Sunday 26 January 2014

Organic Farming - Concept and Reality




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.



 Senior Scientist, Chief Scientist
AICRP on WATER MANAGEMENT, Assam Agricultural University, Jorhat
For correspondent: 09954149527: ID: binoykrmedhi@gmail.com

         



1 comment: