Of the several inputs essential for crop production, fertilizer/nutrient
management is of paramount importance.
Widespread deficiency of N.P.K. and micro-nutrients like zinc show
the need to apply for getting optimum yield of maize.
The maize plant is a heavy feeder, requiring an intelligent fertilizer
programme. It requires a lot of nitrogen, phosphorus, potassium and zinc.
It responds very well to heavy nitrogen fertilisation, at a concentration
that would normally cause lodging of other cereal crops.
The nutrients are to be replenished through balanced fertilizer application
and integrated use of nutrients. These principles are not new to crop
production but assumes significant importance in view of steep hike
in fertilizer prices and abolition of subsidies.
Hence there is need to get acquainted with N.P.K. and Zn nutrition
and their management as they are not replenished in sufficient quantities
to produce optimum corn yields.
A Judicious application of organic manure such as well rotten compost
or FYM at the rate of 10-12 t/ha about 25 days before sowing the crop
has been found to be most ideal for an increased crop yields.
Maize plants throughout the cropping season take up nitrogen.
There is gradual increase in the requirement of nitrogen by the growing
maize crop, the highest nitrogen requirement being exhibited at the
flowering stage. Subsequently, the demand for nitrogen starts declining.
Therefore, it is utmost important that adequate nitrogen supply should
be ensured from germination to the flowering stage.
In young plants, N deficiency causes the whole plant to be pale,
yellowish green and have spindly stalks.
Yellowing on the tips of the leaves appear later. Yellowing
begins on the older lower leaves and progress up the plant.
The N recommendation for major maize growing areas of Karnataka are
Kharif Maize : Irrigated – 150 Kg ha-1
Rainfed – 90 to 100 Kg ha-1
Rabi Maize : Irrigated – 150 Kg ha-1
Time of Application
To achieve adequate nitrogen supply, nitrogen is usually applied in
three equal splits at sowing, knee high stage and tasseling stages.
In non-sandy soils, uniform supply of nitrogen can also be accomplished
by two equal application – 50% at sowing and remaining half at knee
It is the next most important plant nutrient after nitrogen which
is found deficient in most maize growing areas of Karnataka.
It has beneficial effect on root growth and maximum root development
is completed until knee high stage. Thus the nutrient should be applied
initially at the early stages.
Phosphorus deficient plants will be dark green with reddish
purple tips and leaf margins. Plants are smaller, grow slowly,
and remain shorter throughout the growing season.
The P2O5 recommendation for major maize growing
areas of Karnataka are as follows :
Kharif Maize : Irrigated – 75 Kg ha-1
Rainfed – 50 Kg ha-1
Rabi Maize : 50 to 60 kg ha-1
Time of application
Since it plays major role in root development, entire dose of phosphorus
should be applied in the early stages.
Because of its low solubility in water, it should be applied in moist
zone to be transformed quickly for early absorption by plant.
It’s application in single dose as a placement below seed (band placement)
is highly desirable.
;It is essential for vigorous growth of the plant and for so many
other metabolic activities. The young seedling does not need much potassium,
but the rate of uptake jumps upto a peak level during three weeks prior
Shorting of internodes
Shortening of internodes, yellowing of leaves and firing at
the margins of lower leaves.
Deficiency symptoms usually appears during the time, the plant
is one foot tall to the time of tassel emergence.
Potassium is not found deficient in most of the maize growing
soils. However, placement of 30-40 kg ha-1 K2O,
a little away from the seed is generally bound to be quite adequate.
Aa there is negligible amount of leaching and most of uptake is completed
early, entire potassium is to be applied as basal dose along with phosphorus
at the time of sowing.
Higher uptake of other nutrients increases the demand of Zinc. Zinc
deficiency symptoms are described as “White bud” in maize.
Appears rather early and plants become severely stunted owing
to the restricted growth of inter nodes and leaf lamina.
Deficient plants show a broad band of bleached tissues on each
side of the leaf midrib, beginning from the base.
Basal application of Zinc sulphate at 20-25 kg ha-1 after
every three to four maize harvests becomes essential.
At later stages of growth deficiency can be corrected by foliar application
of 5% ZnSO4 dissolved in water with half the quantity of
All the three major nutrients should be applied in proper quantity
& proportion and at a right time and place, also right method of
application should be followed to obtain optimum grain yields of maize.
Maize requires a regulated and assured supply of nutrients particularly
nitrogen throughout its growing period right from seedling stage to
grain filling stage.
The nitrogen utilization pattern is found to be increased from seedling
of knee-height and reaches to the peak at tasseling stage when the plants
remove nearly 4-5 kg N/ha/day.
Plants respond to a dose of 120 to 150 kg N/ha and so is the recommendation
for hybrids and composite varieties, however, in certain cases the economical
yield of maize grains has been obtained even upto the application of
200 kg N per hectare.
