Attention Crop Farmers: Fertilizer Value of Milk
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By: Karl Czymmek
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Significant quantities of surplus milk from NY’s dairy industry may have to be land applied in the coming weeks due to unprecedented market disruptions created by the COVID-19 emergency.
Milk has fertilizer value and crop farms may be able to take advantage of surplus milk for a portion of crop fertilization needs, especially if located near one or more dairies. Every 1,000 gallons of milk contains 44 lbs N, 18 lbs P2O5 and 17 lbs K2O. An economic value can be placed on these nutrients based on the following approximate fertilizer prices: Urea at $330.00/ton, DAP at $400.00/ton and Muriate of Potash at $380.00/ton. Using these values, the total N-P-K nutrient value of milk is $27/thousand gallons. A 5,000 gallon per acre application of straight milk delivers nearly $135/A of N-P-K that is readily available to plants. Milk also contains other nutrients such as sulfur, calcium, magnesium and zinc that have not been valued in this calculation. Further, there is some evidence that the land application of milk may significantly improve soil health by supporting bacteria and fungi that live in the soil.
Like many things, there are some other factors to be aware of. Milk that has been mixed with manure or that sits for very long in storage will be odorous, and if mixed with manure the resulting product will have a different nutrient content. Relatively short hauling distances will help make the most economically efficient use of the fertilizer value of surplus milk as transportation costs can quickly offset the value. Also, care should be taken to ensure that milk does not have offsite impacts from runoff. Injecting or incorporating milk into the soil soon after application will help to reduce odor and runoff risks.
Normally, land application of food processing waste, such as surplus milk coming from a processor, that is NOT done under a CAFO Permit requires a Part 360 registration from NYSDEC. Due to the COVID-19 emergency, DEC has issued a memo indicating that the agency will not be enforcing this requirement through October 1, 2020, as long as the land applications follow the technical guidance in Provisional Guidance: Using Surplus Milk as Fertilizer Due to the COVID-19 Emergency. The guidance is also helpful for those land applications of surplus milk transferred directly from one farm to another that would not otherwise need a Part 360 registration.
The DEC letter and Ag and Markets guidance can be found at: tinyurl.com/milkasfertilizer.
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