April 17, 2003

 

Think Resource, Not Livestock Waste, NDSU Specialist Urges

Farmers in the region need to stop thinking "livestock waste" and start learning better ways to use a "manure resource," says a specialist with the North Dakota State University Extension Service.

"Generations of farmers have known that manure application improves the soil and increases crop production," says Charles Linderman, a livestock waste management specialist at NDSU’s Carrington Research Extension Center. "But large acreages and relatively inexpensive commercial fertilizers made it seem impractical to spend much time or money on manure utilization. Manure became a disposal problem, and in our efforts to be more sophisticated and genteel, we coined the euphemism livestock waste."

The shift away from using manure as a crop input was hastened as livestock production became specialized and animal numbers more concentrated, Lindeman explains. The resulting concentration of livestock waste has caused some negative impact to water quality and attracted the attention of the general public, lawmakers and regulators. "Now it seems everyone is concerned about this waste problem," he says.

Consequently, under new rules of the U.S. Environmental Protection Agency, some animal feeding operations will be classified as Concentrated Animal Feeding Operations or CAFOs. Most CAFOs will be required to land apply manure nutrients to be used by crops and not impact surface and ground water.

"Typically we expect there to be costs associated with regulations," Linderman says. "However, complying with this part of the environmental regulations can result in an economic advantage rather than a cost. For that reason, even those animal feeding operations that are not CAFOs because of their size or other considerations, should use manure nutrients and organic matter in crop production systems because it makes sense ecologically and economically."

The most likely water pollutants in manure are nitrogen, phosphorus, organic matter and pathogens. "Fortunately, the first three of these also improve the soil and increase crop production. In fact, nitrogen and phosphorus are the two elements most often added to the soil as fertilizer. If manure nitrogen and phosphorus can replace purchased inputs, the monetary worth of manure can be calculated. Rising fertilizer costs make manure nutrient value even more important," Linderman says.

Two-thirds of the producers who filled out surveys at recent livestock waste workshops indicated that they have used manure nutrients to reduce fertilizer purchases. To make the most efficient use of manure nutrients, at least three things need to be considered.

• Manure is a variable commodity from one farm to another. Although "book" values are available to determine the nutrient content of various kinds of manure, the magnitude of variation can be large. An analysis of a sample from stored manure is a much better number to use. A good representative sample requires a large number of sub samples combined to make a composite sample.
   
• Manure is not a balanced fertilizer. Usually, applying enough manure to meet the crop nitrogen requirement will result in excess phosphorus application of several times the crop removal. The most practical and economic solution is to rotate manure application to other fields in consecutive years. Allow enough years between manure applications for the sequence of crops to use the phosphorus applied. The excess phosphorus will remain in the soil unless soil erosion occurs.
   
• Nitrogen in manure is mostly in organic form. It is changed over time to the inorganic form that plants can use. That’s an advantage because the extra nitrogen that is banked in organic form is not soluble and will not leach from the soil. Most manure nitrogen release to the inorganic form takes place over about a three-year period. Thus, fertilizer nitrogen applications should be eliminated or reduced for three crop years after manure application in order to realize the maximum economic benefit of manure nitrogen.

"Farmers of the past knew what recent research has demonstrated: that manure applications increase production more than accounted for by the added nutrients. That is because the organic matter content of the soil increases with repeated manure applications resulting in better soil structure and tilth," Linderman explains. The rainfall infiltration rate is increased which means more water stored in the soil and less runoff and erosion. Soil with more organic matter can also store more nutrients and support more beneficial microbial activity."

For more information on utilizing manure nutrients, contact the NDSU Extension livestock waste management specialist and plan on attending the next manure management workshop near you.

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Source: Charles Linderman, (701) 652_2951, clinderm@ndsuext.nodak.edu
Editor: Tom Jirik, (701) 231_9629, tjirik@ndsuext.nodak.edu