Manure is a valuable source of nutrients, so it’s important to retain as much of that manure on the field as possible. In this podcast episode, UW-Extension specialists discuss ways to prevent nutrient loss after fall manure application.
Liz Binversie, Agriculture Educator, Brown County UW-Extension
Kevan Klingberg, Outreach Specialist, UW-Discovery Farms
George Koepp, Agriculture Agent, Columbia County UW-Extension
Time: 9:38 minutes
Liz Binversie: Greetings, I’m Liz Binversie, Agriculture Educator for Brown County UW-Extension, and today we’re going to talk about preventing nutrient loss from manure application. On the panel is Kevan Klingberg, Outreach Specialist with UW-Discovery Farms, and George Koepp, Agriculture Agent for Columbia County UW-Extension. George, what advice do you have for farmers so they have a better chance of keeping those nutrients in the field?
George Koepp: Liz, a farmer’s goal is always to keep those nutrients in the soil matrix to feed our crops. They want to avoid losses to the atmosphere, to surface waters, and to ground water sources. To do this, they have some tools to help them. The main goal here is to prevent nutrient application loss of that manure after corn silage harvest, after soybean harvest, after corn grain harvest, after last alfalfa harvest, and again making sure that we do this all prior to the ground freezing in the fall or winter. A couple of tools that farmers have to use are to use restriction maps, again, to identify prohibited areas of application. Again, we want that manure to stay pretty much where we put it. We obviously don’t want to apply in established grass waterways. We need to stay away from sinkholes. Stay away from surface water, obviously, non-harvested cropland or buffer strips, 200 feet away from wells in a CAFO or 50 feet in private wells and smaller farms. We really don’t want to be applying manure to saturated soils. It’s going to sit there and not go into the soil the way we want it to. Again, we have to watch out for certain areas where we know that we have fractured bedrock. Again, our restriction maps really do a nice job of helping and pointing out those locations where we want to stay away from spreading manure at critical times. Another tool that farmers have available to them, as well as for professional nutrient applicators, is the manure advisory system that’s been put out there in Wisconsin. It really has some great things to help farmers and nutrient applicators plan their applications so we can avoid runoff risks as much as possible. If you go to this website, it actually shows a very nice map and shows day-to-day risk of runoff across Wisconsin, typically for a 3-day period all during spring, summer, and fall. In the winter time when the ground is frozen, it shows a 10-day period in the winter that gives us an idea of when snow melt might occur. We know if we spread manure on top of snow, it’s probably going to run off if that snow melts too quickly. Again, this uses the national weather service forecast methods. It considers precipitation, soil moisture, individual water basin characteristics, steepness of the slopes and those kinds of things, and it gives recommendations for managing manure during high runoff risk times. There are several different tools on this website that can help farmers. Another part of that manure management advisory system, you can click onto another spot and it helps you do the 590 nutrient management planning, which helps you develop your own interactive online 590 restriction maps for your individual properties. The Department of Ag, Trade, and Consumer Protection has the GIS layer files on there, so again, lots of different information can be brought together to help you plan that. Also on this website are maps for soil temperatures and frost depths. Again, helping farmers later on, when can we get in there in the spring? It also has a snapshot of previous runoff risk advisory forecast maps. Lots and lots of information is available to farmers and professional nutrient applicators to determine when and where to apply that manure. Kevan, another tool that we have out there is the use of cover crops, so how can farmers best use cover crops to help keep those nutrients in place after applications following corn silage?
Kevan Klingberg: Thank you, George. That’s a very popular choice that many farmers are taking a look at now. And again, we want to make sure that when corn silage is harvested and we’re putting manure down to empty our pits and get ready for fall as a nutrient source for the next year, that we keep as much of that manure nutrient on the field as possible. Using cover crops is an excellent to do that. We need to remember that there’s a short window between when the corn silage comes off and freeze up. Using any of the small grains is probably one of the best ways that we can do cover crops after corn silage. Winter rye is an example of one of the cover crops that will continue to live through the winter and give cover as well as potential forage next spring. If we want use something like traditional oats or traditional barley—the spring oats, spring barley–they’re an example of a cover crop that can be planted and we know that they will winter kill. So next spring, there’s going to be residue. It won’t green up. It’ll be dead, but it can be planted right into as well. Again, we’re looking for maintaining residue—green material in the fall and potentially into the spring—that’s going to help mitigate the energy that the rain drops have, as we want to prevent soil erosion. Cover crops are also going to be a really excellent way to begin to utilize some of the manure nutrients that’s available and potentially recycle some of the nutrients. Neither of these small grains, whether it’s the rye or the oats or barley, are going to particularly give us a nutrient credit. But using small grains right after corn silage is a really good way to develop some type of a ground cover and also to begin to use the nutrients to get taken up into the small grain grass materials so that it can be recycled or let loose again next spring. No till is a really easy way to establish these small grains. There’s a lot of farmers who are also experimenting with just broadcast spreading either before or after the manure is put on. Any way that you do it, these small grain grasses are going to be able to provide some type of a quick cover and, also in the case of rye, provide cover for next spring during the time period where snow is melting and the early spring rains are coming. So yes, George, it is a really good way for dairy farmers who are taking corn silage to continue to minimize soil loss as well as continue to utilize the nutrients that are available from manure.
George Koepp: Alright thanks, Kevan. In summary, we’ve got several tools that farmers and nutrient applicators can use. Number one, use the spreading restriction maps to plan best places to spread that manure. Number two, use the manure advisory system to plan the best time to apply that manure, and number three, plant small grain cover crops to keep and hold the manure and soil in place until the actual crop needs the nutrients the following year.
Liz Binversie: Thank you Kevan and George for these excellent tips. If you’d like to reach them, you can do so by email. Tune in next time for the fifth and final podcast episode about strategies for this year and learning how you can deal with a full pit in a wet fall.