Major components of organic farming are crop rotation, maintenance and enhancement of soil fertility through biological nitrogen fixation, addition of organic manure and use of soil microorganisms, crop residues, bio-pesticide, biogas slurry, waste etc. Vermiculture has become a major component in biological farming, which is found to be effective in enhancing the soil fertility and producing large numbers of horticultural crops in a sustainable manner. The various components of organic farming have been discussed in details below:

1. Crop rotation:
It is a systematic arrangement for the growing of different crops in a more or less regular sequence on the same land covering a period of two years or more. The selection of optimal crop rotation is important for successful sustainable agriculture. Crop rotation is very important. Soil fertility management, weed, insect and disease control. Legumes are essential in any rotation and should 30 to 50 percent of the land. A mixed cropping, pasture and livestock system is desirable or even essential for the success of sustainable agriculture.

2. Crop Residue:
In India there is a great potential for utilization of crop residues/ straw of some of the major cereals and pulses. About 50% of the crop residues are utilized as animal fed, the rest could be very well utilized for recycling of nutrients. Adequate care is required to use the residues after proper composting with efficient microbial inoculants. While the incorporation of crop residues e.g. Wheat and Rice straw, as such or inoculated with fungal species had beneficial effects on crop yields and important in physico-chemical properties of soil.

3. Organic manure:
The organic manure is derived from biological sources like plant, animal and human residues. Organic manure act in many ways in augmenting crop growth and soil productivity. The direct effect of organic manure relates to the uptake of humic substances or its decomposition products affecting favourably the growth and yield of plants. Indirectly, it augments the beneficial soil microorganisms and their activities and thus increases the availability of major and minor plant nutrients.

a) Bulky organic manure: It generally contains fewer amounts of plant nutrients as compared to concentrated organic manure. It includes FYM, compost and Green manure.

• FYM: It refers to the well-decomposed mixture of dung, urine, farm litter and left over or used up materials from roughages or fodder fed to the cattle. The waste material of cattle shed consisting of dung and urine soaked in the refuse is collected and placed in trenches about 6 m long, 2 m wide and 1 m deep. Each trench is filled up to a height of about 0.5 m above the ground level and plastered over with slurry cowdung and earth. The material is allowed to decompose undisturbed 3-4 months for anaerobic microorganism for completion of fermentation. FYM becomes ready to apply after 3-4 months. Well-rotted FYM contains 0.5% N, 0.2% P205 and 0.5% K2O.

• Compost: Large quantities of waste material are available as vegetable refuse, farm litter, such as weeds, stubble, bhusa, sugarcane trash, Sewage sludge and animal waste in houses and in areas like human and industrial refuse; therefore, excreta can be converted into useful compost manure by conserving and subjecting these to a controlled process of anaerobic decomposition. Compost is used in the same way as FYM and is good for application to all soils and all crops.

• Green Manuring: It is a practice of ploughing or turning into the soil undercomposed green plant tissues for the purpose of improving physical structure as well as fertility of the soil. From the time immemorial the turning in a green crop for improvement of the conditions of the soil has been a popular farming practice. Green Manuring, wherever feasible, is the principal supplementary means of adding organic matter to the soil. It consists of the growing of quick growing crop and ploughing it under to incorporate it into the soil. The green manure crop supplies organic matter as well as additional nitrogen, particularly if it is a legume crop, which has the ability to fix nitrogen from the air with the help of its root-nodule bacteria. A leguminous crop producing 25 tones of green matter per hectare will add about 60 to 90 kg of nitrogen when ploughed under. This amount would equal an application of 3 to 10 tones of FYM on the basis of organic matter and its nitrogen contribution. The green manure crops also exercise a protective action against erosion and leaching. The most commonly used green manuring crops are: Sunhemp (Crotalaria juncea), Dhaincha (Sesbania aculeata), Cluster bean (Cyamopsis tetragonoloba), Senji (Melilotus parviflora), Cowpea (Vigna catjang, Vigna sinensis), Berseem (Trifolium alexandrium).

b) Concentrated Organic Manure: Concentrated organic manures are those materials that are organic in nature and contain higher percentage of essential plant nutrients such as nitrogen, phosphorous and potash, as compared to bulky organic manures. These concentrated manures are made from raw materials of animal or plant origin. The concentrated organic manures commonly used are oilcakes, blood meal, fishmeal, meat meal and horn and hoof meal.
4. Waste:

1. Industrial waste: Among the industrial by products, spent wash from ditilisers and molasses and pressmud from sugar industry have good manurial value. It is important to use only well decomposed pressmud at 10 tones/ha. Addition of pressmud improves the soil fertility and enhances the activity of microbes. Coir waste is the by-product from coir industry and can be used as manure after proper decomposition.
2. Municipal and Sewage waste: It also forms an important component of organic waste. In India, the total municipal refuse is about 12 mt/annum containing about 0.5% N, 0.3% P2O5 and 0.3% K2O. Sewage sludge is available to an extent of 4 million tones per annum containing 3% N, 2% P and 0.3% K (Bharadwaj and Gaur, 1985). Sewage sludge particularly from industrialized cities is contaminated with heavy metals and these pose hazards to plants, animals and human beings. Separation of the toxic waste at the source will minimize the concentration of such elements in the sludge.

5. Biofertilizers:
It has been observed that there is decline in crop yield due to continuous apply of inorganic fertilizers. Therefore, increasing need is being felt to integrate nutrient supply with organic sources to restore the health of soil. Bio-fertilizer offers an economically attractive and ecologically sound means of reducing external inputs and improving the quality and quantity of internal sources. Bio-fertilizer is microorganism's culture capable of fixing atmospheric nitrogen when suitable crops are inoculated with them. The main inputs are microorganisms, which are capable of mobilizing nutritive elements from non-usable form to usable form through biological process. These are less expensive, eco-friendly and sustainable. The beneficial microorganisms in the soil that are greater significance to horticultural situations are biological nitrogen fixers, phosphate solubilisers and mycorrhizal fungi.

The Biofertilizers containing biological nitrogen fixing organism are of utmost important in agriculture in view of the following advantages:
• They help in establishment and growth of crop plants and trees.
• They enhance biomass production and grain yields by 10-20%.
• They are useful in sustainable agriculture.
• They are suitable organic farming.
• They play an important role in Agroforestry / silvipastoral systems.

Types of Biofertilizers: There are two types of bio-fertilizers.

1. Symbiotic N-fixation: These are Rhizobium culture of various strains which multiply in roots of suitable legumes and fix nitrogen symbiotically. Almost 50% demands of N are met by these microorganisms in legumes.
• Rhizobium: It is the most widely used biofertilizers, which colonizes the roots of specific legumes to form tumours like growths called rot nodules. It is these nodules that act as factories of ammonia production. The Rhizobium legume association can fix upto 100-300 kg N/ha in one crop season.

2. Asymbiotic N-fixation: This includes Azotobacter, Azospirillium, BGA, Azolla and Mycorrhizae, which also fixes atmospheric N in suitable soil medium. They grow on decomposing soil organic matter and produce nitrogen compounds for their own growth and development, besides that they leave behind a significant amount of N in surroundings.
• Azotobacter: Application of Azotobactor has been found to increase the yields of wheat, rice, maize, pearl millet and sorghum by 0-30% over control. The beneficial effect of Azotobactor biofertilizers on cereals, millets, vegetables, cotton and sugarcane under both irrigated and rainfed field conditions have been substantiated and documented (Pandey and Sushil Kumar, 1989). Apart from nitrogen this organism is also capable of producing antibacterial and anti-fungal compounds, hormones and siderophores.
• Azospirillium: It is an important bacterium, which colonize the root zones and fix nitrogen in loose association with plants. The crops which response to Azospirillum is maize, barley, oats, sorghum, pearl millet and forage crop. Azospirillum applications increase gain productivity of cereals by 5-20%, of millets by 30% and of fodder by over 50%.
• Blue Green Algae: The utilization of blue-green algae as biofertilizers for rice is very promising. Recent researches have shown that algae also help to reduce soil alkalinity and this opens up possibilities for bio-reclamation of such inhospitable environments.
• Azolla: A small floating fern, Azolla is commonly seen in low land fields and in shallow fresh water bodies. This fern harbours blue-green algae, anabaena azollae. The Azolla anabaena association is a live floating nitrogen factory using energy from photosynthesis to fix atmospheric nitrogen amounting to 100-150 kg N/ha/year from about 40-64 tones of biomass (Hamdi, 1982; Singh, 1988).
• Mycorrhizae: Mycorrhizae are the symbiotic association of fungi with roots of Vascular plants. The main advantage of Mycorrhizae to the host plants lies in the extension of the penetration zone of the root fungus system in the soil, facilitating an increased phosphorous uptake. In many cases the Mycorrhizae have been shown to markedly improve the growth of plants. In India, the beneficial effects of Vascular-arbuscular Mycorrhizae (V AM) have been observed in fruit crops like citrus, papaya and litchi. Recent studies showed the possibility of domesticating Mycorrhizae in agricultural system (Hayman, 1982; Tilak, 1987).

