সেউজী
ধৰণী
Organic Farming - Concept
and Reality
DR.BINOY KR. MEDHI1 and DR. RAMANIKANTA THAKURIA2
Introduction
Though, India is proud of its
"Green Revolution" because of four-fold increase in food production
in the last 50 years but this achievement has been followed by protests
degrading environment and human health. The major effect of "Green
Revolution" is that our agricultural system has become chemicalized. The
effects of excessive and hazardous usage of pesticides, herbicides and
fertilizers on human health are because of their high toxic and residual level
in food chain. The chemicalized agriculture, though, has tremendous potential
in production of crop on short term basis but because of its harmful
consequences on human health and eco-system, a movement of alternate form of
agriculture has come forward which is known as "Organic agriculture"
or 'Organic farming". What is "Organic Farming then? Organic farming
means farming in the spirit of organic relationship. The concept of organic
farming bears dubious meaning in the developing countries ('Inorganic +
Organic' and 'solely organic'). In India, it means organic where no synthetic
fertilizers and chemicals like pesticides, herbicides etc. in agriculture are
allowed. Lampkin (1990) defined organic farming as a production system, which
avoids or largely excludes the use of synthetically compounded fertilizers,
pesticides, growth regulators and livestock feed additives. Critical observations
revealed that though the production level achieved through organic farming is
comparatively less then chemicalized farming but the quality and levels of
production in organic farming could be assured in long-term sustained basis
without hampering the surrounding eco-system. But, is it feasible to go for
organic farming to meet the need of the overwhelming population pressure and
socio-economic conditions of our poor farmers? It is a matter of great debate
for the agricultural scientists.
Farmers adoption
As per our farmers perception, the
fertilizer management schedule for any crop or cropping sequences generally
implies the use of easily available fertilizers like Urea, Single Super
Phosphate (SSP) and Muriate of Potash (MOP). In organic farming, the role of
urea to supplement nitrogen, SSP to supplement phosphate and MOP to supplement
potash are to be substituted through any organic sources. Though the organic
materials like concentrated organic manures (Neem Oil Cake, Mustard Oil Cake),
cow dung enriched Farm Yard Manure (FYM), Vermicompost, Green-manuring crops,
Bio-fertilizers and other organic wastes are available but in real practice,
our farmers generally prefer to use cow dung enriched FYM. Moreover, while
practicing the farming totally through organics, some problems in applying the
organic materials in relation to inorganic fertilizers are often encountered in
the practical field situations. The feasibility of applying organics and
inorganic fertilizers are discussed below :
FYM and Inorganic fertilizers
For higher productivity
of any crops or cropping sequences, the optimum dose of readily available
nutrients like Nitrogen (N), Phosphorus (P2O5) and Potash
(K2O) are recommended for a particular type of the soil. Let us
assume that dose for one crop is 40 kg N (87 kg Urea), 20 kg P2O5
(125 kg SSP) and 20 kg K2O (33 kg MOP) per hectare. Now, the
question is how much bulk quantity of FYM is to be incorporated to substitute
the above quantities of fertilizers. It is generally known that FYM contains
0.55% N, 0.19% P and 0.60% K. Out of these, only 30% N, 60-70% phosphate and
75% potash are readily available to the first crop and the rest portions are
likely to be available in the successive crop season or remain as such in the
soil. Therefore, to supplement equivalent quantity of 87 kg Urea per hectare,
24 Mt or rather 24,000 kg of FYM need to be applied in the soil. Is it really
feasible in organic agriculture? Further, after incorporating 24,000 kg FYM per
hectare of soil, the equivalent amount of added SSP and MOP will be 392 kg and
216 kg, respectively, which are again higher (267 kg for SSP and 183 kg for
MOP) then what is recommended for the crop in question. Surprisingly, the
above-calculated quantities are determined based on the partial content of the
total nutrients present in FYM on dry-weight basis. Therefore, to supplement
equivalent quantity of 87 kg urea through FYM, an additional amount of Rs.
1015/- for 267 kg SSP and 851/- for 183 kg MOP per hectare has to be borne. It
appears that in order to equate with one nutrient through FYM, excess nutrients
(imbalance) for the crop in question are applied. On the other hand, if the FYM
is applied based on the K2O requirement of the crop, then to supply
20 kg K2O per hectare, required quantity of FYM will come around 3.7
Mt or 3700 kg. Again, this 3.7 Mt is equal to 13.2 kg Urea and 60.4 kg SSP. In
this case also, no balance quantities of fertilizers are applied or rather the
quantity of fertilizers incorporated are comparatively less (73.8 kg for urea
and 64.6 kg for SSP) than what the crop in question is specifically needed.
Vermicompost and Inorganic
fertilizers
The quality of any vermi-product is
largely determined by the type of raw materials added, but on an average it
generally contains 1.8% N, 1.12% P and 1.55% K. The suggestive limit of
application of vermicompost in most of the field crops is 2 Mt (2000 kg) per
hectare but in most of the horticultural crops (30 X 30 cm spacing) the amount
may go as high as 2.5 to 3.0 Mt per hectare (assuming 30g for each seedling).
Moreover for managing chemical fertilizers (N : P2O5 : K2O
120 : 60 : 120 kg/ha)) and organic manures in most of the horticultural crops,
the cost will come around Rs. 5000/- while, in case of vermicompost application
the figure will be around Rs. 20,000/- (assuming the cost of vermicompost @ Rs.
