湿度对堆肥理化性质的影响

水分是堆肥微生物生命活动的基础 ,也是堆肥中重要的工艺控制参数。弄清湿度对堆肥微生物及理化性质的影响 ,对于优化堆肥工艺参数、提高堆肥效率、降低投资和运行成本具有重要意义。综述了堆肥湿度研究的动态 ,指出了当前研究中存在的问题 ,并提出了未来的研究方向。大量的研究表明 ,湿度低于 4 5 %或高于 6 5 %都不利于堆肥处理。湿度太高会导致堆料的压实度增加、FAS减少、透气性能降低 ,从而导致堆体内氧气供应不足、堆肥升温困难、有机物降解速率降低、堆肥周期延长。湿度过低 ,水分会限制堆肥微生物的新陈代谢 ,导致微生物活性下降、堆肥腐熟困难。由于鼓风、散热、水蒸发等会使堆体内存在湿度的空间变异 ,也会降低堆肥效率和堆肥产品的质量。另外 ,堆肥湿度还影响堆肥的保肥能力。由各文献得出结论 ,堆肥的最佳湿度范围一般为 5 0 %～ 6 0 %左右

Effects of moisture content of compost on its physical and chemical properties

Water, an important processing parameter, is essential to the activity of microorganisms in composting. To understand the effect of composting on physical and chemical properties is of great important to optimize composting parameters, improve its efficiency and reduce capital investment and operational costs. The researches of moisture content in composts are summarized to find out the main existed problems and to suggest its development in the future. The Previous studies indicated that it was not in favor of composting when the moisture content was below 45% or above 65%. If the moisture content in composting is too high, the increase of compaction and the reduction of free air space and bad air permeability in compost pile cause insufficient oxygen supply for microorganisms, resulting in less increase in temperature of composting; therefore, decomposition rate of organic matters decrease and the period of composting will be prolonged. If the moisture of composting is too low, the metabolism of microorganisms will be limited which may lead to inhibit the microbial activity and the mature of composts; therefore, both of the efficiency of composting and the quality of composts are reduced. The existence of spatial variation of moisture content in compost pile, due to aeration, heat dissipation and water evaporation, can also result in the decrease in the composting efficiency and the quality of compost. In addition, retention capability of fertilizer is influenced by the compost moisture, too. It is concluded that the optimal moisture content for composting usually ranges from 50% to 60%.