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October 2006

Maximizing Your Manure Investment

Manure can be as effective at supplying nutrients as fertilizers, but its variability means producers need to put some thought into what, where, when, and especially, how manure is applied. The examples provided here are from swine operations, but the factors involved apply to dairy farms, as well.

Natalie Rector
Extension Manure Nutrient Educator
Jon Rausch
Ohio State University

Land application of manure is costly, but can be financially worthwhile. This article provides an example of a hog finishing operation with manure utilized in three different scenarios with and without incorporation. The value of the nutrients supplied to crop production ranges from $20 to $105 per acre. There is no such thing as a “typical” manure sample, so laboratory analysis should be done. In the examples, analysis shows that this hog manure provides 50 pounds of total nitrogen (N), 20 pounds of phosphorus (P), and 22 pounds of potassium (K) per 1,000 gallons. Of the total 50 lb of N, assume 41 lb are available when incorporated, but only 5 lb are available when surface-applied under hot-dry conditions. What makes the value of the captured nutrients so variable?

Example 1

In example 1, the manure will be injected ahead of corn; the N will be fully credited, and the soil test was low in P and K. Therefore, all of the N, P, and K value in the manure is realized. These values could be used with a neighboring crop farmer who probably has some corn fields requiring P and K. These values also could be typical of a livestock producer who has lower soil tests on fields that are considered too far and too costly to haul manure to.

More than 85% of the dollar value of the N is lost when manure is not incorporated. It becomes apparent that to fully value manure nutrients, the N needs to be managed either by mechanical incorporation or by relying on cooler temperatures and precipitation to retain the N. Of course, there will be a cost associated with injection or incorporation.

Example 2

In example 2, the soil tests are high enough that no P or K would have been recommended. Therefore, only the removal values of these nutrients and all of the nitrogen are credited. In a corn/soybean rotation where manure is targeted ahead of the corn crop and no manure is applied during the soybean season, the manure values for P and K will average below crop removal over the life of the rotation.

Example 3

In example 3, the manure was put on ground going to soybeans. Even though soybeans have a very high need for nitrogen, they capture it from the atmosphere when not supplied by fertilizer or manure. They will utilize manure nitrogen if it is applied, but a farmer would not normally purchase commercial fertilizer nitrogen.

There is an $85 per acre difference ($105.53-19.92) from incorporated manure on corn in system 1 compared to applying manure to soybeans in system 3 based on current fertilizer prices and application choices.

Growers have several ways to manage these systems for greatest benefit. Current soil tests help direct manure nutrients where they are most need. Current manure sampling estimates the nutrient concentrations and helps in identifying the correct application rate.

Managing Manure Application

Manure needs to be treated like fertilizer and the application needs to be uniform across the field. Despite the potential variability of manure, it produces yields comparable to or even greater than synthetic commercial fertilizer.

Despite the value of the nutrients, hauling can cost more than the economic value of the nutrients, especially with typical farm-sized equipment. Fuel and energy prices have increased fertilizer costs making manure nutrients more valuable. Gaining full benefit from manure nutrients may mean hauling it farther and using injection or incorporation— all of which increase fuel consumption.

Manure management is costly, but the economic incentive to dedicate resources to this task is increasing. Producers need to consider the complement of equipment needed to be efficient in hauling manure to the most needy fields in a timely manner each spring. After considering time, efficiency and fuel costs, it may make sense to work with custom applicators, develop partnerships with neighbors, or evaluate their current equipment.





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