10/- per kg). Therefore, considering the economic condition of our poor
farmers, is it feasible to apply vermicompost in the practical field situation?
Further, will it be possible to supply all the nutrients to the specified crop
in question by mere application vermicompost? In such situation, what should be
our suggestion to the farming community, whether to go for least-cost higher
production through chemical farming on short term basis or to produce quality
products on sustain basis without compromising the quality through organic
agriculture that involve higher cost of production. These are some of the vital
issues that need to be focused critically.
Green manures and Inorganic fertilizers
Green manure (Sunhemp, Sesbania,
Crotolaria, Dhaincha etc.) serve as reservoir of plant nitrogen associated with
numerous nodulation in their roots as well as in the stems depending upon the
species. Questions generally arise, whether the green manure crops have the
potential to supply all the required nutrients to the succeeding crops? The
answer will certainly be "no". Let us depict the issue by taking a
small example. Suppose a farmer desires to grow one main crop taking Sunhemp as
preceding green manuring crop. The seed requirement of Sunhemp to cover one
hectare of land is approximately 60 kg costing around Rs. 1800/-. Research
findings revealed that biomass production (Dry-matter) of 50 days old Sunhemp
per hectare is 4.6 Mt, which generally accumulate 119.6 kg N, 40.9 kg P2O5
and 106.5 kg K2O. Further, out of these total content, how much
quantity of nutrients become available to the soil or to the immediate crops
will largely depend upon their ratio (C : N, C : P) with total carbon. Wider
the ratio lower will be their availability and vise-versa. It has been
estimated that only 20 per cent of the total nutrients in green manure crops
are available to the first crop. Therefore, it could be inferred that by
spending Rs. 1800/- for purchasing the seeds of Sunhemp, the quantity of
available nutrients like N, P2O5 and K2O added
to the first crop per hectare will be only 24 kg, 8.2 kg and 21 kg,
respectively. On the other hand, if the above-specified quantities of nutrient
are likely to be supplemented through chemical fertilizers say, Urea, SSP and
MOP, one has to spend only Rs. 620/- per hectare. Keeping asides the bulk
quantities of organic matter added to soil, growing of green manure crops in
hectares of land and in-situ chopping to mix well ahead of cultivation of the
main crops are also labour expensive. So, which methods of farming will our
farmers adopt considering their socio-economic condition? It needs to be
studied critically.
Bio-fertilizers and other natural products of Insecticides
Rhizobium, Azotobacter, Azospirillum,
Azolla, Blue Green Algae etc. for supplying nitrogen and PSB (Phosphate
Solubilising Bacteria) and VAM (Vesicular Arbuscular Mycorrhiza) for supplying
phosphate in the soil are generally understood. However, bio-fertilizers that
could supplement potash in the soils are yet to be established. Moreover,
information on quantification of bio-fertilizers to substitute or replace a
unit quantity of chemical fertilizer is meager in most of the crops. One of the
disadvantages while using bio-fertilizer is regarding its short-term
durability. Unlike chemical fertilizers, the prescribed bio-fertilizers in most
of the cases are advocated to use before its expiry date (generally less that 6
months), otherwise, no effective response could be expected. This is because of
living spores present in each bio-fertilizer, which are likely to form damaged
cells with the time.
Among the natural products,
insecticides like 'Bugsac', 'Napthoquinones'; Bactericide like 'Allicin';
Fungicides like 'Strobllurin', 'Pyrrolnitrin' etc are available in the market
but scientifically at what extent such natural products are effective in
controlling the target group of insects, pests and diseases. These need to be
studied thoroughly after considering all the factors that determine their
efficiency.
Future speculation
Considering the pace of population
growth at present rate, it has been estimated that by 2025, India will need to
produce 301 million tones of food grains including other commodities that will
require at least 45 million tones of plant nutrients. Now, is it possible to
supply such a high margin of plant nutrients only by adopting the practice of
"Organic farming"? Nobel Laureate Dr. Norman E. Borlaug has to say on
this issue "We can use all the organic that is available but we are not
going to feed billions of people with organic fertilizers". Organic
farming is an issue of much concern to all because of its serious implication
if it is adopted on large scale primarily of its avowed aim of excluding
application of chemical fertilizers in our agricultural production system.
Though chemical agriculture have some implication in respect of quality of
foods, but in the country like India, reducing the chemical inputs by 25 to 50
percent and substituting them through integration with organic amendments seem
to serve our purpose. The basic concept underlying is the maintenance or
adjustment of soil fertility and plant nutrient supply to an optimum level for
sustaining the desired crop productivity through optimization of the benefits
from all possible sources of plant nutrients in an integrated manner. It has
been established that to cope up with 45 million tones of plant nutrients,
demand of chemical fertilizers would be 35 million tones and rest 10 million
tones should be substituted through organic sources like organic manures, green
manuring crops, bio-fertilizers etc.
Conclusion
There appears from the above
discussion that "Organic farming" could not be taken as the alternate
practice of chemical farming. Partial substitution of chemicalized farming
through organic source or rather integration of inorganic (chemical) plus
organic for optimizing the yield on sustain basis without compromising the
quality of the product would certainly pave the right way to our farming
community. The movement of "Organic farming" laid a big challenge to
the scientific community who would only give some amicable solution based on
experimentally verifiable fact and resist succumbing to any Westernized dogma.
1 Senior Scientist, 2 Chief
Scientist
AICRP on WATER MANAGEMENT, Assam
Agricultural University, Jorhat
