Corn production has several key factors which directly influence the success of the year and cost of production:

  • soil pH

    nitrate nitrogen content preplant

  • 0" to 6" soil phosphorus levels

  • preplant potassium levels

  • the type, rate, and timing of nitrogen applications

  • complete plant nutrition profile based on tissue tests


All of these factors directly influence decisions of specific inputs both preplant and during plant growth.  Without soil and tissue testing it is impossible to have these factors correctly adjusted for plant needs.  A $6.00 test for nitrate nitrogen present within the week of planting will determine how much additional nitrogen is needed to reach a specific yield per acre.  This test can either increase the need for N or reduce it  based on what is found and in either case save well more than the test costs or increase yield and return a higher profit.   Properly crediting the soil bank in season for legume is also a must.  Depending on the legume, yield, pH of soil, or mosture present in the growing season extremely variable amounts of nitrogen can be released.

Soil phosphorus levels diverge greatly from 0" to 2" depth versus 2" to 6" depth.  This is very important specifically when top production occurs or a dry period occurs during development because soil phosphorus levels may be insufficient at lower depths in the root zone.  Phosphorus does not usually move, without direct physical placement, more than 1.5 inches from point of placement.  So, dry fertilizers spread on surface under no or minimum tillage will remain at shallow depths and across years will be a direct factor in yield loss over time. 

Potassium is critical for corn production. Raw potassium numbers may be sufficient, but without sufficient saturation levels in the soil other cations can be used to replace K limiting yield, development, and potentially increasing disease.

Types of nitrogen, when it is applied, what format is is applied in (dry or liquid), and volumes per application should take into effect soil type or more specifically CEC.  Lower CEC soils cannot 'retain' large amounts of N.  Normal high rate applications found in most corn production in early season will have some leaching losses due to low CEC soils.  No nitrogen is worth waisting nor is the money it took to buy it.

Soil testing and plant tissue testing are critical to identifying the nutrient, amount of nutrient, and placement or application method for all crops, but especially those which respond to direct fertility.