Ikisan -Importance of soil condition and nutrient availibility in groundnut cultivation
Soil Conditions And Nutrient Availability
To obtain maximum pod yield, adequate
supply of every essential nutrient as per plant requirement at different
growth stages has to be ensured.
Soil is the main source of nutrients
to the plant.
But the nutrients are rarely available
in adequate quantities in the soil to fulfil the nutritional needs of
the groundnut crop, especially when the high - yielding varieties are
The nutrients in the soil may be present
in insufficient quantities or in complex form which hinder their availability
to the plant.
deficiency is therefore mainly due to soil conditions.
soils for groundnut cultivation are red sandy soils, sandy loam, alluvial,
coastal alluvial, mixed red, black and medium black soils.
of the nutrients depends on factors such as pH of the soil, moisture
content, cropping pattern, rate of release of micronutrients from the
soil mineral, and the presence of other ions in the soil.
pH ranges (alkaline soil pH > 8 and acid soil pH< 6) are not well
suited to groundnut.
well known that soils pH influences the availability of the nutrients.
acidic and alkaline soil pHs the availability of most of the nutrients
Plant-nutrient deficiency at different levels of soil pH
Range of soil pH
The soil pH of 6-7.5. seems to be ideal
for the availability of nutrients. Alkaline and acid soils are more
prone to nutrient deficiency in the plant.
The presence of other ions in excess
also influences the availability of nutrients to the plant, e.g on calcareous
soils iron deficiency is due not to a lack of iron but to its being
immobilized or inactivated by carbonates or bicarbonates.
In coastal soils affected by salinity,
the uptake of nutrients may be reduced. These soils may be deficient
in zinc also.
Ikisan - Importance of Sulphur and Calcium In Groundnut
Sulphur and Calcium Importance In Groundnut
Sulphur plays an important role in the metabolism of groundnut
plant. It is important for the synthesis of proteins.
It helps in biological oxidation-reduction
It plays an important role in chlorophyll
Soils supporting groundnut are generally
poor in sulphur.
Acid soils are deficient in sulphur.
The uptake of sulphur from the soil is
generally in the form of sulphate.
The availability of Suphur to plants
depends on the ability of the soil to supply sufficient soluble sulphate.
Wide occurrence of Sulphur deficiency
in the country's soils has been reported.
Soils with less than 10 ppm available
sulphur are deficient for groundnut.
The leaves turn pale. young as well as
middle leaves show chlorosis.
under severe conditions the leaves
become papery .
The deficiency symptoms of iron and sulfur
appear together in groundnut.
S-deficient plants have low chlorophyll
soil application of 250kg /Ha gypsum is
able to improve the deficiency and increase the pod yield.
Gypsum should be used when P is not deficient
and superphosphate when P is also deficient.
The reports available indicate that S
increases the protein and oil content in groundnut.
take part in the various metabolic processes of the plant.
of the nutrients in the plant will bring about derangement in the metabolism,
which in turn manifests in the development of visible deficiency symptoms
such as yellowing of the leaves, interveinal chlorosis, purpling of
the leaves and stems, stunted plant growth and other abnormalities.
deficiency symptoms are characteristic of a given element.
case of deficiency of more than one element, or severity of deficiency,
the identification of the symptoms for a given nutrient would be difficult
and requires experience.
Calcium (Ca) requirement of groundnut
plant is quite high and it is more during the pod-filling stage.
Acid soils are deficient in calcium.
Serious Calcium deficiency may occur
in neutral and alkaline soils of sandy texture.
Calcium is needed for good plant growth
and pod yield.
If Calcium is deficient in the fruiting
zone, aborted and shrivelled pods (pops) are obtained.
The kernels have dark plumule.
The germination and seedling survival
Distinguishing foliar deficiency symptoms
of calcium in groundnut are not known.
Symptoms like pitted areas on lower surface
of older leaves are found.
Later on large necrotic spots are found
on both the surfaces, which give leaves a bronze colour.
Youngest foliage appears distorted.
To get good yields, the availability of
Calcium in the fruiting zone must exceed a defined critical level during
the time of pod development.
The requirements of calcium for groundnut
are 1 meq/100 g soil in the root zone and 3 meq/100 g soil in the pod
Depending on soil test, 250-500 kg/ha
gypsum may be applied in the fruiting zone at 0-5 cm depth.
