Calibrating Beef Manure Spreaders Saves Money and Protects the Environment

Kris Kohl, Agricultural Engineering Field Specialist, Northwest Area

Problem Statement:

Beef producers have a valuable resource in the by-product of their operation which is manure.  Manure is a stable, organic fertilizer that contains the same nutrients as the corn and soybeans used to feed the cattle.  While producers realize that it is a valuable by-product of their operation, producers are reluctant to rely on its nutrients because of the variability of the product, and not knowing how much is actually going on the soil.  Calibrations in the past required weighing the spreader on scales and measuring the area spread, both of which are very time consuming and therefore rarely done.  When manure or fertilizer is over applied, it can end up in surface or groundwater causing environmental problems.

Programmatic Response:

To aid producers and encourage beef producers to calibrate manure spreaders, ISU Extension developed a simple method using a plastic sheet that is one two thousands of an acre.   This sheet is 21.78 square feet and represents about twice the area that corn plant roots can explore during a growing season.

The sheet of plastic is placed on the soil prior to land application and the producer spreads manure over it.  The plastic with manure is then weighed and a manure sample collected from the plastic sheet and sent in for lab analysis.  The weight of manure on the plastic sheet in lbs. will then equal the application in tons per acre, making it simple to calibrate.


ISU Extension has started a program to help beef producers improve their manure management using the plastic sheet calibration method.  To date, four calibrations have been performed.  The results showed a manure application rate that was slightly below the nitrogen rate based standard manure book values.  However, when the results of the manure test came back, they were higher than book values resulting in an adequate amount of fertilization from the manure application.

Producers comments included, 
        This was so simple and fast, I should have been doing this for years
        When I calibrate and know here Im at, then I can save on fertilizer.

This program is helping producers save money that would have been spent on fertilizer and helping to protect the environment by keeping it out of the water.

January 2007
140 - Iowa Beef Center

Page last updated: January 30, 2007
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