6. Bio-pesticide:
Bio-pesticides are natural plant products that belong to the so-called secondary metabolites, which include thousands of alkaloids, terpenoids, phenolics and minor secondary chemicals. These substances have usually no known function in photosynthesis, growth or other basic aspects of plant physiology; however, their biological activity against insects, nematodes, fungi and other organisms is well documented.
Botanical insecticides are ecologically and environmentally safer generally affect the behaviour and physiology of insects rather than killing them. Among the botanical pesticides investigated. Neem (Azadirachta indica) has justifiably received the maximum attention. All parts of the Neem tree possess insecticidal property but seed kernel is most active.
Biopesticides and other preparations of plant origin used in agriculture seem to have a good scope especially in view of the environmental problems being faced with the synthetic agrochemical. Some of the commonly used botanical Insecticides are Nicotine, Pyrethrum, Rotenone, Subabilla, Ryanin, Quassia, Margosa, Acorus etc. Their used need to be promoted under the Integrated Pest management Programmes.

7. Vermicompost:
It is organic manure produced by the activity of earthworms. It is a method of making compost with the use of earthworms that generally live in soil, eat biomass and excrete it in digested form. It is generally estimated that 1800 worms which is an ideal population for one sq. meter can feed on 80 tones of humus per year. These are rich in macro and micronutrients, vitamins, growth hormones and immobilized microflora. The average nutrient content of vermicompost is much higher than that of FYM. It contains 1.60% N, 5.04% P2O and 0.80% K2O with small quantities of micronutrients. Application of vermicompost facilitates easy availability of essential plant nutrients to crop.

Preparation: Preparation of vermicompost has been described by Purkayastha and Bhatnagar (1997). A tank of 4 x l x l m is constructed with brick line in a shaded place. The bottom of the tank (about 5.0 cm) is made up of pieces of brick, stone chips and sand. This will facilitate easy drainage of water. Soil is spread over this to a thickness about 15cm. About 4-5 kg of diluted dung may also be applied. About 100 numbers of locally available worm species are placed over the vermibed. It should be moistured without flooding. A layer of (about 10 cm) straw, leaves of plants, kitchen waste etc are spread over this layer. This can be continued till the bed is completely filled. Liquid cowdung suspension is then applied and waste paper and bigger leaves are used to cover the contents in the tanks and finally the tank is fully covered with a gunny cloth. Watering the tank is very important nutrient sources in building up the soil fertility. Cowdung is an input in Biogas plants. The Biogas route has the dual advantage of providing both fuel (gas) and fertilizer (slurry). The residual slurry that comes out of the digestion tank has a manurial value superior to that of FYM. The wet slurry should not be used as such; it should be dried for usage as manure.

Conclusion: A large fraction of farm by-products of plant and animal origin is utilized for non-farm use i. e. for fuel or other domestic purposes. Small and scattered lands holding of the large farming community compel them to leave the crop residue in the farm itself rather than recycle it for recycling. Lack of location specific technology to recycle organic waste and lack of awareness to recycle organic waste in agriculture are the main reason for its slow adoption even though is a native technique for the farmers which got lost during the period of Green Revolution. So, in order to popularize this eco-friendly farming practices like organic farming we have to give attention to strengthen the production of good quality organic manure, bio-pesticides, biofertilizers and green manuring crops, discourage the indiscriminate use of inorganic fertilizers and pesticides, development of pesticides of plant origin (such as Neem) and use of agents especially under integrated Pest Management system as well as steps to reduce hazardous chemical residues in seeds, fodder, food products and milk.

Source:
http://megapib.nic.in/org_farm_comp.htm