By Russ Quinn
DTN Staff Reporter
OMAHA (DTN) -- When farmers consider adding manure to their fields, they weigh its benefits against some of the negatives. They need to be aware of the amount of nutrients they are adding to meet the crop's needs, as well as deal with manure's odor and weed concerns.
Some options to help manure fit better into farmers' management plans include composting and using manure additives.
The main advantages of composting are that it concentrates nutrients, kills weed seed which could be present in manure, and the compost has virtually no odor when it is applied to fields, said Sarah Sellin, resource conservationist with the Natural Resources Conservation Service (NRCS) Water Quality Team based in Norfolk, Nebraska.
Composting involves mixing corn stalks and/or straw with the manure, then wetting it down. The mixture is allowed to sit for a certain amount of time, while being regularly turned to allow air to reach it.
During the heating process of composting, any pathogens in the manure are removed. This is important if the compost will be applied to food crops, Sellin said.
The resulting compost is rich in nutrients, mainly nitrogen in the form of ammonium which is used by plants. Much like straight manure, compost also improves physical properties of soils.
When making compost, it is important to correct the carbon-to-nitrogen ratio, Sellin said. "Most of the carbon-to-nitrogen ratio is 25-to-1, to maybe 40-to-1," Sellin told DTN. "It breaks down into a finer product which is easily managed so that even gardeners or golf courses can use (it)."
Dan Davidson, DTN contributing agronomist and a Nebraska farmer, said he has used some compost on his own farm as a fertilizer. He bales corn stalks for a neighbor who mixes the bales with paunch manure from a local cattle slaughter facility.
The mixture is turned often, put into windrows, and allowed to sit five to eight weeks. Then the compost with its nutrients is placed on fields in place of commercial fertilizer.
"Compost is an excellent source of nutrients," Davidson said.
MORE MANAGEMENT NEEDEED
Composting does have drawbacks. Much like manure, more management is needed.
During the composting process, the product loses roughly half of the nitrogen manure would contain. Farmers need to apply more tons of compost per acre to make up for the lost nitrogen, Davidson said.
"The biggest issue I see with composting would be transportation," he said. "The compost I got is fairly lightweight and right across the road. If you had to truck it a long ways, I don't know if you could haul enough of it to make it worth it," Davidson said.
Other disadvantages with composting would be the time needed to properly manage the windrows, the large amount of area needed to row compost, and the increased cost of specialized equipment, such as windrow turners.
PRODUCTS IMPROVE MANURE
A new generation of products can be added to manure to assure that nitrogen is the correct form for plants and that these nutrients are available longer at the root zone where the plants need it most.
Nitrogen stabilizers keep nutrients applied to the soil in the form available to the plants. One form of stabilizers is urease inhibitors: They help reduce the loss of ammonia to the atmosphere. The other type of stabilizer is nitrification inhibitors, which keep bacteria in the soil from converting ammonium into nitrate, which can be lost to leaching. (See http://bit.ly/…)
The most well-known urease inhibitor is Agrotain. Nitrification inhibitors include products such as N-Serve and Instinct. More Than Manure Nutrient Manager (MTM) is another manure management product which reduces nitrogen loss from leaching, volatilization and denitrification, as well as reducing phosphorus lock-up.
Applying manure close to planting will reduce potential losses of nitrogen to groundwater or by volatilization, said Jose Hernandez, an Extension livestock nutrient management educator at the University of Minnesota. He said the most efficient time to apply manure is in the fall or in the spring.
"We recommend ... (applying) manure when the soil temperature is 50 degrees (Fahrenheit) or lower to keep the nitrogen in the ammonium form," Hernandez told DTN. "Once the nitrogen converts to nitrate, it can be easily lost by denitrification or leaching, especially when there is not a crop to use the nitrate."
Products such as Instinct allow farmers to apply manure in temperatures above 50 degrees, so there's a wider window of application, especially in the fall, he said. Instinct and N-Serve are the same compound except Instinct is formulated for UAN solutions and for liquid manure, he said.
Research has been done at the University of Minnesota on Instinct with manure. Hernandez said the product is effective in keeping the ammonium in the soil. Similar crop yields have been achieved with early application of manure with Instinct in the fall when the temperature was over 50 degrees, as compared with later manure applications without Instinct in the fall when temperature was below 50 degrees.
"The product can be a form of insurance to keep the nitrogen in the soil, but it can be a significant cost to the farmers," he said.
Jamin Ringger, a crop and hog farmer from Gridley, Illinois, has about 500 sows on his central Illinois farm. He has used Instinct while applying manure in the past, but he no longer uses the product.
"We just didn't see any real results from using it," Ringger told DTN. "You put in two gallons of it to 6,000 gallons of manure; to me, it just didn't really help us much."
Ringger said he still sees the benefit of nitrogen stabilizers, despite deciding to no longer use the product on his farm. Every year is different and products like this could aid hog producers who apply manure in falls where temperatures stay above 50 degrees longer, he said.
Wanda and Chuck Patsche, who feed 4,400 hogs a year in a wean-to-finish hog operation near Welcome, Minnesota, haven't used any manure additive products on their farm yet, but may do so at some point.
"We have looked at these types of products seriously," Wanda Patsche told DTN. "I know these products will stabilize nitrogen in the soils, and if we think they could help us in the future, we could very well use them at some point."
Russ Quinn can be reached at firstname.lastname@example.org
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