This time of year we are thinking about cleaning out the various manure sources that we have on the dairy farm. The calf barn or the heifer and dry cow facility all have some manure that needs to get cleaned out after a long winter. The question is what to do with that manure until the fields are ready to spread. One option that a lot of farmers do is stockpiling the manure. Minnesota Pollution Control Agency (MPCA) recently came out with some guidelines for stockpiling manure.
Stockpiling of manure is one way of storing solid manure (defined as having at least 15 percent solids content or be able to hold a 3-1 ratio when stacked) until it can be applied to cropland as fertilizer. Manure stockpiling sites are covered by the 7020 Rules (Feedlot rules) and are broken into two categories - short-term stockpiles and permanent stockpiles depending on how long the stockpile is stored. Short-term stockpiles must have the manure removed and land-applied within one year of the date when the stockpile was formed and permanent stockpiles can be stored for over one year. The difference is that short-term sites do not need a permit, if the owner is not the owner of the feedlot. Construction of permanent sites containing manure from 300 to 999 animal units requires a construction short form permit.
General rules for stockpiles state that they must be located and constructed such that manure-contaminated run-off from the site does not discharge into the waters of the state. As mentioned before, they must also contain at least 15% solids. This eliminates the possibility of stockpiling true liquid manure. Another point is that the use of rock quarries, gravel pits, or mining excavation sites is prohibited. Also, the size must not exceed a volume based on agronomic needs of the crops on the tract of land on which the stockpile is to be applied.
Additional requirements for short-term stockpiles include: manure removal and land-applied within one year of establishment; a vegetative cover must be established for at least one full growing season before reuse; and a short-term stockpile cannot be located within 300 feet of flow distance to waters of the state, open tile intakes, any uncultivated wetlands which are not seeded to annual farm crops or crop rotations involving perennial grasses or forages. Another point to remember, short-term stockpiles cannot be located within 300 feet of a road ditch that flows to any of the features listed above. A short-term manure stockpile cannot be located within 100 feet of a drilled well or within 200 feet of an augered well.
Stockpiles are also prohibited on land with greater than six-percent slope. Stockpiles are allowed on land with a slope between two and six percent as long as clean-water diversions and erosion-control practices are installed. Stockpiles are also prohibited on soils where the soil texture to a depth of five feet (measured from plow depth) is coarser than a sandy loam as identified in the most recent USDA/NRCS Soil Survey Manuel.
Recordkeeping: Short-Term Stockpile Sites
Recordkeeping is also a component of the use of short-term stockpiling. These records are to be kept on file for three years by the owner of the feedlot at which the manure was produced and be made available to the county feedlot officer or MPCA upon request.
These records should include information on:
Location of each stockpile
Date that it was piled
Volume of manure in the stockpile
Nitrogen and phosphorus content of the manure
Date when the manure was land-applied
If you are considering a permanent stockpile site, the manure needs to be placed on a pad. Construction of a cohesive soil pad means remolding and compacting the soil so that the voids and lift interfaces are eliminated. This kind of work will require the assistance of NRCS or an engineer. You may also have to install a liquid manure storage area to collect the runoff if necessary to prevent manure-contaminated runoff from discharging to surface or ground water.
Stockpiling manure is often part of a livestock operation. Take some time to familiarize yourself with the current laws and ordinances. For more information on stockpiling manure or other manure handling question, contact the MPCA or your local feedlot officer.