ENVIRONMENTAL FACTORS AFFECTING DECOMPOSITION:

           There are three environmental factors affecting the interwoven chemical and microbial breakdown of the organic matter.

1. Oxygen:

Composting can be defined in the terms of availability of oxygen. Aerobic decomposition means  that the active microbes in the heap require  oxygen,  while in anaerobic decomposition, the active microbes do not require oxygen to live and grow. Temperature, moisture content, the size of bacterial populations, and availability of nutrients limit and determine how much oxygen your heap uses.

2. Moisture:

The amount of moisture in your heap should be as high as possible, while still allowing air to filter into the pore spaces for the benefit of aerobic bacteria. Individual bacterial hold various percentages of moisture in compost and determine the  amount of water that can be added. For example, woody and fibrous material, such as bark, sawdust,  wood chips, hay and straw have the capacity to hold up to 75 to 85 percent of moisture. " Green manure", such as lawn clipping and vegetable trimming are able to hold 50 to 60 percent moisture.

The minimum moisture content at which bacterial activity takes place is from 12 to 15 percent. Obviously, the closer the moisture content of a composting mass approaches these low levels, the slower will be the compost process. As a rule of thumb, the moisture content becomes a limited factor when it drops below 45 or 50 percent.

3. Temperature:

Temperature is an important factor in the biological of a compost heap. Low outside temperatures  during the winter months slow the decomposition process, while warmer temperatures speed it up. During the warmer months of the year, intense microbial activity inside the heap caused composting to proceed at extremely high temperatures. The microbes which decomposes the raw materials fall into basically two categories : mesospheric, those that live and grow in temperatures of 50 °F to 113 °F (10 °C to 45 °C), and thermophillic those that thrive in temperatures of 113 °F to 158 °F (45 °C to 70 °C). The initial heat heap phase that most garden compost goes through is thermophillic. The organic material dehydrated very quickly in this phase and should be kept aerated and moistened. The high temperatures are beneficial to the gardener because they kill weed seeds and germs that could be detrimental to vegetation. The next holds at 100 °F for a while and different microbes predominate. Then finally, the ambient phase where the pleasant earthly odor originates and material has produced compost.