Kazi Farms prefers composting over biogas for productive use of poultry litter
Large egg farms in Bangladesh have a problem: they produce a lot of smelly manure. Farmers buy manure during a certain season; the rest of the year it piles up, and provokes complaints of odour and flies from neighbouring households. Some large farms have found that the best way to manage this problem is to convert the manure into organic fertilizer.
Kazi Farms Group is one of the largest poultry producers in the country. Considering the increasing demand for organic fertilizer, and the need for better management of poultry manure, they have moved to produce organic fertilizer from poultry manure.
Bangladesh is an agriculture-based country, with 80% of its population earning their bread from the sector. These people tend to use cheap chemical fertilisers. Continuous use of chemical fertilizer reduces the fertility of the land, according to Shah Mohammad Arefin,AGM, Kazi Organic Fertilizer Ltd(Kazi Farms Ltd) told the Dhaka Tribune.
Organic fertilizer is becoming popular because crop farmers spend a lot of money to irrigate their fields. Organic fertilizers contain organic matter which holds water like a sponge, and reduces the need for irrigation. Many consumers are concerned about chemicals in their food, and prefer to buy vegetables grown with organic fertilizers.
Taking the matter into account, Kazi Farms Group is producing organic fertilizer by composting poultry manure. These fertilizers have already become popular among farmers.
However, government policy in Bangladesh requires all large poultry farms to set up biogas plants in order to produce biogas from poultry manure. This policy has not been very successful.
Erecting large biogas plants is not possible for most poultry farms because these plants require a lot of land and require a huge investment to build. An egg farm with 10,000 hens produces at least one tonne of manure every day. To feed one tonne of manure into a biogas plant, it must first be mixed with one tonne of water. When two tonnes of manure+water are fed into the plant, two tonnes of digested slurry (liquid waste) come out.
The fertilizer regulations do not permit selling biogas slurry as liquid fertiliser. So the digested slurry from a biogas plant cannot be sold as organic fertiliser without putting it through an expensive drying process.
In the past, Kazi Farms set up many large biogas plants, but found that when they started operating these biogas plants, they were producing a huge volume of slurry. They were storing the slurry in ponds on their property, but after some time the ponds were full, and they had to stop operating the biogas plants because they had no space to store any more slurry. During the rainy season the ponds would overflow into their neighbour’s fields, leading to complaints and demands for compensation in some cases. Kazi Farms found that biogas plants do not solve the waste (manure) disposal problem, but simply as transform problematic waste (solid poultry manure) into another (liquid slurry which cannot be sold).
In comparison, a compost plant is far less expensive to build than a biogas plant (which processes the same volume of manure); the compost plant also requires far less land as it does not produce any liquid waste, and therefore does not need a pond to store liquid waste.
Composting is a far more appropriate solution to the problem of poultry manure management. Compost has no odour and can easily be sold. Once compost has been tested by the relevant authorities, it can be bagged and sold as branded organic fertilizer.
Kazi Farms Group has five large egg farms, which produce a total of one million eggs every day. These also produce a total of about 170 tonnes of manure every day. As of now, Kazi Farms runs six compost plants and produces 65 tonnes of organic fertilizer every day. The group also runs three large bio-gas plants, but it has concluded that building these plants was a mistake.
The government wants all poultry farms to produce biogas from poultry manure, and most the large farms in Bangladesh have attempted to build large biogas plants, only to find it that they could not operate the plants. Large biogas plants produce a large volume of slurry, and as land is so expensive, most farms simply do not have enough land for a huge slurry pond. The engineers who build large biogas plants in Bangladesh do not have enough experience, and have no idea how much space is required to store and treat the liquid waste of a large biogas plant. To produce one cubic meter gas requires 20 kg mixture of manure and water, and will produce 20kg of liquid slurry. There is a cost involved; the biogas plant and the ETP required to treat the slurry both require a huge investment to build; that means a large monthly bank interest cost. The plant and ETP also require skilled maintenance and labour to operate. At the end of the day, the value of the gas produced is less than all these costs.
On the other hand, using the manure to produce compost or organic fertilizer is more economical as the composting converts smelly manure into an odourless product which can easily be sold.
Though, the government is considering allowing the sale of liquid fertilizers, it will be difficult to ensure the quality, as it is possible that dishonest traders might try to package sewage and sell it as liquid fertilizer, said Arefin.
Last year, Kazi Farms has received an organic fertilizer license and started commercial marketing of organic fertilizers. This has solved the chicken manure management problem, said Arefin. If the government were to encourage composting to manage poultry manure and poultry litter, the waste management problem of the poultry sector will be solved, he added.
“Ammonia gas, which is produced by litter, is harmful for chickens as well as the inhabitants living in the area. So considering the environmental and health issues, we are giving importance on making compost from poultry manure for better and quick waste management,” Dr AKM Ataur RAhman, Livestock Economist of Department of Livestock (DLS) told the Dhaka Tribune. The production of biogas from poultry manure produces waste, which needs further treatment. But producing compost solves the waste management problem, he added.
On the other hand, composting poultry manure means the country’s farmers will get quality organic fertilizers at a reasonable prices, produced under supervision of experts using latest technology.
“Making compost or organic fertilisers is a more efficient system of waste management than producing biogas. Biogas production takes more time and needs more resources, and at the end of the biogas process you still have waste which is discharged from the biogas plant,” said sector people. As the fertilizer regulations do not permit sale of liquid fertilizer, the biogas slurry cannot be sold, they added. Sector people also urged the policy makers to consider the use of manure in compost production to ensure better management of poultry waste.
What the experts say
“Making compost from the poultry litter is a good initiative as it has two benefits, better management of waste as well as meeting the demand for organic fertilizers. It is environment friendly and cost effective,” Professor Dr. Md. Jahangir Alam, Dean, Faculty of Animal Science and Veterinary Medicine, Sher-e-Bangla Agriculture University, told the Dhaka Tribune. A long term benefit of compost is that it keeps the land fertile, and can restore the fertility of land which has deteriorated due to the use of chemical fertilizers, said Dr Jahangir. On the other hand, it provides balanced and natural nutrients to crops, he said.