Odor and Nutrient Management Newsletter

Fall 2002

Manure application and conservation compliance plans

Kristy York, USDA-Natural Resources Conservation Service, Audubon County

Application of manure and meeting conservation compliance plans has been a controversial issue. The most common method of manure application is by injection or broadcast application followed by incorporation. Injection or incorporation is done to reduce offsite nutrient movement to waters of the state, place manure nutrients closer to the crop rooting zone, minimize odors, and provide some means of tillage. Injection or incorporation of manure can reduce residue, leaving soils bare and more vulnerable to wind and rain erosion. Fall application of manure by using these systems can leave soils bare longer, resulting in potentially greater offsite movement of soil and nutrients. So can manure application and conservation compliance live in harmony? The answer to this question is “yes.”

Manure application equipment.
Manure application equipment.

Through advancements in technology, better ways of incorporating manure are being developed and with the implementation of the Revised Universal Soil Loss Equation (RUSLE), more incorporation options are available to crop and livestock producers. RUSLE is the soil loss equation that is currently being used by the Natural Resources Conservation Service (NRCS). This marriage of manure application and compliance has been demonstrated through field days all over the Midwest.

NRCS employees measure residue after manure application
NRCS employees measure residue after manure application.

At these field days different manure application companies demonstrate their ability to conserve residue under a variety of conditions. They have experimented with different depths of injection or incorporation, speeds, coulters, and residue managers to preserve the maximum amount of residue. The condition the field is left in makes a big difference once the manure has been applied. It is critical many conservation plans that the producer be able to no-till right into the residue after the manure has been incorporated. This approach can be a problem when manure application equipment leaves compacted areas and deep ruts. Although the NRCS prefers to see manure applied to cornstalks instead of bean stubble because the residue levels following corn are better able to withstand tillage from manure applicators, NRCS recognizes that manure application to soybean stubble for the following corn crop is a better use of the nitrogen in the manure for crop production. Soybean stubble is much more fragile and breaks down faster than cornstalks, leaving the slopes unprotected against soil and wind erosion.

The NRCS also is addressing nutrient management through comprehensive nutrient management plans (CNMPs). These plans look at the overall fertility of the farm, the nutrient value of the manure, and recommendations as to how and where to apply the manure. The development of a CNMP includes review of soil types, manure application history, soil fertility level, and identification of environmentally sensitive areas.

For more information about residue management, conservation compliance and CNMPs, please visit your local NRCS office.

Field day attendees evaluate crop residue after manure application
Field day attendees evaluate crop residue after manure application.

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Iowa Manure Matters: Odor and Nutrient Management is published by Iowa State University Extension, with funding support from the USDA Natural Resource Conservation Service through Cooperative Agreement No. 74-6114-8-22. To subscribe or change the address of a current subscription, write to Angela Rieck-Hinz, 2104 Agronomy Hall, Iowa State University, Ames, Iowa, 50011-1010 or call 515-294-9590, fax 515-294-9985 or email: amrieck@iastate.edu. Please indicate you are inquiring about the Odor and Nutrient Management Newsletter. The newsletter's coordinators are Angela Rieck-Hinz, extension program specialist, Department of Agronomy, Wendy Powers, environmental extension specialist, Department of Animal Science, and Robert Burns, Department of Agricultural and Biosystems Engineering; the editor is Jean McGuire, the subscription manager is Rachel Klein, the production designer is Beth Kroeschell, and the web page designer is Liisa Jarvinen.

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