Crucial Considerations for Manure Application
When it comes to manure, it can be viewed as either an important asset that saves you fertilizer and resources, or it more often is viewed as a nuisance that dairies must manage. Every dairy has plenty of manure. A lactating cow will produce around 18 gallons of manure per day. Dairy farmers utilize all their resources, including manure. Let’s take a look at some of the benefits, and considerations when it comes to managing manure on the farm.
Soil and Fertilizer Benefits
As we all know, manure is an excellent source of macronutrients like nitrogen, phosphorous, and potassium. It also adds organic matter to the soil and supports good soil structure, water-holding capabilities, and nutrient-holding capacity. It must be safely stored and handled according to state and federal government regulations.
Manure management is a big part of a dairy farmer’s job. A good rule of thumb for a management plan is that phosphorous will be your limiting factor. Of course, you need to comply with your local, state, and federal regulations when calculating and applying manure. For this reason, if you have your manure analyzed, you will notice that it contains high amounts of phosphorous. Generally, with the phosphorus limits, you can plan on a cow producing enough fertilizer for 2.5 to 4 acres. With phosphorus being the limiting factor, there is current research into separating solids from liquids which allows growers to remove phosphorus, which typically is the highest nutrient that is causing problems. We can conclude that the more solids we can get out of liquid, the better job we can do managing manure. This way we can apply to the nitrogen needs of our crops and pasture without having too much phosphorus applied. Additionally, we’re going to have fewer runoff issues and fewer leaching issues regarding manure.
When it comes to it, manure plays a pivotal role in soil health, enriching it with organic matter, which will increase the water-holding capabilities of the soil and promote good soil structure. We can see manure help increase the productivity of soil from the organic matter. Furthermore, enhanced soil structure and organic matter content significantly boost the soil’s nutrient-holding capacity, reducing the likelihood of valuable nutrients leaching away from the root zone. This natural enrichment cycle stands in stark contrast to the singular nutrient provision offered by synthetic fertilizers, underscoring manure’s holistic benefits to the agricultural ecosystem.
A cornerstone of any effective manure management plan revolves around applying manure according to fertilizer means and adhering to local, state, and federal regulations. This is the part that makes most of us dread manure management.
Cost Analysis
Despite its benefits for fertilization, manure management involves significant financial considerations. A detailed financial survey conducted by the Iowa State University Extension and Outreach Dairy Team, involving experts like Greg Brenneman, Jenn Bentley, Ron Lenth, Kristen Schulte, Leo Timms, and Larry Tranel, shed light on some of the economic factors related to manure management. Their findings, based on a survey of 22 dairy farms in Iowa, revealed that the net cost associated with storing, hauling, and applying manure averaged $104.10 per cow, or approximately $0.45 per hundredweight of milk produced. This figure takes into consideration several variables, including the cost of supplies, labor hours dedicated to manure handling, equipment usage and maintenance, taxes, insurance, and depreciation of machinery and infrastructure. So, in some sense, you save money on fertilizer, but it is not “free”.
It is crucial to understand that this average cost is very variable and it will differ according to you and your operation. A dairy’s specific setup, operational scale, chosen technologies, and proximity to application fields can cause its actual base cost to deviate substantially from the surveyed average of $104.10 per cow. For instance, farms with older, less efficient equipment might incur higher maintenance and operational costs. Conversely, those that have invested in advanced separation technologies or have optimized their application logistics might see lower per-cow expenses. Similarly, the availability of land for manure application relative to herd size significantly impacts hauling distances and associated fuel and labor costs. Farms situated closer to their fields naturally incur lower transportation expenses compared to those that must haul manure over longer distances.
The size of the operation also plays a role in the cost and efficiency of manure management. The type of storage facility whether it’s a lagoon, dry stack, or covered storage also influences expenses. Also, regional differences in labor costs, fuel prices, and regulatory compliance requirements can introduce additional variability. There are so many variables your base cost can very well deviate from their average of $104.10 per cow. The Iowa State University study provides an invaluable financial benchmark, but each dairy farm needs to understand its own cost analysis to accurately identify its expense.
Safety Considerations
As with most things on the farm, it is important to use safety precautions. Daniel Andersen, a professor and extension agricultural engineering specialist at Iowa State University, emphasizes the paramount importance of safety during fall manure application. We’re quickly approaching the time for fall applications. He explains that early application may be justified, particularly to address issues like foam in manure pits or storage concerns. He strongly advises that performing manure removal and agitation when the barn is empty. This will aid in protecting both animals and workers from hazardous air quality. Foam in manure pits is a significant safety hazard because it can trap dangerous and explosive gases like methane. He also reminds farmers to agitate manure thoroughly to break down foam and release trapped gases. This needs to be done in a ventilated area free from potential ignition sources during this process.
Anderson also reminds farmers of the danger hydrogen sulfide (H₂S), a lethal gas produced when settled manure layers are disturbed during agitation, posing severe risks to humans and livestock. Andersen recommends using pit treatments to reduce foam and manage microbial populations, preventing future issues.
Today we live in a complex world of dairy farming, and manure management is one part of dairy farming we are continually managing and improving. Manure often walks a fine line between being an invaluable asset and a burden we have to manage. While every dairy operation invariably produces manure, how you approach it largely shapes its management. Progressive dairy farmers, try and optimize every available resource and recognize manure not merely as a waste product but as a powerful, farm-derived input capable of saving significant fertilizer expenses. On the other hand, for many, the sheer volume and regulatory demands transform manure into a management hurdle. Regardless of your personal perspective, effective manure management is a necessity and a critical component of sustainable dairy operations.
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By Jessica Graham
