Management of Manure

Manure should be removed from animal shelters to prevent the build-up of diseases and parasites. If collected and applied to crops in a rational manner, it is a valuable resource, replacing some, or all of the purchased fertilizer that must be used to obtain high crop yields.

Background Methods Poultry Guinea Pigs and Rabbits Sheep and Goats Pigs Cattle References and Further Reading   See also Economic Value of Manure

Where animals are allowed to roam freely, they deposit urine and faeces more-or-less at random, over the whole of their ranging area, where it serves as a source of nutrients for the plants growing nearby. While it helps to maintain soil fertility on the farm, it cannot easily be collected for rational use on planted crops. When animals are kept in confinement, however, the manure must be removed from the enclosures, to prevent the build-up of diseases and parasites. While this can be a relatively time-consuming job, it offers the opportunity to collect much of the manure, which might otherwise be wasted. If this is then used in a directed manner, applied specifically to the most important crops on the farm, it becomes a valuable resource, since it will reduce the need to buy expensive fertilizer products on the open market.

The handling of manure will depend on the design of the shelters and the animal species kept in them. In general terms, although it will add to the cost of the pens, a solid floor of cement or of crushed rock will allow the manure to be swept up with a minimum of effort and contamination with soil. When used as fertilizer, manure is best dug into the soil. If applied to the soil surface, a considerable amount of the nitrogen in the manure will be lost to the atmosphere as it dries. This can be avoided if the material is dug into the soil, close to the root zone of the target plants. The richest material should be applied to the plants of highest value on the farm, such as coffee trees, vegetables or ornamentals to be sold as cut flowers.

Chicken manure will tend to collect underneath the perches and it should be removed at frequent intervals. The digestive system of chickens is less efficient than ruminants and many nutrients are voided in the faeces that can be utilized by other species of livestock. If collected and thoroughly dried, poultry droppings can be mixed with energy-based feeds such as rice polishings or chopped cereal straw, where they will act as a valuable source of dietary nitrogen when fed to ruminant livestock. Alternatively, the droppings will serve as a rich fertilizer.

If kept in a raised cage with a wire, or slatted wooden floor, most of the dung pellets will fall through onto the ground below, where they can be easily swept up. This should be done periodically, to prevent annoying insects from using them to incubate their eggs. The pellets make a useful fertilizer, but unless there are many animals, the amounts produced will be insufficient for application to more than a section of the home vegetable garden.

When fed on a high-roughage diet, rabbits as well as some rodents are known to eat some of their own soft faecal pellets, in a process known as caecotrophy. This is a mechanism to increase the digestibility of the feed by passing it twice through the digestive system. If all of the faecal material is immediately removed from their cages, they will not be able to re-consume their soft droppings. It will then be necessary to feed these animals on a good quality diet with high digestibility, to ensure that they can meet their nutritional requirements.

Small ruminants normally produce pelleted faeces which are already reasonably dry and easily handled. As with poultry droppings, the pellets can be dug into the soil near to valuable crops, where they will act as a good, well-balanced fertilizer.

Pigs produce large amounts of relatively moist faeces. Pigs also commonly harbour internal parasites that can infect humans, so the dung requires careful handling to avoid infection. The best way to destroy the eggs of intestinal worms is to compost the material. A pit is dug, into which the manure is placed. A quantity of high-fibre material such as straw, roughage rejected by the animals, or maize stover, can be added and mixed with the manure, together with enough water to form a thick slurry. The pit is then covered to prevent the entry of annoying insects and the emergence of unpleasant smells. As the manure starts to compost, the temperature will rise sharply and this will be sufficient to kill the parasite eggs and any immature worms that hatch from them. More manure and roughage can be added on top as it is collected and occasionally, the material in the pit should be turned over with a fork. After a period of a few weeks (the process will be faster in hot weather), the smell from the pit will disappear and the material will take on a friable, solid consistency. It can then be dug out of the pit for application to crops.

Cattle manure has a fluid consistency and is produced in relatively large quantities. Although it presents less danger of infection to humans, it can be best handled as described above for pig manure. In the Highlands of Kenya where almost all farms keep one or two dairy cows, the animals are considered to be the axis about which the farm revolves, since without the manure from the animals, yields of the main cash (coffee from 1,500-1,800 metres above sea level and tea above that level) and subsistence crops (vegetables, maize, cassava and potatoes) would be so reduced that small-scale farming would not be economically viable.

For more on Manure management see the IFOAM publication by Eyhorn et al.

The value of organic manures

Organic manures include all nutrient sources derived from plant or animal origin. Unfortunately they are often an underestimated source of nutrients.

Organic manures are very different from chemical or mineral fertilizers. The basic difference is that they contain organic matter. Due to their organic matter content they are a slow source of nutrients and supply several nutrients at once. However, they mainly improve the quality of the soil.

Lekasi, J.K., Tanner, J.C., Kimani, S.K. and Harris, P.J.C. (2001). Managing Manure to Sustain Smallholder Livelihoods in the East African Highlands. DFID - Natural Resources Systems Programme. HDRA, Coventry, United Kingdom