Oilseeds: GROUNDNUT

The word Arachis hypogaea (groundnut) has been derived from two Greek words,
Arachis meaning a legume and hypogaea meaning below ground (referring to the formation of
pods in the soil).
Ecological requirements
Groundnut is a tropical crop which requires a long and warm growing season while
high rainfall, drought and cold weathers are extremely detrimental for better crop growth.
Soil: pH: 5-8.5
Well drained, light coloured, loose, friable, sandy loam, well supplied with calcium and
moderate amount of organic matter. Soils with poor drainage, high acidity or alkalinity must
be avoided for groundnut cultivation. In U.P. it is grown in alluvial sandy to loam soil while in
M.P., Maharashtra, Gujarat, Andhra Pradesh and Karnataka the crop is taken in black cotton
and red soils. Heavy clay is not fit for groundnut production because soil becomes very hard
during drought which restricts pod formation and development. Even peg penetration becomes
difficult.
Land preparation
For good germination and higher pod yields it is essential to get a weed free well
pulverized, open and aerated seed-bed for sowing the crop. The field must be thoroughly
leveled to avoid water logging in any part of the field. A required tilth may be obtained by
ploughing twice with mould board plough followed by two harrowing and planking. If the
field is infested with white grubs, chemicals like Heptachlor or Chlordane should be drilled at
the rate of 25 Kg/ha before the final harrowing. Organic manures, if to be applied, should be
spread and mixed well in the soil at least 15-20 days before sowing.
Application of manures and fertilizers
Groundnut, being a leguminous crop, does not require very high doses of nutrients. In
general, it needs about 10-20 Kg N, 40 Kg P2O5 and 60 K2O/ha under rainfed conditions while
under irrigated conditions an application of about 20-40 Kg N, 40-90 Kg P2O5 and 20-40
K2O/ha is sufficient. It is observed that Andhra Pradesh soils are deficient in B and
molybdenum whereas North Indian soils are deficient in sulphur, zinc and calcium. These
deficiencies may be corrected by application of 5 Kg borax, 1 Kg ammonium molybdate, 15-
20 Kg of zinc sulphate and 200-500 Kg of gypsum at per hectare rate. Of these, borax and
ammonium molybdate should be applied as basal while gypsum should be band placed near
roots 30 days after sowing. These nutrients should be applied in the zone of pod development
as they are directly absorbed by the developing pods.
The crop responds well to application of FYM or compost at the rate of 6.25t under
rainfed and 12.5 t/ha under irrigated conditions. But under unavailability of organic manures
the above mentioned NPK may be met with inorganic fertilizers. So far as sources are
concerned it is always better to apply ammonium sulphate/calcium ammonium nitrate, single
super phosphate and muriate of potash. In case of very light soils the nitrogen should be applied
in two split doses i.e., half at sowing and half (top dressing as band placed) 30DAS or at the
time of last intercultivation.
Seed selection and seed treatment
To ensure the freedom of seed from seed borne diseases the kernels must be treated
with captan 75 % or Thiram 75 % W.D. P. (Slurry made by mixing 125 g Thiram / 100 Kg
kernel in 500 ml of water)
It is observed that some of spreading varieties have a dormancy of 60-75 days before
they germinate. Therefore, in case of the freshly harvested kernels are to be used for sowing
within the dormancy period, the kernels should be treated with some germination promoting
hormones like G.A. It is advised that, when groundnut is to be introduced in some new areas
where it was never grown the kernels should be treated with Rhizobium culture for better
nodulation, growth and development of the crop. The Rhizobium culture treatment may be done
as under:
Sowing
Time of sowing. In north India groundnut is grown as a kharif season crop where sowing is
done between April-July under irrigated conditions and between June-July under rainfed
conditions.
Seed rate. The seed rate depends upon boldness, spacing and germination percentage of seeds.
Spreading type 60-70 Kg/ha
Bunch type 85-90 Kg/ha
Very bold seeded variety like T-64: 200 Kg/ha
Method of sowing. Groundnut is sown either by dibbling the seeds behind the plough or by
using a seed drill. In case of irrigated crop, it is better to prepare ridges and furrows with a
country plough and dibble the seeds on ridges as this helps in inter cultivation and in better pod
setting of groundnuts. In case of rainfed light soils the crop is sown of flat beds. Usually,
groundnut seeds should be sown at a depth of 5-8 cm in light soils and 4-6 cm in case of
moderate to heavy soil types. To ensure a good and proper germination a light covering with
soil is required over the seed.
