Agripedia

Organic Agriculture: Need & Importance

After a tumultuous use of chemical fertilizers during the periods of green revolution in most of the parts of the world, people have come to realize that constant use of fertilizers do harm in the long run. How such an unexpected harm took place can be best understood if we can compare it with the use of allopathic medicines in our life without proper food intake. Most of the time doctors would advise the patients to take the medicines only after taking a meal. Exactly the same principle holds good in the case of the use of chemical fertilizers and organic manures: chemical fertilizers take the place of allopathic medicines and organic manures take the place of balanced and sufficient food intake.

Difference between fertilizers and manures

The most important question that comes into the mind of everyone is what is a difference between the fertilizers and manures?  In a commonsensical language they can be understood as: chemical fertilizers contain one or two plant nutrients in concentrated form whereas the organic manures contain most of the plant nutrients in very small amounts just as allopathic medicines are concentrated forms of one or two human nutrients in one form of chemical like urea contain nitrogen (45% N), superphosphate contain phosphorus (24% P) and potash contain potassium ( 70% K) while the balanced diet contains all the nutrients as they comprise of various food items like wheat/rice, pulses/dals, milk, egg, three kinds of vegetables (leafy, root and immature fruits and pods) which have high or low amount of nutrients of all types required for the body. In the same way, organic manure is composed of all kinds of bio-materials such as leaves, animal dung, crop residues, waste food, waste from the fish market and slaughterhouses, vegetable and fruit wastes etc. 

Importance of organic manures

Next question is, what is the importance of organic manures and organic farming? To understand the answer to this question we need to understand the physical and chemical nature of the normally cultivable soil. Physically the soil consists of mineral or rock particles of various sizes harbouring the microscopic sized humus dusts, soil moisture and various soil gases and numerous macro and micro-organisms: all making up a lump soil like a compact sponge. Just like a sponge a lump of soil has an apparent or virtual volume and a compressed, actual or solid volume. Again like sponge the expanded or virtual volume of the soil is useful to the human beings and specifically to the farming people. Then further question is, what is the percentage of the volume of the above mentioned components in the apparent or virtual volume of the soil? Under normal cultivable circumstances about 45% consists of mineral or rock particles, 5% organic matter consists of humus and living micro and macro-flora and fauna, 25% volume each consists of the apparent volume consists of soil moisture and soil gases.

Constituents of soil

Chemically soil consists of almost all the elements found in the periodic table either as compounds or elemental form and depending on the excessiveness of one or other elements in a given soil its chemical properties will be defined. Hence we have acidic and alkali soils. Depending on the percentage of air volume we have the hard and compact soils or loose and light soils. Depending on the moisture content we have very dry and hard soils to lose and easy to work type of soils with good tilth. Finally depending on the organic matter, the soil can vary from fertile to unproductive soil. Though the organic matter in a normal cultivable soil is on an average is only around 5% its influence on the productivity of the soil is very high. 

Role of organic matter

Then what is the role of organic matter in the soil? This question is best answered by quoting a saying, “Organic matter is the soul of the soil”. A soil with zero organic matter is like a dead body of a human being totally incapable of doing any productive work.  Narrowing down further we can say that it is the hummus part of the organic matter that is the “essence of the soul of the soil”.

Organic matter is the soul of the soil and
Humus is the essence of the soul of the soil.

The organic manure is a concentration of humus-forming organic matter available in the nature in the form of decomposed plant or animal wastes like animal dung,  human feces, fish and slaughterhouse wastes, decomposed leaves and crop residues and biologically degradable kitchen household wastes. In the virgin forests, the top-soil mixed with a large amount of decayed and decomposed leaves can consider as a soil highly rich in organic manure. Similar organic manure can be produced from all the bio-waste generated every day around us whether we live in a rural or urban area. These organic manures when incorporated into the soil it becomes the real food for the soil and the soil becomes strong and productive like a human body with a productive mind. Organic manure should well decompose or well rotten in the sense that all the decomposition process should be complete it is applied to the soil before the final preparation of the land for sowing the seeds or planting the crops.

