Object  Changes on soluble carbon and nitrogen in cow bed material during composting with the aid of various exogenous bacterial fermentation agents were studied.

  Method   Contents of soluble nitrogen, i.e., ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N), soluble organic nitrogen (SON), and soluble carbon, i.e., soluble total carbon (STC) and soluble organic carbon (SOC) in the cow bed material, which had been used at a cattle ranch for 3 years, that was added with different commercially available bacteria agents were measured during the fermentation to determine the optimal application of the agents.

  Results   The addition of fermentation agents increased NH₄⁺-N, SON, and SOC, but reduced NO₃⁻-N. Among the 3 agents tested, Guolong Biological Bed Inoculants performed best on most evaluation criteria, and it was followed by Baifeng Livestock and Poultry Bao and Feng Li Jing. No consistent display in SOC by the agents was observed. NH₄⁺-N and STC increased to peak in 20 d and declined afterward. NO₃⁻-N and SON tended to increase continuously to reach a maximum in 50 d. The SOC content toped in 10 d and then on a decreasing trend as the fermentation progressed.

  Conclusion   The application of bacteria agents could increase the available carbon and nitrogen in the compost. However, there was the risk of increasing ammonia volatilization. Hence, an agent specific for the fermentation of livestock and poultry excrement would be recommended to be added to the compost for the fermentation of cow bed material.