Thursday, October 24, 2019
Manure, waste or resource, is a question I like to ask when I get the chance to step in front of a class and hear what students have to think about the topic. Generally, I get enough answers of both to be satisfied. Manure can be a waste and it can be a resource: it comes down to how we manage it. It is a simple answer, but the best ones often are.
1. Students work to develop a manure management plan for a beef operations.
So what is a manure management plan? This is a tool that estimates all the manure a facility is going to generate and then looks at the crop fields available to make a determination about how much manure could be applied to each field in any given year, based on both the risk of phosphorus transport and the nitrogen needs of the crop. In the state of Iowa, they are required for confinement animal feeding operations with more than 500 animal units, which is 1,250 finishing pigs. Manure management plans can serve as a tool for the farm as a means to estimate manure application rates, but also a tool for society to ensure the farm has the capacity to manage its manure in a way based on legal standards we have defined as environmentally acceptable.
The original framework for these plans was developed in the early 1990’s and has been modified slightly. The livestock and the manure industry looked a bit different at those times. For example, manures typically had about $8-$12 per 1000 gallons nutrient value in it, whereas now we typically average closer to $30. While this change may not sound like much, when compared to typical application prices of $10-$20 per 1000 gallons, those differences can make a world of difference, changing it from a fertilizer source that isn’t cost effective for the farmer to utilize to one that is.
When manure plans were first developed, some farms manure looked like a product we had to dispose and find a way to manage, while minimizing environmental risk. Today, we have a greater opportunity, manure can be a resource, if we can find ways to manage it as such. Are the production systems we use today perfect? No, none are. We need to continue to get better and improve them to ensure livestock farms can remain an important part of our landscape in the future. We have made progress, and have to continue to do so in the future.
Manure management plans are typically filled out using the yield goal method. In this method, farmers determine a yield goal for each of their fields. This is a number selected based on previous yields either for that field or that county, and then multiplied by a nitrogen use factor, typically 1.2 lb N/bu of corn yield expected, less any legume credits their field would have. Is this method perfect? No. I’ve expressed different thoughts about it before. In a previous blog, I compared how yield goal method and MRTN estimates nitrogen application rates, looking at how corn nitrogen content per bushel has changed and what it means for these methods. In this blog, I looked at how the estimates compared in each county. However, nitrogen application is a complicated topic, related to weather, and soils, and timing, and there is a lot that goes into this decision.
Is there room for improvement? Absolutely! Take credit for those nutrients. Get manure to fields where all the nutrients have value. Work to minimize uncertainty in nutrient supply by testing the manure for nutrient content, calibrate the equipment and check the flow meter. Look at application uniformity, inject or incorporate, and try to apply at appropriate times. Will this alone solve our water quality concerns? No, but they are things we can do now to maximize the value of manure in our operations and take steps towards environmental improvements and continuing to build trust in using manure nutrients.