Tips for Effective, Economical Fertilizer Use



There’s no doubt that money spent for fertilizer will be a major consideration for crop production in 2016.  Growers are looking at fertilizer use as one important input that will help to keep costs in line.  With fertilizer costs as an issue, this might be a good time to emphasize some practices that will result in effective, economical fertilizer use for 2016.


Pay Close Attention to Nitrogen Rates

Nitrogen is the major expenditure for fertilizer for most crop producers.  Suggestions for rate of nitrogen to use for corn have changed.  The old standard was to multiply yield goal by 1.25 and then subtract nitrogen credits such as the amount of nitrogen in manure.  Beginning in 2006, that approach was changed throughout the Corn Belt.  Now, it’s important to divide the cost of a pound of nitrogen by the value of a bushel of corn.  Many times, this ratio is 0.10.  If this is the ratio or close to it, corn following soybeans should be fertilized with 110 to 120 lb. of nitrogen per acre.  Yield goal has disappeared from the calculations.  Using the same ratio for corn following corn, the suggested rate should be in the range of 150 to 160 lb. on nitrogen per acre; then subtract the nitrogen credits.


Split applications of nitrogen are the most effective.  This practice is being emphasized by the fertilizer industry in recent months.  So, the fertilizer industry as well as the equipment industry is getting ready for split applications.  In addition to being economical, split applications will have a positive impact on the environment.


Band – Don’t Broadcast

Some serious consideration should be given to the placement of the nutrients that are not mobile in soils (phosphorus, potassium, zinc).  These nutrients can either be broadcast and incorporated before planting or applied in a band near the seed at planting.  In general, rates needed for optimum production are cut in half if used in a band at planting instead of broadcast before planting.  A banded application of phosphate is a positive step toward environmental quality.  Application of a pop-up such as 10-34-0 is a good way to apply phosphate in a band.


Ignore the Foo-Foo Juices of the World

In past years, various products have been marketed with grandiose claims for saving fertilizer.  The large majority of these products did not work as claimed and have disappeared from the market.  Now, instead of products, there are foo-foo concepts that are being promoted.  Most are fictitious.  So, how do you sort these from reality?  You ask for advice from someone who might be knowledgeable about the concepts.  Those most informed would be Certified Crop Advisors and Extension personnel with statewide responsibilities.


Don’t Buy Something That You Don’t Need

It seems that there’s always a “push” to buy something that you don’t need.  A good example would be a “push’ to buy the micronutrients – manganese and boron.  Research has shown that there has never been to the use of manganese in Minnesota.  Likewise, use of boron has not improved crop production on the vast majority of the soils in the state.  Although some advertising would lead you to believe that these two nutrients should be added to every fertilizer program, they are not really needed – save your money.  Likewise, some promote an ideal balance for calcium, magnesium, and potassium.  This is just another ruse by promoters to sell product and spend your money.




Pay Attention to Soil Test Results

Results of the laboratory analysis of soil are the only way to evaluate the relative levels of available   nutrients in soils.   These levels have been identified as very low, low, medium, high, and very high.  If levels are low or very low, the immobile nutrients (phosphorus, potassium, zinc) can either be broadcast before planting or applied in a band at planting.  Rates needed for each placement can be provided by University of Minnesota Extension.  For phosphorus, anything less than 10 ppm (Bray test) or 8 ppm (Olsen test) is considered to be low.  For zinc, anything less than 0.5 ppm is low or very low.  For potassium any value below 80 ppm is considered to be low.


Broadcast applications will not be economical if nutrients are in the medium range.  For phosphorus, this is 10 to 15 ppm (Bray test) or 7 to 11 ppm (Olsen test).  For potassium, this range is 80 to 120 ppm and for zinc this range is 0.5 to 0.7 ppm.  In this medium range use, banded rates only.


If soil tests show high or very high levels, crops will not respond to the broadcast applications of phosphate, potash, and zinc fertilizers.  Use a band application instead.  Application of these nutrients will not be needed at very high soil test values.  Fertilizer use does have to be “locked in” to what was used last year.  There are options for cost effective fertilizer management.  Some are described in the preceding paragraphs.

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