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Guest Opinions

Manure Management can be Sticky – Part One

Written by Meryl Rygg McKenna

Editor’s Note: This is part one of a two-part article. Look for the second installment in next week’s Roundup.

Fifty years ago, in diversified farming areas where cattle and grain crops co-existed on a relatively small scale, it was common to see a tractor pulling a manure spreader, fertilizing fields. Now, it is more common to see dry, granular commercial fertilizers being applied by large trucks or tractor-drawn spreaders.

Given the large number of livestock in certain regions in Montana and Wyoming, combined with tight margins in both crop and livestock operations, well-thought-out manure management is more important than ever.

How can a grower use manure as a resource most productively?

Planning is a priority

Manure is a good source of organic matter, nitrogen (N), phosphorus (P), potassium (K) and micronutrients (micros). All of these elements are necessary for healthy plant growth. Adding manure to soil increases organic matter, which can improve the soil’s structure, water-holding capacity, infiltration and soil microbe activity.

Nutrient values in manure can vary widely, depending on type of animal, age of manure, whether bedding or other material such as weed seed is in the manure and other factors. A manure analysis is a low-cost method – around $60 – of obtaining the nutrient content of manure.

Once the nutrient value of manure is known, a plan is needed that will include where and when to apply manure, how to estimate the best application rate and which crops might benefit most. These things – plus a plan to protect water quality – make up a Nutrient Management Plan (NMP), according to Tommy Bass, Extension associate specialist who advises on manure management.

There are three types of manure NMPs – one for individuals, one submitted to the state Department of Environmental Quality for a permit and one developed by the Natural Resources Conservation Service (NRCS). A permit NMP is required only for animal feeding operations and their related farm enterprises. An NRCS NMP is a requirement of certain USDA cost-share programs. An individual NMP may be fairly simple, while a permit NMP may be quite involved.

Management plan benefits

Lenders and insurers increasingly ask for some sort of management plan to reduce liability on animal feeding operations and some ranches. An NMP can answer that need. Help for creating NMPs may be available from consultants such as Certified Crop Advisers, USDA Natural Resources Conservation Service or Extension.

One good thing about an NMP is that growers are required to keep records and sample their soil, said Neal Fehringer, a certified professional agronomist and certified crop adviser (CCA) from Billings, Mont. The process makes growers more aware of the impact that applying manure has on crops and the environment, ways to use it wisely and how to make the most of its benefits.

Giving manure away is a strategy for simplifying a NMP for permitted animal feeding operations. Certain aspects of the plan are still required to document other Best Management Practices (BMPs) and water quality protections.

Incorporating manure

Tilling the soil in some way is very important after applying solid manure. If manure is applied to the surface but not incorporated into the soil and an intense rain or flood-irrigation occurs, manure can leave the field and end up in streams, rivers and wells. 

In addition, nitrogen volatilizes into the atmosphere if it is not incorporated into the soil within 48 hours of application. Loss of nitrogen into the air means less is available for plants, and there is more manure smell in the neighborhood. More nitrogen in the atmosphere means it is deposited with rain in non-intended areas, thus increasing nitrogen in waterways, mountains, etc. From an economic standpoint, more nitrogen loss to the air means more money gone with the wind.

Soil injection of liquid manure, common on hog and dairy farms, is a style of application that is quickly gaining popularity. Its benefits include significant reductions in the negative effects of compaction from narrow-spaced truck passes, nitrogen loss, odor and tilling of the soil. It is efficient from a time-management perspective but is expensive due to high equipment costs. While several methods of injection are in use, growers have reported being extremely happy with agronomic production where the manure has been knifed into the soil.

Application of liquid manure through pivots and wheel lines has also been used, Fehringer said. It is a low-labor method with some smell downwind during application. Water moves much of the nutrients into the soil so odor after application does not occur. Care must be taken to prevent runoff from the field into surface waters.

In the next installment of this article, McKenna discusses considerations for using manure as fertilizer and the value of manure.

For more information on certified crop advisers, or to find one near you, go to certifiedcropadviser.org.