The
rate of growth of agriculture in its broad coverage nf crop production is much
below the national growth rate. If the economy of country is to be improved
through agriculture, it has to strengthen its programmes in such a manner to
better utilize the natural resources along with balanced use of chemical
fertilizers and other inputs. We are aware that for increasing the food
production to fulfill the food requirements of the burgeoning population of
the country sustainability of agriculture and environmental safety are the
priority issues. To avoid wastage of precious national resource and to
minimize the environmental damage there is need develop and demonstrate
balanced use of chemical fertilizer. This will not only improve the crop
production in sustainable way but also economize the crop production. Higher
food production needs higher amount of plant nutrients. As no single source is
capable of supplying the required amount of nutrients, integrated use of all
sources is a must to supply balanced nutrition to plants.
What is balanced nutrition
Balanced
fertilization does not mean a certain definite proportion of nitrogen,
phosphorus and potash or other nutrients to be added in the form of
fertilizer, but it has to take into account the availability of nutrients
already present in the soil, crop requirement and other factors. It should
take into account the crop removal of nutrients, the economics of fertilizers
and profitability, farmers ability to invest, agro-techniques, soil moisture
regime, weed control, plant protection, seed rate, sowing time, soil salinity,
alkalinity, physical environment, microbiological condition of the soil,
available nutrient status of soil, cropping sequence, etc. It is not a state
but a dynamic concept.
We
can say that balanced use of fertilizers should be mainly aimed at :
(a)
increasing crop yield, (b) increasing crop quality, (c) increasing farm
income, (d) correction of inherent soil nutrient deficiencies, (e) maintaining
or improving lasting soil fertility, (f) avoiding damage to the environment,
and (g) restoring fertility and productivity of the land that has been
degraded by wrong and exploitative activities in the past.
Balanced
use of plant nutrients corrects nutrient deficiency, improves soil fertility,
increases nutrient and water use efficiency, enhances crop yields and farmers
income, betters crop and environmental quality. To reap the benefits of
balanced use of plant nutrients, it is important to have good quality seed,
adequate moisture and better agronomic practices with greater emphasis on
timeliness and precision in farm operations.
Soil
testing is one of the most important tools to practice balanced fertilization.
Balanced fertilizer rates differ from area to area and also from crop to crop.
Through soil testing farmers can know how much and what kind of fertilizer to
use for each crop. A further refinement in fertilizer dose is possible on the
basis of type of crop and its variety, water availability and its quality,
availability of organic manures, crop residues, biofertilizers, etc.
Since
the initiation of green revolution in late sixties, India has made a
remarkable progress in fertilizer nutrient use with the introduction of high
yielding varieties of wheat and rice. Crop production under intensified
agriculture over the years has resulted in large scale removal of nutrients
from the soil, resulting in negative balance and declining soil fertility.
Organic
sources are undoubtedly an important source of nutrients but their amounts and
available nutrient content and the release rate is woefully inadequate for
meeting the demands of intensive and high yielding crop production.
India
is presently using 15 mt of nutrients in the form of chemical fertilizers.
Supplying the same through organic sources would require more than a thousand
million tones, which is an impossible task indeed. Such organic manures in
monumental volumes are neither available nor can be generated. Thus organic
sources of nutrients can only be relied upon on meeting parts of the nutrients
needs of the crop. They should be added along with chemical fertilizers for
ensuring stability and sustainability of food production.
In
India fertilizer consumption increased from less than 50,000 tonnes in 1950 to
15 million tones in 2000 and the food grain production increased from 50 mt to
200 mt in the same period, indicating a direct relationship between the
fertilizer use and yield increase. The green revolution or spectacular
increase in production would not have been possible without many fold increase
in use of fertilizers. The high yielding varieties became a catalyst for the
conversion of chemical energy into biological productivity. We have not yet
realized the full potential of these varieties. Even the optimum potential of
available technology remains mostly unrealized in most regions as nutrient
input does not match the needs of the crop and soil.
There
are vast differences in consumption of fertilizers per ha of cropped area in
different regions. The fertlizer consumption varies from 114, 103, 58, 47 kg (NPK)
per ha cropped area in north, south, east and west respectively. Some states
like Punjab are using more than 167 kg nutrients per ha as against some using
less than 10 kg nutrients per ha. About 70 – 80 per cent fertilizer is used
for growing rice and wheat. Besides these the major recipients of the
remaining fertilizer use are sugarcane, cotton, potato, plantation and
horticulture crops. The lowest fertilizer use is in rainfed farming, which
covers nearly 66 per cent of the total cropped area in the country. It hardly
needs to be stressed that in these rainfed areas more from deficiency than
moisture inadequacy. But the later is more appreciated than the former.
There
are also wide differences in the consumption ratio of three major nutrients N
: P2O5 : K2O in different regions, crops and
cropping systems. These differences also got magnified and showed aberrations
due to adhoc changes in pricing policy of fertilizers during the recent years.
This and the NPK ratio for India changed from 5.9 : 2.4 : 1.0 in 1991-92 to
9.7 : 2.9 : 1.0 in 1993-94. There is also divergence in ratios in different
regions. While the ratio in 1995-96 was 41.4 : 8.5 : 1.0 in northern states
and 3.8 : 1.4 : 1.0 in southern states. Such divergence in new ratio is also
due to the differences in the quality of land, inherent soil fertility,
cropping systems and degree of exploitive agriculture.
