Let’s talk about something super exciting – fertility.  No, not the kind that makes babies (not that kind of show, folks).  Soil fertility!

There has been a lot of attention, especially in Iowa, on water quality and more specifically, nitrate loss in streams and rivers.  From a farmer’s perspective, we have every incentive to keep key nutrients where we need them . . . in our fields.  The problem is, soil doesn’t just stay where we want it to.  When Mother Nature decides to bring us abundant rain, we inevitably lose some of that soil as it washes away.  We also have natural soil erosion that occurs. There are many things we can do to help prevent soil erosion which I’ll talk about at another time.  But my point is, we’re dealing with very complex things . . . soil, weather and volatile nutrients.  The only way nutrients like nitrogen, phosphorus, potassium or lime do us any good is if they are in our soil where our crops can utilize them.

I think it’s a good thing that there’s so much attention on this issue right now.  Keeping nutrients where we want them and minimizing the amount of nitrates that get in our water systems is everyone’s common goal.

So why do farmers spread commercial fertilizers on their fields anyway?  Soils are very complex much like our bodies.  They must have the right balance of nutrients in order to be healthy and productive.  Fertilizers like potassium, phosphorus, lime, sulfur, nitrogen, etc. are essential for our crops.  Each year, the growing crop uses up these key nutrients and they must be replenished so that the soil is kept in a healthy condition and so that next year’s crop will have everything it needs to succeed.

Thanks to incredible advances in the ag industry, we have technology that helps us manage these nutrients better than ever before.  This technology helps us to get a better handle on what nutrients our soils need, when they need them and how much of them they need.  This means we are not over-applying or under-applying fertilizer or nitrogen.  It’s a win-win for us because we have peace of mind, knowing that we’re managing nutrients the best we can and it’s helping us to spend our dollars as efficiently as possible.

On our farm, we are starting to use variable rate prescriptions to spread fertilizer on our fields.  What are variable rate prescriptions?  The traditional way of spreading fertilizer is to take soil samples of the field to determine what amount of phosphorus, for example, the field needs.  Then we apply a flat rate amount of that phosphorus across the entire field (whether the whole field needs that amount or not).  This method is not bad and certainly works very well for many farmers including us.  However, with variable rate technology, we have the ability to break down the field into smaller management zones.  We are able to apply different amounts of fertilizer to different parts of the field based on its needs.  We are micro-managing each area of our fields.


This is a variable rate prescription map for potassium.  The different colors in the field signify different amounts of potassium needed.  The darker orange areas are more deficient and will get more product applied.  


This is the same field but showing the variable rate prescription map for phosphorus.  


Same field again, showing the variable rate prescription for lime.  Lime is used to properly balance soil pH.    

This technology looks at our soil maps and understands how our specific soil types hold water and nutrients.  It also takes into account the topography of the soil and productivity levels of each part of the field.  It figures our yield history into the recommendation as well.  Through the yield data we have been collecting the last several years, the system knows what yield levels the field is capable of and therefore how much fertilizer is needed to achieve our yield goals.

Our goal is to have the most productive soils possible, because, after all, we make our living on productivity.  But the soils and environments we deal in are very complex.  As a whole, farmers today are achieving higher yields than ever before in our history.  That means we’re also taking more nutrients out of the soil in order to achieve these yields.  Therefore, we have to use commercial fertilizers to replenish the soil.  But with that, comes great responsibility.  Responsibility to apply the right amount of nutrients, at the right times, to maximize efficiency but also minimize negative results such as run off.

I look forward to sharing much more on how we are utilizing technology on our farm to improve our practices.  Thanks for reading!