As illustrated in Chapter 2, most industrial production livestock production in the study countries is concentrated in and around major cities or areas otherwise favored by infrastructure. This concentration often leads to massive nutrient (nitrogen, phosphate and potassium) surpluses in these areas, causing pollution and eutrophication of surface and ground water. The emission of greenhouse (methane, nitrous oxide) and other gases (ammonia) are other important forms of pollution. Nutrient loads in regions around cities in terms of both nitrogen and phosphorous are illustrated for Asia in Figure 7.1.
Disposal practices for manure and dead animals directly impact on nutrient balances, and also vary across scales of operation. Traditionally, by-products of livestock production in the four countries have been disposed of by: 1) applying it to land to improve the physical properties of the soil for plants, 2) using it as an animal feed (other animals, fish feed, oyster farming), 3) using it to create energy (directly burning for heat or creation of methane gas), 4) using it as a cement lining for floors, 6) dumped into rivers, 7) burial, 8) incineration and 9) brick making.
Swine production is probably the least environmental friendly livestock production. As a result, countries such as Thailand, the Philippines and Brazil have set regulations to control sewage from these operations. In Brazil and Thailand they are also providing funds to aid farmers in protecting the environment. For poultry, industrialization is less obviously an environmental problem. This is assisted by the fact that in all the study countries chicken manure is salable. Therefore, the increased volumes of manure produced by the large farms have not created the same absorption problem as in swine production.
Figure 7.1a Estimated nutrient balances for nitrogen stemming from livestock production in Asia in 2002 (kg N/ha)
Source: P. Gerber, Livestock Environment and Development Secretariat, LEAD, FAO.
In Thailand, manure coming from poultry farms goes into a holding pond, cesspool, a biodigester, or is dried. It may then either be sold to a middleman, used on a farm as a fertilizer or as fish food. Dead animals will be used either on farm or sold to a secondary market for with food or human consumption.
Figure 7.1b Estimated nutrient balances for phosphorous (kg P2O5/ha) stemming from livestock production in Asia in 2002
Source: P. Gerber, Livestock Environment and Development Secretariat, LEAD, FAO.
In India, broiler manure tends to be removed either by family or hired labor. It is then either piled in an open or closed shed, or immediately used. If it is used on farm, it is primarily for organic fertilizer. If it is not used on farm, most likely it would be sold for organic fertilizer, brick making, fuel, mushroom substrate, or possibly it is dumped. Similar practices exist in other study countries, but usually broiler manure in these countries is valued as fertilizer.
In Brazil, the disposal patterns of layer manure is either used on farm or sold to manure trades. Dead animals are put into a cesspool, composted, or buried. In the Philippines, manure once cleaned out of the houses may go into and open pit, laid on the ground, or into an open pit. After that it would either be used on farm or sold to the market. Dead piglets tend to be buried. Other countries may have lagoons for their manure, biodigesters, or feed it to fish.
Under these disposal practices, the value of manure can vary from a net loss when the material is hauled away and destroyed to a valuable joint product when it is sold for use on fruits and vegetables. Various entrepreneurs have developed ways to add value and improve manure utilization, such as marketing it as an enhanced fertilizer, an animal feed, or for fuel. The success of the marketing options depends on the types of crops utilizing the manure, the distance from the farm that needs it, and the willingness of the individual to use the manure as a product.
The potential buyers of manure are other farmers (fruit, vegetable, field crops, organic), commercial nurseries, home and garden centers, greenhouses, and even homeowners. In most cases, the market for manure is very local because of the cost of transportation. Undesirable characteristics associated with raw manure are its being too wet; lacking uniformity; containing too many feathers; possibly containing toxic chemicals; often being lumpy; containing weed seeds; giving unpredictable response; often being the wrong nutrient balance; not always being available when needed; providing good breeding ground for flies; possibly burning the crops; and being smelly.
Because ruminants are able to use the non-protein nitrogen in poultry and swine wastes, it can also be used as a supplement feed for certain animals. Furthermore, both Thailand and India reported the use of some manures as fish feed. The acceptability of the use of manure and dead animals as feed additives is dwindling worldwide because of concern about BSE. Although Brazil previously used meat and bone meal as feed additives, they have stopped doing this since both the EU and the U.S. have banned imports from countries permitting ruminant-to-ruminant feed practices. Even use in feeds for non-ruminants has ceased because of the danger of de-certification as an exporter.
Methane produced through anaerobic digestion is another potential market for manure. It can be derived directly through a biological process such as combustion, or indirectly through generation of biogas, which is a mixture of methane and carbon dioxide. Most methane produced has been burned for heat or used as a fuel for internal combustion engines. The equipment used for producing methane is not simple and it is fairly expensive, posing a problem for the economic feasibility of biogas production. The major factors in the high costs of these methane-producing structures are: the high cost of properly designed structures, mixing equipment, and gas-control devices; the precautions to avoid explosions; and the need to store methane and the digested liquid manure.
The generation of biogas has multiple benefits beside the generation of a combustible fuel. For instance, by-products from sludge of a digester that uses manure can be used as a feed supplement while the liquid effluent can support fish growth and make aquaculture possible. The economic feasibility of methane production is increased when the utilization options of the residues are also taken into account. The problem with this is that after methane has been generated, one still has to get rid of the excess nitrogen and phosphorous.
Because of the expense of biogas generation, Thailand has started programs that provide partial funding for construction the waste treatment system such as biogas digester and multi-level pond. The amount provided by the governmental funds for installing of waste water treatment system range from 20,000 to more than 150,000 baht per farm, approximately 40-60 percent of the total installation cost.[31] In this program, the government will subsidize up to 38 percent of the construction cost and low cost loan as well as loan facilitation will be sought to assist the farm owners.
Farms with insufficient land for spreading manure or facilities for otherwise reducing it, can still improve mass nutrient balances through sales of manure to others. Presumably there is a market for manure only because of its value as a fertilizer or fuel, so manure sales and transport off the farm are generally good signs for management of mass balances.
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[31] Approximately 42 baht
equaled US$1 at the time of writing in mid-2003. |
