Source: Alberta Agriculture and Forestry
‘There are several management considerations to make when deciding where and how to best utilize available manure and compost resources,’ says Trevor Wallace, nutrient management specialist with Alberta Agriculture and Forestry.
Considering the right nutrient source (one of the 4Rs of nutrient stewardship) to use in a specific situation will optimize manure or compost use efficiency.
‘If your farm only produces one type of manure, you don’t have the option of selecting different sources for different situations, but you can target the manure source you have to a situation that provides the greatest return from that manure. If you have access to multiple types of manure and compost, you have the opportunity to target the various sources to get the greatest benefit. To decide where best to utilize available sources of manure or compost, you need to know the nutrient contents and characteristics of the various manures or composts, the soil characteristics of the different fields, and planned crop requirements.’
Manure nutrient composition varies widely due to factors such as different animal species, bedding and feeding practices, types of manure (solid or liquid), methods of handling, and storage (i.e. fresh, stockpiled, composted, or treated). Generally speaking, poultry litter and liquid manure can be high in readily available (inorganic) nitrogen, while solid manure and compost are high in organic nitrogen, which requires microbial action to make the nitrogen available to crops.
Manure treatment, such as composting or solid-liquid separation, changes manure nutrient dynamics, making it more suited for some situations than others. Composting, for example, results in dramatic losses of dry matter and water. The process results in higher concentrations of nutrients in the mature compost. Some of the plant-available nitrogen is lost to the atmosphere and more of the total remaining nitrogen is transformed into an organic form, which requires microbial action to make the nitrogen available to crops. This makes compost a better source for long-term nutrient release.
‘Using book values from the Manure Characteristics and Land Base Code can help you to estimate the nutrient content and characteristics of different manure types and target where and how to take advantage of those nutrients,’ explains Wallace. ‘However, manure or compost nutrient composition varies widely among farms, livestock species, feeding practices, bedding practices, manure types, storage management, environmental conditions, and with time. So getting nutrient contents from on-farm sampling as close as possible to the time of application is best (see sampling techniques for liquid and solid manure for analysis).’
Due to the inherent variability of manure, a single manure sample is unlikely to provide an accurate estimate of the nutrients throughout the pump out of a liquid manure storage structure or from a large stockpile of solid manure. Many samples, properly collected over several years, will provide a better picture of the typical nutrient concentrations in the manure.
‘Once you know the amount and form of nutrients available in your manure or compost sources, you can target the manure to fields, crops, or within a rotation to take advantage of those different characteristics, getting a greater benefit, higher value from those sources.’
- Applying compost or solid manure to fields with low soil organic matter levels will add organic material and improve soil structure more so than applying to fields with high soil organic matter levels.
- Applying poultry litter or liquid manure to fields or crops that require high levels of readily plant-available nitrogen right away may result in better crop yields than applying sources with high organic nitrogen which requires microbial transformation to be plant available.
- Using solid manure or compost in situations when adding late-season nitrogen can boost crop protein levels, as these sources are high in organic forms of nutrients that come available over time through microbial conversion.
- Targeting manure sources and applying in the rotation can maximize the value of the applied manure by looking at the nutrient need/use over time. Targeting allows for nutrient application to match when and what the various crops need.
In addition, field conditions may make a field more suitable for one source of manure or compost than another. Alberta’s manure management legislation, the Agricultural Operation Practices Act, requires surface applied manure to be incorporated within 48 hours unless the manure is applied to direct seeded land or onto forages. In situations where erosion is an issue and incorporation is not required, operations may choose to apply solid manure to reduce the short-term risk of soil erosion. In situations where erosion may be an issue, and incorporation is required, producers may not want to apply manure at all to avoid soil disturbance.
‘Knowing the nutrient contents of various manure or compost sources, soil properties of the receiving fields, and crop nutrient needs will help you select the right source for the right field to optimize nutrient use, avoid nutrient loss and offset fertilizer cost,’ says Wallace.
For more information, connect with the Ag-Info Centre:
Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)
Toll free: 310-FARM (3276)