Soil
test summarizes indicate that 98 per cent Indian soils have low to medium
available P and 60 per cent medium K status whereas, N continues to be
universally deficient. 47 per cent soils are deficient in Zn, 12 per cent Cu
and 4 per cent in Mn. In some states and crops the deficiency of B and Mo are
also becoming limiting factors for crops production. In recent years a
phenomenal increase in S deficiency has been witnessed specially under
intensive cropping system where high analysis fertilizers devoid of S are
used. The S deficiency is more pronounced in crops like oil seeds, legumes and
intensively fertilized rice and wheat. Infact, the spectrum of S deficiency is
increasing so rapidly that in future it will become on of the major yield
limiting factors. It is said that the planners are more concerned with the
yield barriers of some high yielding varieties but do not seem to be concerned
with the rapidly changing scenario of plant nutrient deficiency and the
pivotal role of fertilizers in food security. Thus in a situation where
besides NPK the nutrients such as Zn, Fe, Mn, Cu, B and S are also becoming
limiting factors, It is unthinkable to have a sustained food security without
balanced and integrated use of nutrients from external sources. The spectrum
of nutrient deficiency is becoming more apparent under areas of intensive
cropping systems which are the main contributors of National food stock of
Food Corporation of India. There are signs of yield stagnation and low
responses to fertilizers and other inputs because of imbalanced fertilizer
use.
Nitrogen
no doubt is the most limiting factor for Indian agriculture, but nitrogen
alone is not enough and fertilizer does not mean nitrogen fertilizers only.
Lack of this appreciation has led to poor results in most cases. Improving N
use efficiency is the major problem for improving economy of its use specially
in rice growing areas.
Green
manuring with legumes and other means of biological nitrogen fixations such as
through Blue Green Algae , Azolla, etc. can contribute to some of the N needs
of rice crop but there are numerous technological, economic and operational
problems to their use. At best they can be relied upon for 30 – 60 kg supply
under good management. The efficiency of use of biofertilizers is more crop
specific, location specific and management specific and unless there is a
reliable system of quality control and a good system of storage,
transportation and management in the field, the expected contribution will not
be realized.
No
doubt the awareness of balanced use of fertilizers is growing, but enormously
wide N : P : K ratio are a matter of great concern. It is amazing that NPK
ratios in Haryana during 1995-96 was 186 : 42 : 1 as against 64 : 14 : 1 in
Punjab and 1.9 : 0.6 : 1 in Tamil Nadu as against 8.9 : 2.8 : 1 in whole of
India. Bringing this ratio closer to the desirable ratio of 4 : 2 : 1 for
cereals is essential for maximizing the efficiency of fertilizers. The matter
is more urgent lest in the long run, disappointingly low yields result. The
situation of P and K is more worrisome in India.
The
declining use efficiency of fertilizers and of soil productivity are other
matters of concern. This fatiguing effect is more prominent in frontier states
of green revolution such as Punjab, Haryana, U.P. and other intensively
cropped areas of the country. It has been estimated that annually we are
robbing the soil of more nutrients in the form of biomass than returning to it
in the form of fertilizer and manures. The annual negative balance seems to be
of the order of about 10 mt of NPK. It will become manifold when we attempt
doubling the productivity and production. If this nutrient drain continues,
the sustained high productivity and sustainability of agriculture will be an
impossible task.
India
is adding every year population to one Australia and New Zealand and it is
estimated that by 2025 the population of the country will touch 1.4 billion
mark. For feeding such a large population, India may need about 300 million
tones of foodgrains annually. It may require 35-45 mt of nutrients from both
organic and inorganic sources of fertilizers. Besides these it will also need
thousand tones of Zn, Fe, Mn, Cu and B.
It
is not only the huge amounts of fertilizer nutrients which matters but also
the use efficiency and management system which will determine their economics
or benefit/ cost ratio is equally important. Thus the key to future national
food security and national security lies in balanced and integrated supply and
management system, and there is no alternative to it. Balanced fertilizer use
is also necessary to improve the economics or profitability of fertilizer use
which provides incentive to farmer for its efficient use. It also improves the
quality of the produce which is very much in demand for the export market as
well as for home market. It hardly needs to be stressed that many wrong
notions about fertilizer use spoiling the soil quality are related to
imbalanced and imprudent use of nitrogenous fertilizers only.
No
single source of plant nutrient, whether it is chemical fertilizer or organic
manure or green manure or biofertilizer or crop residue is in a position to
meet the growing crop nutrient need. Moreover, the right kind of nutrients
required by the crop crops may not be achieved from a single source. For
example different chemical fertilizers can supply the nutrients like N, P, K,
Zn and S; Green manuring use can meet a part of nitrogen requirement, one
tonne organic manure can add about 12 kg NPK and also some micronutrients;
crop residue like rice straw is a good source of potassium and use of
biofertilizers can supply nitrogen @ 20-25 kg/ha and mobilize soil phosphorus.
This implies that integrated use of plant nutrients is essential mainly for
two obvious reasons (i) to increase nutrient supply and (ii) practice balanced
fertilization. In addition integrated use of different sources of plant
nutrient helps to increase their efficiencies and also crop productivity.
All
out efforts should be made to educate farmers to practice balanced use of
fertilizers. Of late, some fertilizer companies and associations have come
forward to educate the villagers, publication of literature in regional
languages related to balanced use of fertilizers for higher crop yields in a
sustainable way. The actual time has come, the farmers, researchers and other
related communities should come forward and act in this respect. The chemical
fertilizers should be used judiciously and use manures along with chemical
fertilizers for improving the crop yield and soil productivity in a
sustainable way. Many more activities are being planned to promote the
balanced use of fertilizers. And it is hoped that all these efforts would lead
to desired awareness and as a result balanced fertilizer use would become a
reality in near future.
