf in
Cuba .

10. Harvest
Harvesting should be done at the
flowering stage (60-90 days after
sowing) since the fibre is thinner at this
stage. Harvesting can be done by hand
or with a mechanical harvester. The top
portion of the plants are chopped off
soon after harvesting for use as cattle
fodder. The main portion of the stem is
left to dry on the ground during 1 to 6
days, depending on places, so that it
shed its leaves and becomes ready for
retting. In some areas, stems are left up
to 15 days on the ground and retting
occurs naturally thanks to morning dew
Green manure
As green manure, sunn hemp should
be ploughed in 2 months after sowing
when the plants begin to flower as it
decomposes more rapidly and it will
have a positive N balance at this
stage. It was recommended that
green manure fallow lasts at least 6
months for a positive effect on soil
characteristics. A fallow of up to 18
months was found beneficial for soil
fertility but could have economic
consequences.
Forage
Sunn hemp intended for forage can be
harvested 4 times, starting 6-8 weeks
after sowing and then every 4 weeks.
Sunn hemp should be cut for hay in the
early flowering stage, 1.5-2.5 months
afterplanting.It
It has been recommended to sun-dry
sunn hemp foliage prior to feeding
animals as they do not eat fresh sunn
hemp. However, Indian farmers have
been reported to feed it green to cattle .
When sunn hemp has been harvested
for fibre, the top portion of the stem is
used for fodder or hay after mixing with
paddy straw .
Fibre

11. Environmental empact
N-fixing legume &
Soil improver
Crotalaria juncea can fix about 50-60
kg N/ha within 60-90 days of
cultivation. It provides 60 kg N/ha to
the soil when it is used as green
manure. Sunn hemp has the potential
to improve soil properties, to build
organic matter and sequester carbon
in the soil. It can be used for soil
reclamation.
Weed & Nematode
Control
Sunn hemp is a non-host or poor host
for many plant-parasitic nematodes
including Meloidogynespp.
and Rotylenchulus reniformis. Sunn
hemp has thus been recommended
for rotation with crops prone to
nematode infection, such as potato,
tobacco, etc. Sunn hemp has
vigorous growth and dense canopy,
two elements that are favourable to
weed control.
Cover crop
Sunn hemp has been used as an
alternative to winter legume cover
crops. It can improve soil properties,
reduce soil erosion, conserve soil
water, and recycle plant nutrients.

12. Uses
Sunn hemp, like hemp (Cannabis sativa), is mainly grown as a fibre crop that was
much used in the traditional manufacture of ropes, strings, twines, floor mat, and
fishing nets. It has regained interest in the late 2000s as its fibre is reported to be
more environmentally friendly than synthetic fibres, and having valuable traits for
paper industries. Sunn hemp foliage can be used as a protein source to supplement
poor quality roughage. Raw seeds are toxic and can not be fed to cattle without prior
boiling. The plant can be ploughed down for green manure in the early flowering
stage. It can be useful as an intercropping species, in cereal fields or for other cash
crops. Sunn hemp can suppress weeds thanks to the shade made by its dense
canopy