Cattle dung is not waste but an asset in rural India. With its use in food production diminishing, biogas is the next best way to utilise it.
Loknath Nauri comes home with a large herd of cattle. He had taken them out for grazing in the forest. But surprisingly most of them are not in milk. “Only one of these gives milk and that too is mostly consumed by the calf,” says Nauri in a genteel voice. He knows there’s more to this herd than milk. Besides being collateral during hard times, it is kept for the dung which is used in the fields as natural fertiliser. However, what is true for Konadiguda village of Odisha is not holding for many parts of India today.
Chemical fertilisers have made inroads in rural India, reaching even the remotest of areas, thus impacting the practice of recycling the cattle dung for food production in a big way. The livestock population in India was 512.05 million in 2012. Of this around 60 percent (299.98 million) were bovines.
Cattle dung and pollution
While government cleanliness programmes focus on open defecation and the need for toilets, cattle dung, which is arguably the biggest reason for insanitation in rural India, remains neglected. The heaps of dung dumped near the cattle sheds and in open spaces ultimately contaminate surface and groundwater. A study of groundwater samples done by Greenpeace in Punjab found that wells located within the villages had high nitrate pollution probably coming from concentration of human sewage and cattle.
On the other hand, lack of application of organic manure reduces carbon content of the soil which influences soil structure, water retention, microbial activities, soil aeration and nutrient retention. Organic manure also encourages growth of useful microorganisms enabling better absorption of nutrients from chemical fertilisers.
Dealing with cattle dung
There have been two approaches to deal with cattle dung. One is to make compost through compost pits and use it in fields and another is using it for production of biogas.
The Union Ministry of New and Renewable Energy has been promoting biogas plants through the National Project on Biogas Development since 1981-82. It was renamed National Biogas and Manure Management Programme (NBMMP) in 2002-03 for implementation during the Tenth Plan.
Till December 2015, 4.86 million biogas plants had been set up under the scheme with Maharashtra topping the charts followed by Andhra Pradesh and Karnataka for maximum plants.
In 2014-15, the estimated biogas production was 20757.29 cubic metres.
Besides being cleaner energy source than fuelwood and dung cakes, biogas is also cheaper and more readily available than LPG. Another big advantage is the enriched slurry, which can be directly applied to the fields. The digested slurry contains 80 percent carbon, 1.8 percent nitrogen, 1 percent phosphorous and 0.9 percent potash making it an excellent source of not only humus but also micronutrients for crops. Also, it takes lesser time to produce as compared to a compost pit.
“A biogas plant will produce this slurry in 52 days whereas when you try to prepare a compost from the same manure, it will take 90 days,” says Ujjawal Dagar, who has been using biogas at his farm in Sonepat district of Haryana.
Problems with maintenance
While the installation of biogas plants has seen a steady decline (from 1,15,377 in 2012-13 to 84,882 in 2014-15), it’s the functioning of already installed plants that remains an issue.
An evaluation study done in 62 districts by the Planning Commission found that only 45 percent of the biogas plants were fully functional. On the other hand, a CAG report found the failure report to be 26 percent with much variance between states. While Gujarat had a failure rate of 6 percent at most, Jharkhand had a failure rate of 74 percent.
The main reasons for plants becoming non-functional were structural and operational problems, non-availability of dung, easy availability of other convenient fuels, choking of the inlet or the outlet, corrosion or leakage in the pipeline, scum formation in the digester and water accumulation in the gas pipe. Even though some of these problems could have been rectified by the beneficiaries themselves, they were not properly trained about preventive maintenance.
“The inferior construction is the biggest reason for failures. There is a huge gap between the design approved by government agencies and what is constructed on site. Many a times, beneficiaries also try to save the cost of construction by allowing the mason to do inferior job resulting in premature failure,” says Amit Nalawade, who is supplying portable biogas plants in Kolhapur district of Maharashtra.
Another issue is inconsistent feeding. Under or over feeding of dung can harm the efficiency of a plant. “A farmer with 10-12 livestock may pour all of the dung in the plant hoping that this will produce more gas. However, feeding capacity of a bio-gas plant is limited. Such abuse will ultimately lead to failure and hence better systematic training of beneficiaries is required,” Nalawade says.
A study done in Uttar Pradesh found that the average operational life of a plant was around four years due to lack of maintenance. Lack of proper staff at district levels often lead to inadequate supervision during construction as also physical verification of plants at different levels.
But there’s still hope
The educated and the resourceful, however, are finding biogas to be a useful alternative. “Since the time I installed the biogas plant, I haven’t used my LPG connection. The only problem I have faced is of moisture accumulation but it’s easy to deal with it. You just need to take the supply line to a height of around 100 feet and make sure there’s no bend in the pipe. This will force the moisture to flow back into the digester due to gravity,” says Kamaljeet Hayer of Sohangarh Rattewal village of Ferozepur district in Punjab.
Civil society organisations are also pushing for biogas. Foundation for Ecological Security (FES) has been working in tribal areas of south Rajasthan to reduce dependence on forest and emission of greenhouse gases through use of cow dung as cooking fuel.
“We have several biogas plants in our field area, some working for as long as 10 years, without any problem. Quality of construction and interest of the beneficiary family are the main criteria for any plant to work well. We ensure good quality through supervision during construction phase,” says Shantanu Sinha Roy of FES.
Improvement is seen in forest cover around the villages where biogas plants have been set up as people stop felling trees to get fuelwood. “There are tremendous benefits of biogas. Besides a healthier option for women and children, it also promotes livestock economy because the family can’t easily shun cattle which are directly linked to the kitchen and the farm. The fact that people have total control over this fuel makes it the most sustainable and accessible option,” Roy says.
Progress in efficient use of cattle dung can pave the way for use of human excreta in cooking as well. Currently most of the toilet waste flows into the ponds and rivers or seeps into the ground. While government encourages connection of sanitary toilets to biogas plants, there are not many takers for the proposal probably due to social and psychological barriers. Still, around 60,607 biogas plants in 11 states were linked to sanitary toilets till December 2015.
A time will come when we won’t have an issue using the night soil for cooking food and using the slurry in the garden. Considering the money we can save on LPG and sewage treatment, there can’t be a better model for tomorrow.