There are a number of ways to judge decomposition, the most direct of which would likely be to measure CO2 offput in an aerobic environment. This directly reflects the amount of organisms metabolically active in the material. Unfortunately, any large amount of dung is bound to have anaerobic portions, that this method may fall short for.
You can also measure the solubilization of the material, which will reflect enzymatic action (literal breakdown) of the material. Use of a sterile control is necessary to judge the initial amount of soluble material.
There are also tests to reveal the changes in available nitrogen and carbon in the material, which will get fixed into organisms as time goes on and it's broken down microbially. These tests can also reveal the change over time of abiotic factors in the quality of the dung for mushroom growing.
Dear Sidnee Ober-Singleton thanks for your response! I am exactly try to test how long dung is suitable in environments to fungal colonization, so I am supposing that litterbags could be a good option to me, just because I'll be able to let the bags in field and check it to count time to dung decomposition. I will execute the chemical steps in another moment, but I really appreciate your sugestion to tests to reveal the changes in available nitrogen and carbon in the material and I gonna do it.
Hi Francisco. Not really clear about your question, as the true coprophils are already in the dung when it is excreted - they require a passage through the herbivore gut to stimulate spore germination. If dung is dry when collected it can be kept in paper bags for months, even years, and will produce the normal growth of fungi when rehydrated and incubated. Coprophilous fungi alone are not responsible for decomposition - they will be interacting with the bacteria and fauna in the dung. I suppose you could do something along the lines of Webster and his students, e.g sterilise dung and then inoculate with different species, alone and in combination, and record the decomposition rate by weighing at intervals.