Being a leguminous plant, groundnut may
not respond to large application of nitrogen.
It is, however, a major limiting factor
in the proper growth of groundnut plant.
In early stages of plant growth, nitrogen
is very much in demand.
Nitrogen is recommended in two equal split
doses, i.e. half of the nitrogen at the time of sowing and the remaining
half after 35-40 days of sowing preferably after weeding.
For obtaining higher fertilizer efficiency,
it should be top-dressed at proper moisture level in soil followed by
Nitrogen may be supplied preferably in
the form of ammonium sulphate because it also contains sulphur, a nutrient
also required by groundnut for synthesis of oil besides nitrogen.
The following nitrogenous fertilizers
are commonly used in groundnut crop.
Ammonium Sulphate [(NH4)2 SO4—20%
It is oldest N-synthetic fertilizer.
It contains about 20% N in ammonium form
and is a white crystalline salt.
It is readily soluble in water but only
It has a strong acidifying action on the
Among the available nitrogenous fertilizers,
ammonium sulphate is preferred for groundnut crop because of its sulphur
It can be used in both rainfed and irrigated
In top-dressing also, it can be used before
irrigation or after irrigation at the time of proper soil condition.
The ammonium ion (NH4+)
is absorbed by negatively charged colloids in the soil and its mobility
through leaching is hence reduced.
It can be absorbed directly by plant roots.
Urea [CO(NH2)2-46% N)
It is a white granulated organic compound
and contains 46% N
Urea is easily soluble in water (1.0 kg/litre
at 200C) having low specific weight (bulk density, 0.7 kg/litre).
Urea is very popular and commonly used
It can be used as basal-dressing in rainfed
as well as irrigated conditions, for while top-dressing in rainfed,
as well as irrigated conditions, but while top-dressing it should be
applied at optimum soil moisture followed by harrowing.
Decomposition of urea in the soil is effected
by microbial enzymes (urease) and is temperature dependent.
It is converted to ammonium carbonate
and then to ammonium which usually immediately further gets converted
Loss of gaseous ammonia may occur under
certain conditions (high soil reaction and temperature) after applying
the fertilizer on the soil surface.
It can also be used as foliar nutrient
but proper care should be taken about its concentration since higher
concentration may burn the foliage of groundnut.
Calcium ammonium nitrate (NH4NO3
+ CaCo3-26% N)
It is granulated white (sometimes green
or brown) water-soluble inorganic compound and contains 26% N.
Due to Ca content it is an important fertilizer
for groundnut crop.
As it contains both the forms of annomical
and nitrate nitrogen, it is easily available to the plant root.
It can be used in basal application as
well as in top-dressing.
Top-dressing should be done after irrigation
at proper soil moisture and should be followed by harrowing.
Large amount of potassium is required
by the groundnut crop but as the Indian soils are generally rich
in potassium, unless the soil has less than 150 kg available K2O/ha,
there is no need to apply potassium.
Normally, about 50 kg
K2O/ha will be adequate for the soil deficient in potassium.
Potassium may be supplied regularly in
the form of potassium sulphate.
All K2O should be applied at
the time of sowing as a basal-dressing by adopting furrow placement
Potassium chloride-muriate of potash (KC1-60% K2O)
It is a white or slightly coloured, granulated,
water-soluble fertilizer having 60% K2O.
When applied to the soil it is readily
available to the plant root. Entire quantity of fertilizer may be applied
to the soil prior to or at planting time.
However, recent studies have indicated
that application in two splits is superior than single application,
depending upon the texture of the soil.
Potassium sulfate (K2SO4-50% K2O)
It is a common fertilizer for groundnut
which contains sulphur besides 50% K2O.
Due to its sulphur content, potassium
sulphate is a better fertilizer for groundnut than potassium chloride.
The K component is water soluble and,
therefore is readily available to the plant roots.
It can be used either as basal-dressing
The sulphate ions are retained by the
soil more strongly than chloride ions but less strongly than phosphate
The sulphate ions are retained more in
the soil with high content of calcium than in soils with low calcium
Thus application of potassium sulphate,
generally, will be more appropriate in soils which are calcarious in
nature and alkaline in reaction.
Under wet conditions, it is preferable
to apply potassium sulphate than potassium chloride as leaching of potassium
sulphate will be less.
Similarly potassium sulphate will be
more effective on light and medium soils than on heavy soils.