Livestock manure is rich in plant nutrients. Manure that is properly applied increases soil fertility and may also improve soil physical properties.
Improperly applied manure can contaminate surface water and groundwater.
Producers must select the relevant best management practices for their crops and land to both maximize nutrient efficiency and protect water quality.
Manure Management Facts
- Manure contains significant amounts of nitrogen and phosphorus.
- Different manures contain high variation in nutrient content.
- Total manure nitrogen is not crop-available the first year of application.
- Nitrogen mineralization from applied manure contributes crop-available nitrogen several years after application.
- Total manure phosphorus is generally considered entirely crop-available the first year of application.
- The organic form of phosphorus found in manure tends to be more soluble and subject to runoff. Other forms of phosphorus may be adsorbed to soil particles.
General Manure BMPs
- Develop a nutrient management plan that credits all sources of crop-available nitrogen.
- Perform manure testing with representative samples to reliably determine nutrient content.
- Apply additional commercial fertilizer to manured fields only when required to satisfy crop nutrients needs.
- In most cases, determine manure application rates on crop nitrogen needs.
Manure Application BMPs
- Do not apply manure to sites with excessive slope or highly erodible soils.
- Limit manure application on frozen or saturated soils.
- Incorporate manure soon after application to prevent volatilization losses, reduce odor, and prevent runoff.
- Create a buffer zone with no manure application 100 ft. from any water supply.
- Plant permanent vegetation strips between surface waters and croplands to filter runoff.
- Apply manure uniformly with properly calibrated equipment.
Manure Stockpile and Livestock Enclosure BMPs
- Locate manure stockpiles and livestock enclosures at least 100 ft. away from any water supply.
- Plant grass filter strips 20-50 feet wide around the downhill side of sloped piles and enclosures.
- Install uphill terraces or diversion channels to redirect and minimize stormwater flow through stockpiles and enclosures.
- Scrape clean and revegetate abandoned stockpiles and enclosures.
- Clean animal enclosures frequently to maintain a firm, dry surface.
- Avoid disturbance of the compacted manure/soil seal when cleaning enclosures.
FAQ
What are best management practices (BMPs)?
Best management practices, or BMPs, are recommended structures, methods, and practices designed to protect water quality. BMPs can provide environmental, agronomic, and economic benefits.
The cost, economic return, ease of implementation, and overall effectiveness will vary from practice to practice. Recommended BMPs may include already widely accepted and utilized agricultural practices.
Every farm is unique and requires a particular combination of practices that meets the needs of the land and the producer.
How are the nitrogen and phosphorus cycles relevant to agriculture?
Nitrogen and phosphorus each naturally cycle through the environment through chemical and biological transformations into various forms. Crop growth is dependent on the forms of these nutrients that are available for uptake and use by plants. Understanding nutrient cycles can help maximize plant growth and crop yields while minimizing harmful losses to the environment.
What forms of nitrogen are available to plants?
Plants can use nitrogen in two forms:
- ammonium-nitrogen (NH4+ – N)
- nitrate-nitrogen (NO3– – N)
What is nitrogen mineralization?
The process that converts nitrogen into forms that are available to plants. Microbes decompose organic nitrogen from manure, organic matter and crop residues into ammonium (NH4+).
Rates of mineralization vary with soil temperature, moisture, and soil aeration.
What sources provide nitrogen to the soil?
- Organic matter: crop residue, manure, biosolids, compost
- Synthetic fertilizers
- Atmosphere: nitrogen fixation, lightning, nitrogen deposition
What is phosphorus mineralization?
The process that converts phosphorus into forms that are available to plants. Microbes break down organic phosphorus and release inorganic phosphates that are available to plants.
What forms of phosphorus are available to plants?
Plants use forms of phosphorus known as orthophosphates:
- H2PO4–
- HPO42-
What is an “agronomic rate” of nutrient application?
A nutrient application rate based upon current crop needs that takes into account already available residual soil nutrients as well as nutrients from all applied sources, such as commercial fertilizers, manure, and irrigation water.