Manure can be prepared in fields primarily through direct application from livestock or by composting near or on the field before spreading.
While the provided reference lists sources of manure, it doesn't directly detail how manure is prepared in the fields themselves. Therefore, this response will focus on common methods of manure preparation relating directly to field application.
Here are the primary ways manure is prepared for use in fields:
1. Direct Application from Grazing Animals
- Method: Livestock (cattle, sheep, goats, etc.) are allowed to graze directly on the fields. As they graze, they deposit manure (dung and urine) directly onto the soil.
- Preparation Aspect: This is the most basic form. No actual preparation of the manure occurs beforehand, but the animals distribute it naturally. This is considered a preparation method because the application happens concurrent with manure production.
- Considerations:
- Requires careful management to prevent overgrazing and soil compaction.
- Uneven distribution of manure can occur if animals congregate in certain areas.
- Nutrient content and availability depend on the animals' diet and digestion processes.
- Requires managing stocking rates to avoid nutrient overloading or under-application.
2. Field Composting
- Method: Manure (often mixed with bedding, crop residues, or other organic matter) is piled in windrows or heaps directly in or adjacent to the field where it will be applied. These piles are turned periodically to aerate the material, promoting decomposition.
- Preparation Aspect: Composting transforms raw manure into a more stable, nutrient-rich product. It reduces odors, kills pathogens, and improves handling characteristics.
- Considerations:
- Requires space in or near the field.
- Turning equipment is needed (tractor with a loader, compost turner).
- Composting process needs to be managed (moisture content, aeration) to ensure proper decomposition.
- Finished compost is then spread onto the field.
3. Solid Manure Spreading
- Method: Solid manure (often from cattle sheds or poultry houses) is collected, stored, and then spread onto the field using a manure spreader.
- Preparation Aspect: Before spreading, some preparation might involve simply letting the manure partially decompose in a pile. This reduces odors and allows for easier spreading. Mixing different types of manure (e.g., poultry litter with cattle manure) before spreading can also be a form of preparation.
- Considerations:
- Requires a manure spreader and a tractor.
- Even distribution is key.
- Timing of application is crucial to minimize nutrient losses.
4. Liquid Manure Application
- Method: Liquid manure (slurry from biogas plants, cattle manure mixed with water, etc.) is stored in tanks or lagoons and then applied to the field using specialized equipment, such as tankers with injectors or irrigation systems.
- Preparation Aspect: Preparation might include agitating the slurry to ensure a homogeneous mixture before spreading and, in some cases, diluting the manure with water to reduce nutrient concentration and improve application uniformity. Anaerobic digestion in biogas plants, as the reference mentioned, also prepares the manure by stabilizing it and reducing odor.
- Considerations:
- Requires specialized equipment for storage and application.
- Risk of nutrient runoff and odor problems if not managed properly.
- Application rates must be carefully controlled.
- Injection techniques minimize ammonia volatilization and odor.
In summary, preparing manure in fields can involve direct deposition by grazing animals, composting in windrows or piles, or spreading solid or liquid manure after some initial storage and potentially mixing or dilution. The specific method depends on the type of manure, available equipment, and field conditions.
