Starter fertilizer for corn has generated a lot of press and coffee shop discussion this past winter.  Most of the jargon centered on the need for starter fertilizer or, at the very least, the amount.  These discussions were preceded by a historic rise in the cost of fertilizer and the anticipation that prices would go higher.

     There are several inherent problems with starter fertilizer.  One is simply the name.  Starter fertilizer is a Chihuahua named “Killer” or a pit bull named “Daisy.”  The term “starter” implies fertilizer needed for early season plant growth.  Although this is true, fertilizer applied at planting often has a much larger and more important role.  Planter applied phosphorus and potassium often is used to replace nutrients in the soil that are removed by the crop.  In other words, the fertilizer is used to maintain the current soil test level.  This function is more of a “finisher” effect than a “starter” effect.  More on this later.

     The next problem with starter fertilizer is perception.  Some define starter as all fertilizer applied at corn planting.  Others consider starter only that fertilizer placed in the seed furrow.  Still others refer to starter as the fertilizer applied in a band that is below and to the side of the seed.  So before any serious discussion of starter fertilizer can begin, there needs to be a clear understanding of perception.  For the purposes of this discussion, I’m considering starter fertilizer as all fertilizer applied at planting.

     Let’s get back to the concept of “starter” versus “finisher” effect.  Starter effect offers the potential for faster seedling emergence and advanced early season growth.  Relatively speaking, only a small amount of plant nutrients placed with or close (in a band) to the seed is needed to accomplish these benefits.

     Faster emergence and early growth translate into yield increases only when growth delays cannot be compensated for during the remainder of the growing season.  Such situations exist when corn is planted late, hybrid maturity is long relative to the planting date, or there is an early fall frost.  The majority of research does not support the notion that faster emergence and early season plant growth always translates into higher corn yields.  In most cases it doesn’t.

     Next let’s take a look at the “finisher” effect.  Again, this is the component of planter applied fertilizer that compensates for crop removal and maintains soil test levels of phosphorus and potassium.  How much fertilizer is needed rests solely the current state of soil fertility as reported in a reliable and current soil test analysis.  Where fertility levels are very high or excessively high, investing input dollars in crop removal nutrients makes no economic sense.  Not investing in nutrients when soil tests are optimum or below doesn’t make economic sense as well.  In short, a good set of soil tests has the potential to save crop producers a lot of money in 2009.

     Can planter applied starter fertilizer be reduced or eliminated in 2009?  Only with a good set of soil tests can this question be answered.  The answer is not always “yes” or always “no.”  If the soil test level is very high or more, only consider a small amount (10 lbs. per acre each of nitrogen and phosphorus and 20 lbs. of potassium) of “starter” effect fertilizer if crop maturity is a concern.  This is also the situation where a nitrogen only starter is worthy of consideration.  If soil test levels are in the high category, apply fertilizer with the planter up to about one-half crop removal.  For soil test levels at optimum or below, apply nutrients equal to crop removal.