If milk can't be marketed or even used as animal feed, that raises concerns related to where and how it can be disposed. Dairy specialists in the Northeast recently shared information related to milk disposal, should it become necessary.
In many cases, when milk supplies are long, haulers will continue to stop at farms to pick up milk so volume, quality and components can be measured. Then, milk may be moved to manure storage areas, according to Karl Czymmek and Peter Wright, agricultural engineers with Cornell’s PRO-DAIRY program.
Robert Meinen, Penn State senior extension associate, advised dairy producers to develop an emergency action plan for the disposal of milk during these uncertain times. That includes evaluating a producer’s capability to handle it.
“The volume of milk can also deplete manure storage capacity,” he said. “Contingency planning as we move into warmer months should consider when crop land will be available to receive application.”
Down the drain
There have been several social media posts of dairy farmers running milk directly from the bulk tank to a floor drain. Is that a good idea?
“The answer is ‘it depends’,” said Wright in an email to Progressive Dairy. “Many farms with liquid manure storage have plumbed the milking center drains to the manure storage. If that is the case, then putting it with the manure to recycle the nutrients is an OK idea. You don’t want it to go to an under-the-barn storage, as the energy in the milk will accelerate decomposition and could cause gas buildup coming up into the barn.
“If the drain goes to any specific milking center treatment system, then down the drain is a very bad idea,” Wright warned. “The additional energy in the milk will overwhelm any designed treatment system (septic tank, leach field, aerobic lagoon, vegetative treatment area, etc.) The result will be a failed system that will either clog, stink and/or kill off any beneficial biological activity.
“In modern times, it pays to remember that ‘down the drain’ does go somewhere,” Wright said.
What about digesters?
In some cases, milk could be mixed with manure and added to an anaerobic digester before being sent to storage. A biodigester may be an attractive way to decrease the potential of unfavorable odors from disposed milk.
However, dairy farmers should consult with the digester’s manufacturer first, Meinen said. Adding milk may lead to shifts in the system’s microbial community, and some studies show that adding milk to digesters may increase gas production but not necessarily methane content.
Farms with a renewable natural gas contract may have an agreement that prohibits offsite substrates from being added to the digester, Czymmek and Wright note. Dairy producers with an agreement with an outside entity should double check that milk or other substrates are allowed.
Land application concerns
One practical utilization for unshipped milk is land application. While direct land application of milk would be possible, there are several reasons it is recommended that the milk be mixed with manure first.
The same high nutrient value of milk that makes it such a valued food source also comes into play when disposing of it. Milk contains about 44 pounds of nitrogen (N), 18 pounds of phosphorus (P2O5) and 15 pounds of potassium (K2O) per 1,000 gallons.
Whether directly applied or mixed with manure, milk adds to runoff concerns.
“The nitrogen and phosphorus in milk is expected to have higher availability to plants than in manure and be more susceptible to runoff in soluble forms,” Meinen said.
“Milk has a high biological oxygen demand (BOD), meaning that as microbes in water decomposed the milk, they will consume large amounts of oxygen needed by aquatic organisms,” Meinen explained. “Consider cautious setbacks on lands with good conservation practices for manure application with high milk content.”
Depending on the milk-to-manure ratio, there may be a higher-than-normal odor factor from a manure-milk mixture due to the high energy content of milk, especially during agitation and land application, Czymmek and Wright said. Farms with the capability to inject or incorporate the resulting manure-milk mix, instead of surface applications, may be able to manage odors and potential fly issues.
Consider application away from neighbors who could be impacted by odors or flies, Meinen advised.
Nutrient management plans
Beyond physically storing and handling waste milk, environmental regulations are also a factor. Adding a significant amount of milk to manure may mean that nutrient or manure management plans will need to be revised. It is highly recommended that producers communicate with their plan writer and conservation district if large volumes of milk will be added to manure and later applied to farmland.
For concentrated animal confinement operations (CAFOs) with larger manure storage capacities, taking milk produced at other farms must be accounted for. It’s important to talk to your nutrient management planner about how to manage additional nutrients coming to, or not being exported from, the farm, Czymmek and Wright said.
Check for emergency steps related to milk disposal and nutrient management plans in your state. In Wisconsin, for example, the state’s departments of Agriculture, Trade and Consumer Protection (DATCP) and Natural Resources (DNR) recently released joint guidance on the disposal of milk during the COVID-19 health emergency, proposing waivers for some requirements.
For permitted CAFOs, the Wisconsin DNR can reduce the number of days required for public comment for modifications to a nutrient management plan, such as adding fields to land application plans if necessary. For non-permitted farms, the DNR is working with Gov. Tony Evers to waive a requirement to comply with a nutrient management plan if emergency land spreading of milk is the only option available. If finalized, this waiver would be granted on a case-by-case basis made by DNR only during current COVID-19 emergency.
Check ‘waste’ laws
It’s also advisable to check state laws or local ordinances before dumping milk.
In Pennsylvania, for example, statutes define agricultural waste and food waste differently. “In simplest interpretation, if milk does not leave the farm then it will remain agricultural waste and not food processing waste. If it remains on the farm and mixed with manure, the milk can be considered manure,” Meinen noted.
In Wisconsin, milk is considered to be process wastewater under DNR rules governing animal feeding operations. Land application of milk may not cause an unpermitted discharge of pollutants to waters of the state.
Make sure dumped milk is counted
In a recent dairy risk management webinar, University of Minnesota dairy economist Marin Bozic emphasized the need to report any dumped milk volumes, insisting that the milk be identified as “marketed” milk even if there is no payment for it. Those milk weights have the potential to impact a couple of dairy risk management programs.
Dumped milk weights will be reported to the USDA and incorporated into milk production totals, which are a factor used to calculate quarterly milk income under the Dairy Revenue Protection (Dairy-RP) program.
In addition, the USDA National Agricultural Statistics Service (NASS) milk production estimates are used when adjusting annual milk production history increases allowed under the Dairy Margin Coverage (DMC) program.
The USDA recently announced Federal Milk Marketing Order (FMMO) flexibility for the disposal of milk to limit the financial impact to producers. Milk historically associated with an FMMO will be allowed to be dumped at the farm and still be priced and pooled on a FMMO.
Historically, some FMMOs have authorized the temporary pooling of milk disposed or “dumped” on farms or other non-plant locations during the spring flush, when milk supplies exceeded processing capacity. In those cases, dumped milk volumes are reported under a marketing area’s monthly statistical reports and priced at the lowest class price when calculating the FMMO's blend price.
PHOTO: Staff photo.
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