By Robert Meinen
As the COVID-19 emergency continues to evolve milk dumping has become a reality for some dairies. In response to these unprecedented developments Governor Wolf has authorized Temporary Suspension of certain manure and waste land application regulations through June 1, 2020. The suspension will be reevaluated for continuance at that time. In turn, the Pennsylvania Department of Environmental Protection (DEP) has released guidance entitled Emergency Land Application of Milk Under COVID-19. The guidance is very thorough and provides great practical perspectives beyond just the “rules”. Anyone that finds themselves involved with land application of milk or manure-milk mixtures will likely benefit from reviewing the document prior to tackling the job at hand.
Direct land application of milk is possible under the guidance and may be the best solution for farms that do not have liquid manure storage or liquid manure application equipment. When sensible it is recommended that the milk be mixed with manure before land application. Mixing will help to dilute the milk’s nutrient content which is higher in nitrogen (N) and phosphorus (P) content than most liquid dairy manures. The N and P in milk are also highly available to crops and susceptible to runoff. Mixing with manure will also bring some organic nutrients from the manure that will release slower through the season to more closely match crop demand, so there are both agronomic and environmental benefits to mixing. While not mentioned in the guidance, producers that cannot feasibly mix milk with manure may want to consider application of milk at a low rate and round out the balance of expected crop nutrient need with a supplemental manure application.
The DEP guidance provides a maximum application table that is based on the percent of milk and the percent of manure. Milk that is not mixed has a maximum application rate of 4,500 gallons of milk per acre, a rate that will provide nearly 200 pounds of N per acre. Many applications may need to be conducted at a lower rate since the maximum rate could easily exceed N requirement of the crop, something that is prohibited by both the guidance and law.
There are a few other important considerations for land application including the expectation of foul odors as milk degrades, promotion of fly propagation, cautious setback adherence, nutrient or manure management plan adaptation, and possible clogging of application equipment. When mixing milk into a manure system it is recommended that the milk be added after treatment steps like separators. If possible, add milk directly to the storage so it is not flowing through manure delivery systems where it can may lead to films that cause odors and flies on the farmstead. The best scenario on crusted storages is to add the milk below the crust as the crust will help to prevent odor release.
Source : psu.edu