To maintain aerobic biological activity, the moisture content of the compost mass should be about

ANS:C - 55%

Maintaining an adequate moisture content in composting is crucial for the success of the process. While the optimal moisture content can vary depending on factors such as the composition of materials, environmental conditions, and the composting method used, a moisture content of around 55% is often considered suitable for aerobic biological activity in compost. Here's why a moisture content of approximately 55% is beneficial for composting:

1. Microbial Activity: Microorganisms, including bacteria, fungi, and other decomposers, are essential for breaking down organic matter in compost. These microorganisms require water to carry out metabolic processes involved in decomposition. Adequate moisture content ensures that microbial activity is not inhibited due to water stress, allowing them to thrive and efficiently break down organic materials.
2. Oxygen Diffusion: In aerobic composting, oxygen is required for the respiration of aerobic microorganisms, which decompose organic matter while releasing heat and carbon dioxide. Maintaining an optimal moisture content facilitates the diffusion of oxygen throughout the composting mass. Excessively dry conditions can limit oxygen availability, slowing down microbial activity, while overly wet conditions can restrict oxygen diffusion, leading to anaerobic conditions and the production of foul-smelling compounds.
3. Temperature Regulation: Water plays a crucial role in regulating the temperature of the composting pile. Moisture helps to distribute heat evenly throughout the pile, promoting uniform decomposition and preventing hot spots or areas of excessive heating. Additionally, moisture acts as a thermal buffer, helping to moderate temperature fluctuations caused by environmental factors such as sunlight and ambient temperature.
4. Nutrient Availability: Moisture facilitates the dissolution and transport of nutrients within the composting pile. This allows microorganisms to access essential nutrients necessary for their growth and metabolic activities. Maintaining an optimal moisture content ensures that nutrients are readily available to support microbial activity and the decomposition of organic materials.
5. Texture and Structure: Adequate moisture content helps to maintain the structural integrity and texture of the composting materials. It promotes cohesion and aggregation of particles, facilitating the formation of a stable compost pile. Proper moisture content also prevents excessive compaction or waterlogging, which can impede airflow and drainage within the composting pile.

Overall, a moisture content of around 55% provides a balance between ensuring sufficient water availability for microbial activity and preventing waterlogged conditions that can hinder oxygen diffusion and promote anaerobic decomposition. However, it's essential to monitor and adjust moisture levels as needed throughout the composting process to optimize decomposition and produce high-quality compost.