I'm Steve Ember with the VOA Special English Agriculture Report.

Farmers usually have to destroy all of their chickens and other birds if a case of bird flu is found. Then they face another difficult decision: What to do with the remains?

Some farmers choose composting. They avoid the danger of transporting infected birds, the cost of burning them and the risk that burial could pollute ground water.

Composting uses the natural action of microorganisms to break down organic materials. Many agricultural extension services explain ways to compost animal remains.

Composting must be carefully controlled. The balance of carbon and nitrogen is very important. A correct nutrient balance requires extra material like dry grass or pieces of wood. These materials are called bulking agents.

Also, the compost must hold the right amount of water. Too little, and bacteria cannot do their job; too much, and air will not reach all the compost. The mixture should reach temperatures between fifty-seven and about sixty-three degrees Celsius.

If the pile begins to smell bad, this could be a sign that ammonia is building up. Adding the chemical ferrous sulfate can help solve this problem.

Experts say a simple way to compost farm birds is to create a windrow. A windrow is simply a mass of material. It should be three to four meters wide and about two meters high. It can be as long as space permits.

A windrow this size should contain three levels of birds, placed between layers of bulking agent.

Windrows should not be near homes, animal shelters or water resources.

Experts say one thousand birds weighing a little over one kilogram each would need about ten cubic meters of bulking material. The material should be placed loosely so air can pass through it.

The windrow should take about one week to reach a high temperature. After another week to ten days, the temperature will begin to drop. At this point, the windrow must be turned.

Turn all the material completely. If it is too dry, add water. If it is too wet, add more bulking agent. Completely bury any bird remains that might be uncovered.

Experts say that after about three to four weeks more, the compost should be ready to use as fertilizer.

This VOA Special English Agriculture Report was written by Mario Ritter. Read and hear our reports at voaspecialenglish.com. We also have a link to detailed information from the University of Maryland on composting poultry. I'm Steve Ember.