The best results from applied nitrogen may be achieved when nitrogen
is applied in three splits viz., 1/3rd at sowing, 1/3rd
at knee-heigh stage (about 35-40 days after sowing) and remaining 1/3rd
at tasseling stage. Amongst the method of fertilization placement below
the seed and side dressing of nitrogen at second and third split applications
gave the best results. The crop needs relatively lesser nitrogen when
grown during winter season, which may be accounted for higher uptake
and lower loss of the nutrient from the field. Similarly,, during spring
season when the crop is taken after potato, peas or gram it needs low
nitrogen contents. On an average it is found that 100 to 125 kg N/ha
becomes sufficient but the mode of application should be same as in
The average uptake of minerals by a corn crop of 5000 kg grain/ha
yield, is 105 kg N, 50 kg P2O5, 75 kg K2O,
10 kg CaO, 10 kg MgO and 6 kg S. In addition micro-nutrients such as
manganese, zinc, boron and copper are absorbed in the order of 100 g/ha.
Plant nutrients can be supplied from different sources viz., organic
manures, crop residues, bio-fertilizers and chemical fertilizers. For
better utilization of resources and to produce crops with less expenditure,
integrated nutrient management is the best approach. In this approach,
all the possible sources of nutrients are applied based on economic
consideration and the balance required for the crop is supplemented
with chemical fertilizers.
Farm yard manure application to the crops is being practiced for long.
Well decomposed FYM in addition to supplying plant nutrients acts as
binding material and improves the soil physical properties. Beneficial
effects of earthworms and their cast were known as early as in Darwin’s
era. But the potential of vermicompost to supply nutrients and to support
beneficial microbes is being recognised recently. Since vermicompost
is rich in humus forming microbes, nitrogen fixers and drying of the
vermicompost has not deteriorated the microbial population. Hence, these
characters recognised the vermicompost as biofertilizer.
At the same time only organics alone do not produce spectacular increase
in the crop yields, due to their low nutrient status. Dependency on
chemical fertilizers alone may not provide a viable economic option.
Therefore to maintain soil productivity on a sustainable basis, an integrated
nutrient management approach, using both organic and inorganic sources
of nutrient should be adopted. In the present context, the use of manures
must be given prime importance and fertilizer use should be limited
to balance the nutrient requirement of the crops. Sustainable yield
could be achieved by integrated use of chemical fertilizers and organics.
Continuous use of crop residues and organics help to build up soil humus
and beneficial microbes besides improvement of soil physical properties.
Whereas, chemical fertilizers provide one or more essential plant nutrients
which the soil can’t supply in adequate quantities. Thus judicious combination
of organics and chemical fertilizers help to maintain soil productivity
maize has high production potential specially under irrigated condition
when compared to any other cereal crop. The productivity of maize is
largely dependent on its nutrient management particularly that of nitrogen.
It is well known that maize is a heavy feeder for nitrogen and demands
150 to 200 Kg N ha-1. In order to sustain soil fertility
and to reap rich harvests of maize, it is imperative that both organic
manuring and mineral nutrition have to be given adequate attention.
Effect of Vermicompost
The vermicompost is an aerobically degraded organic matter which has
undergone chemical disintegration by the enzymic activity in the gut
of worms and so also enzymes of the associated microbial population.
Vermicompost is rich in both macro-nutrients (0.56 per cent N 1.48 per
cent P2O5 and 0.36 per cent K2O) and
micro-nutrients besides having plant growth promoting substances, humus
forming microbes and nitrogen fixers. Recently it has been found that
use of vermicompost in field crops.
Practical implications of the Integrated Nutrient Management
We can reduce 25 per cent of the inorganic nitrogen (37.5 kg/ha) and
phosphorus (18.75 kg/ha) with the application of 12 t FYM/ha and seed
inoculation with Azotobacter chroococcum and Aspergillus awamorii.
The low cost technologies like seed inoculation with Azotobacter
chroococcum (N fixer) and Aspergillus awamorii (P. solubilizer)
may be followed with 100 per cent of the recommended nitrogen and phosphorus
to achieve higher yields and economics.
A leguminous crop like cowpea can be grown with the residual effect
of 75 per cent of the recommended inorganic nitrogen and phosphorus
either through single super phosphate or rock phosphate with 12 t FYM/ha
with or without bio-inoculates for maize.
By following integrated nutrient management (with the application
of P either through single super phosphate/rock phosphate at 112.5 :
56.25 kg N : P2O5 + 12 t FYM/ha with or without
bio-inoculants) higher gross returns, net returns and benefit : cost
ratio can be obtained in maize (summer) and cowpea (Early kharif).