Microorganisms, earthworms enrich the soil

Biofertilisers and earthworms are increasingly being used to replace chemical fertilizers

NATURAL is better than artificial -- at least as far as agriculture is concerned. Chemical fertilisers and pesticides -- though effective to some extent -- have proved to have adverse effects in the long run. With the harm wrought by fertilisers and pesticides, biological pest control and organic farming are being seen as safe because they involve no synthetics. In Tamil Nadu and Karnataka, the demand for microorganisms and earthworms as substitutes for chemical fertilisers is increasing.

Says G S Venkataraman, director of the Centre for Biofertilisers in Madurai Kamaraj University (CBMKU) in Tamil Nadu, "Natural nitrogen fixing systems such as biofertilisers are the only solution to soil degradation wrought by synthetic fertilisers and pesticides."

Biofertilisers -- naturally occurring fertilisers -- are microorganisms that can be introduced into the soil to fix atmospheric nitrogen in a way that can be absorbed easily by plants. Commonly used biofertilisers are blue green algae (bga), Azolla, Rhizobium, Azospirillum and Azotobacter. A study by A Sankaram, a Madras-based agriculturist, shows Anabaena azollae fix 60 kg of nitrogen in one ha of paddy.

"Biofertilisers are not an alternative to chemical fertilisers. But they can enhance the availability of plant nutrients from the soil," says agricultural scientist M S Swaminathan. However, S Shanmugasundaram of CBMKU says, "If farmers use biofertilisers continuously for three years, they will not need synthetic fertilisers again because the microorganisms will get well established in the soil and be able to generate the nutrients needed by the crops."

But there's more to using biofertilisers than just sprinkling microorganisms on a field. Some organic farmers like Julie and Vivek Cariappa of Mysore district say it is not necessary to introduce any organism to healthy soil because "the algae grow naturally". However, Venkataraman argues it may not be possible for farmers to distinguish between good algae and bad algae in the soil.

Swaminathan says "screening of beneficial algae is essential for mass production and application". With this in mind, the department of biotechnology is conducting research on biofertilisers at its centres in Madurai, Delhi, Pune, Lucknow and Calcutta.

The Madurai centre, which is engaged in collection, screening and multiplication of algae, has identified five microorganisms that fix nitrogen efficiently -- Nostoc sp, Aulosira sp, Anabaena sp, Oscillatoria sp and Westiellopsis sp.

Combined use
All of them have been recommended for combined use by farmers because "most of the farmers don't carry out soil tests" (to see which type best suits the soil), according to B Chandrasekaran, director of the Water and Soil Management Centre at Thanjavur. Besides, farmers can get dry powdered algae from the Madurai centre at Rs 2 for a 200 gm packet, instead of the wet algae that they used earlier, facilitating transportation and handling.

In addition to providing nutrients, biofertilisers can increase crop yield. A study conducted by the Tamil Nadu Rice Research Institute in 1992 indicates paddy yields were 20 per cent higher when treated with bga, Aazospirillum and chemical fertilisers, than when treated with bga and Azospirillum alone or with chemical fertilisers alone. Inspired by this, K Subramaniam Vandayar, who owns a 14-ha plot in Vadayaryiruppu village of Thanjavur district, has been using 100 kg of biofertilisers with 50 tonnes of dung and 100 kg of chemical fertiliser on a one-ha plot of paddy. He hopes to bag the district's highest yield award this year.

Biofertilisers are, however, not yet very popular in Tamil Nadu. D Subramanian, a Bangalore-based field officer with the Indian Farmers Fertiliser Cooperative Limited (IFFCO), blames it on poor marketing. "The design and packaging of biofertilisers has to be eye-catching. Besides, there are hardly any advertisements."

But in Thanjavur district, government agencies are unable to meet the demand for biofertilisers. Says S Kunjithapatham, joint director in Tamil Nadu's department of agriculture, "Only 10 per cent of the demand is met by government agencies. In 1993, (from July to October) only 160,000 packets of 200 gm each were supplied in Thanjavur's rice belt, against a demand of 2 million packets." He cautions that private entrepreneurs might step in and sell sub-standard products.

Demand for vermicompost
In stark contrast to the restricted demand for biofertilisers, vermicompost is becoming increasingly popular in neighbouring Karnataka state. Says Bangalore-based vermiculturist K N Ganesh, "The demand for both earthworms and vermicompost is growing sharply and we are unable to meet it."

Ratha D Kale, head of the zoology department of Bangalore's University of Agricultural Sciences (UAS), which sells earthworms and vermicompost, says, "The increasing demand has forced us not to give more than 100 worms to each buyer. Vermicompost users will have to breed worms, too."

UAS sold 150,000 worms and three tonnes of vermicompost in 1992 -- at Rs 10 per 100 worms and Rs 2,000 per tonne of compost -- to 444 people, of which 105 were from Bangalore alone. Kale says the spurt in demand is because vermicompost is increasingly seen as an eco-friendly substitute for chemical fertilisers and is used in urban kitchen gardens and rural fruit orchards. Scientists and NGOs, too, have shown a keen interest. According to UAS zoologist N S Sunitha, vermicompost contains five times more nitrogen, seven times more phosphate and 11 times more potash than the given top soil.

Some farmers not only use earthworms, they also sell them. R S Patil, a farmer in Karnataka's Dharwad district, started vermiculture in 1990 and sells a box of 1,000 worms for Rs 250. Earthworm droppings fetch Rs 3,000 per tonne. Every ha of wetland needs at least 2.5 tonnes of earthworm compost per season. Patil's clientele consists of rich, local farmers.

In cities like Bangalore, people pay Rs 7 per kg of vermicompost, though if bought in bulk, the price is Rs 6,000 per tonne. Prompted by the increasing demand, B S Shashikumar, a vermicompost producer of Bangalore, plans to hike the price to Rs 10 per kg. Ganesh says there is a huge demand even for dead worms, which are used as poultry and fish feed.

There are more than 200 varieties of earthworms in India, but only three species are popular -- Eudrilus eugeniae and Perionyx excavatus for tropical conditions and Eisenia fiteda for temperate conditions as they are more suited than the others for these climatic conditions. But K Gunathilagaraj, professor of environmental sciences at the Tamil Nadu Agricultural University (TNAU) in Coimbatore, says, "No research on earthworm species, the rate of their conversion of organic matter or their reproduction patterns has been done so far."

Vermiculture, especially feeding the worms, is a delicate business. This is more so in urban areas, where glass shards often get mixed with compost, says Patil. But Bangalore-based entrepreneurs disagree. Says Ganesh, "We don't have any problems collecting urban refuse. People are very happy to give us their vegetable peelings and we feed the worms almost free." Ganesh has made arrangements to collect the garbage in his area regularly and the people support him as they see it as a way to a cleaner environment. However, Gunathilagaraj warns against unscientific vermiculture. He says, "Studies in Tamil Nadu's Kanyakumari district and Karnataka's Hassan district show earthworms can damage paddy and cotton crops. Their droppings tighten the soil around paddy roots, depriving the crop of moisture.Earthworms also carry Anthrax beetle pathogens, which attack cotton."

To overcome this, M V Nadkarni, professor of ecological economics at the Institute for Social and Economic Change in Bangalore, suggests factory farming of earthworms "so that the essentials of health and hygiene are ensured".