Dosage of organic manure

How much should organic manure be added to the soil per crop cultivated crop or per year?  It can vary from crop to crop and soil to soil. For heavy yielding crops like tomato, sugar cane, maize, jowar, cabbages, cauliflower, elephant foot yam and another yam etc. apply 3 kg of organic manure per square metre which means 30,000 kg per hectare or 12,000 kg per acre.  But the minimum amount should be 10,000 kg per hectare or 4000 kg per acre.  Poorer the soil greater the amount of organic manure to be applied for a number of years till it has a minimum 5% organic matter in it. Care should be taken all the organic manure applied should be incorporated into the soil by ploughing or harrowing.

What is the problem in applying the above mentioned rate of organic manure? The sheer quantity and the volume of the organic manure required to be handled and the huge cost in terms of its price and labour cost is the main hurdle in using such an amount of organic manure. Secondly the availability of such an amount of well rotten organic manure is very rare. Thirdly the available manure especially is not a well one. For example 90 per cent of the cowdung or the farm yard manure applied by farmers in the villages are not well rotten or well decomposed. Hence they are eaten up by the white ants coming from outside or are already settled in the cropping plots. At the same time several farmers apply just dried up cowdung or farm yard manure into the field. They all go waste.

Apply only well rotten organic or manure at the rate 30,000 kgs per hectare or 3 kg per square metre to maintain the full productivity of the soil

Generation of organic manure

How to generate such huge amount of organic matter is the next question people ask. Again to understand the answer for this question we need to understand the productivity of organic matter in a unit area of one hectare or acre. Leave any land of one hectare in a normal rainfall area fallow one year and allow all types of grasses and shrubs to grow. If you want just sow the seeds of any fodder crop or green manure crop. After one year take sample cutting of the whole plant in one square metre area from ten randomly selected spots from the plots. Weigh them fresh and estimate the total weight of cut vegetation from 100 square metre sampling area. It will be around 900 kgs which means one square metre can generate about 3 kg of organic matter. The same when decomposed we may get about half to one kg of organic manure. The same when applied back into the same area next year the harvested yield from the same plot will be about 5-6 kg per square metre. Again the same is decomposed and applied back into the soil and subsequent crop will yield 9-10 kg per square metre. Thus properly recycling almost all the organic matter generated in a given area we can build up the organic matter content in the soil.

Incorporate all the organic matter generated in a
plot or area back into the same plot or area.

Never burn anything organic

What does it imply? It implies that nothing of any organic matter should be burned in any field. Unfortunately burning all the crop residues and cowdung is a practice going for many centuries in many parts of the world especially in India. By burning the organic materials we lose all the organic matter from the soil. When burning is practiced successively every year the soil in the cropping field gets exhausted of whatever organic matter it had and the soil becomes unproductive and useless. Eventually that land becomes a wasteland. Therefore begin a movement of composting all the organic matter generated in the form of crop residues or animal dung. Prepare a few composting structures in every cropping field or plot and dump all the crop residues after chopping into small pieces. The placing chopped pieces should done in layers interspaced with fresh cow dung or cowdung slurry and soil. Make sure there is sufficient moisture in the mixture. It takes one to one and half years for the crop residues to decompose. Hence at least there should be two or three structure in every cropping plot. For technical information will be given in the following section of this article.

Never burn anything of organic matter generated
in any crop filed or animal farm.
Burning of any organic material is the most harmful practice against
Agriculture and Environment.

Liquid organics

The organic manure is not only in the solid form but also in the liquid form. The most common liquid forms of organic manures are: slurry from the bio-gas plants, urine of animals, bathing and dish washing water, other waste liquid from cooking and cleaning of food items before and after cooking, sewage and sullage. The leachate from well prepared composting structures can be most rich type of organic liquid manures. While composting numerous water-based decompositions takes. As a result a lot of liquid comes out in the form of leachate rich in plant nutrients. Before applying bio-gas slurry and leachates from composting structures, they should be diluted to four or five times before applying it into the field. It can be best applied by incorporating into the controlled irrigation water.

 

Preserve and apply all the available
liquid organic manures also into the field. It will supply
both organic manure and moisture to the soil.
That is the way to build up organic matter in the soil
and also to build up the Environment.

 Concluding remark

Application of organic manures is as important as we take a balanced meal before we take the allopathic medicines. We need to take allopathic medicines in the prescribed, smaller quantities whenever we need. So too we have to apply the chemical fertilizers in the proper prescribed amounts whenever needed. Never burn anything of the organic materials around but compost them in suitable structures in the crop field itself. That is the way to generate the required organic manure for each farmland. Use all available liquid forms of organic manures also.


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