Know you soil test results, whether using manure or fertilizer

Livestock producers should know their phosphorus soil test levels to make decisions on both manure and fertilizer applications.

There are concerns that soil test levels are declining because fertilizer has been high priced for several years and farmers may have backed off of applications.  When focusing on phosphorus (P), lowering your soil tests, especially on a livestock farm, might be a good thing.  

Nobody cares more about your money that than you do, so here are several points to consider as you maneuver between another volatile season of balancing fertilizer prices and good environmental stewardship on farms dealing with manure.

“Soil test values” are not the same as “fertilizer recommendations”.  Do you have a copy of the actual soil test values or only the fertilizer recommendations?  You need to have the soil test levels if you are going to continue to manage manure. 

All soil test values are important, but you need to take control and responsibility for the P soil test levels. The P2O5 value in Michigan needed to build soil levels and maintain yield potential for various field crops is generally between 15 and 40 parts per million (ppm) Bray P1.  If you have fields testing lower than this, make it a priority for them to receive manure.  But fields that have consistently received manure in the past are probably not this low.

When the soil tests levels are between 40 and 150 ppm Bray P1, are you still applying P fertilizer or do your commercial fertilizer recommendations still tell you to?   There are several factors to consider: Do you want to spend money on expensive fertilizer you don’t need? Is it wise to apply manure and also add fertilizer P? Are your P levels increasing each year, thereby threatening your ability, and that of the next generation, to apply manure in the future? 

Manure should not be applied on any field testing over 150 ppm Bray P1 to be in Right-to-Farm compliance or under any other permits or agencies in the state.

Seek a second opinion about your fertilizer needs this spring to take control of your money and your family’s farm future.  The soil tests that you have may be in different units of measure or conducted by various lab procedures.  Contact your local Extension educator to determine the comparable soil test levels and for assistance in developing a phosphorous management strategy for both fertilizer and manure on your farm.

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