Spacing. This varies according to irrigation facilities and type of the seed.
Bunch type and rainfed crop: 20-30 cm X 8-10 cm
Semi-spreading: 30-40 cm x 10-15 cm
Spreading types: 50 cm x 15-20 cm
Irrigation
Generally, groundnut is grown as a rainfed crop during kharif season though its water
requirement varies from 500-700 mm but if crop is caught in a long spell of drought, especially
at the pod formation stage, supplemental irrigation is given. In case of irrigated crop, the
frequency of irrigation depends upon soil texture and the interval between the irrigations ranges
between 8-12 days. The critical stage for irrigation is branching, flowering and pod
formation. There should be sufficient moisture at the sowing time in the field, thus if the crop
is to be sown before onset of monsoon the field should be given one light pre-sowing irrigation
for better germination of the seeds. The winter and summer crops are always grown under
assured irrigation. The irrigation must be stopped about 20-25 days prior to maturity.
Weed Management
Weeds result in a severe competition with the crop and cause a considerable reduction
in the yield to the extent of 20-40% based on nature of weed infestation in the field. To kept
the soil loose and friable and the field free from weeds the crop should be given a hand weeding
20-25 DAS and one or two hoeings, the first at the time of weeding and second about a fortnight
later. The intercultural operations should be stopped after the pegs have started going into the
soil. The bunch and semi spreading types should be given a light earthing to facilitate the
maximum penetration of the pegs into the soil.
Mixed Cropping
The groundnut crop may successfully be growing mixed with several erect growing
crops like bajra, castor, sesamum, cotton, maize, sunflower etc. The number of groundnut rows
between two rows of any of the said crops depends upon their inter-row spacing and type
groundnut, i.e. bunch, semi-spreading or spreading to be grown.
Harvesting and after use
Yellowing of leaves is the prominent symptom of maturity. The leaf yellowing is
associated with leaf shedding (particularly, the older ones), development of proper colour of
shell and a dark tint on the inner side of the shells. Usually, the crop takes about 120-140 days
to mature depending upon the variety and the harvesting is done in the month of October-
November accordingly. At maturity the crop is badly damaged by crows, jackals, etc. which
need vigilance. After maturity the bunch and semi-spreading types are generally harvested by
hand pulling at an appropriate soil moisture, while the spreading types are harvested by digging
out the plants with the help of khurpi, spade or by ploughing the field. The left-out pods in the
soil are collected by hand, later. The pulled-out plants are stacked in a safe place for a few
days to dry and are stripped afterwards. The pods are cleaned and dried to a safe moisture
content not more than 5% before they are stored because dampness will cause fermentation of
pods and allow to develop the poisonous molds like Aspergillus flavus in the kernel. These
molds lead to contamination with aflatoxin which create a health hazard to both human and
cattle.
Drying
Generally, moisture % in pods are found to be around or excess of 40% (on wet basis)
depending upon stage of maturity at harvest. The pods must be dried to 5-10 % moisture for
safe storage. Drying rapidly prevents molding and other forms of deterioration. Perfect drying
helps in maintenance of the desirable flavour, texture, germination and viability of kernels etc.
Yield
The pod yield is controlled by several factors like climate, soil and varietal potentiality.
In general, the irrigated groundnut crop produces about 30-35 quintal pods/ha and rainfed about
15-20 quintal pods/ha. The yield of haulms is usually two to two and half times of pods' yield.
The shelling percentage ranges between 70-75% and the kernels have on an average 45% oil
and 20%protein in them.
Storage
All the damaged or injured pods must be sorted out before they are stored. Well cleaned
and dried pods to 5% moisture level should be stored after filling in gunny bags. These gunny
bags are stacked in a store room in tiers comprising not more than ten bags in each tier. The
tiers must be staked on wooden planks in such a way that the air keeps on circulating to avoid
damage from dampness, rate etc. The room should be inspected periodically and proper control
measures of rats and pests should be taken. The store should be fumigated, if needed and made
airtight. The groundnut should be stored in the form of pods rather than kernels but the broken
and damaged pods must be taken out and discarded. Apart from this the undersized /
underdeveloped and unfilled pods (pop-pods) should also be discarded because their presence
reduces the market price.