How to Assess the Moisture of Sawdust and Other Litter?
Sawdust is a key component in fermentation bed systems for pigs due to its fine texture, high cellulose and hemicellulose content, excellent water absorption, good ventilation properties, and resistance to carbonization and decomposition. These characteristics make it an ideal litter material that supports microbial activity. When the moisture level reaches around 65% (as per the Goldpox fermentation bed standard), the beneficial bacteria can function optimally, initiating the fermentation process.
A simple way to check the moisture is by grabbing a handful of the material. If it forms a loose clump but doesn’t drip water when squeezed, it’s likely at the right moisture level. If it's too wet or too dry, it may hinder microbial activity and affect the overall performance of the system.
But how do you accurately assess the moisture content of sawdust and other litter in practice? Here's a practical guide based on the structure of the Goldfish fermentation bed:
a. **Moisture in the sawdust itself**: The water content varies depending on the type and source of the sawdust. Fresh sawdust from trees like fir, camphor, or mixed wood typically has a moisture content of around 60%. On the other hand, older, dried sawdust may have as low as 30% moisture. This should be considered when calculating the initial mix.
For example, a Goldfish fermentation bed covering 20 square meters with 50 cm thick sawdust would require about 1900 kg of sawdust. If the dry sawdust has 30% moisture, that equates to approximately 570 kg of water.
b. **Water from pig excrement**: Pig waste contributes significantly to the moisture in the system. Feces generally contain about 60% water, which is usually not a major concern. However, urine is a much larger source of moisture. On average, each pig produces about 4 kg of urine daily. For a 20-square-meter bed housing 15–20 pigs, this could add up to around 60 kg of water per day—making it a primary source of moisture that doesn't need additional watering.
c. **Other water sources**: Water from drinking troughs, feed residues, or rain leakage can also contribute. It's important to manage these to prevent excess moisture. While they are relatively minor, proper sheltering and drainage are essential to avoid over-saturation.
After some time, the moisture level will naturally stabilize during the fermentation process, allowing the microbes to become active and perform at their best. However, if the bed becomes too wet, immediate action is needed—such as aerating from the bottom, removing overly dry material, drying it out, or adding more dry sawdust.
Additionally, fresh sawdust should not be sprayed directly, as it already contains enough moisture. Only a small amount (about 5–10 cm deep) should be misted on old sawdust. In northern regions, where the air is drier, light spraying on the surface may be necessary. In humid areas, it’s better to avoid spraying altogether, unless the bed becomes excessively dry. Always monitor the environment and adjust accordingly to maintain optimal conditions for microbial activity.
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