Farm Fresh: How Merging Soil Test Results with Yield Data is Changing Farming

A couple of years ago, we talked about all the data we were generating on our farm, thanks to one-acre soil test grids on over 2,000 acres of our farm, along with yield monitoring data on most of our acres. Recently, we decided to merge these two massive pieces of data to improve our yields.

For years, farmers have gotten soil fertility recommendations from their local fertilizer dealers or maybe their local agronomist, but most farmers have questioned whether the advice was sound.  By comparing soil test information to yield, farmers no longer have to wonder whether or not their fertilizer purchases are worthwhile. They have concrete evidence right from their farms using their data to see whether or not higher levels of fertilizer pay.

One of our favorite things to talk about over the last decade has been how most farmers don’t have nearly enough potassium in their soils. Potassium is key to stalk and stem thickness and durability and a big component of yield. When I have data showing the higher my potassium levels the greater my yields, I don’t have to be a fertility expert to see that I need to get my potassium up if I want better crops.

We put together graphs for each nutrient we measure in our soil tests and compared yield to soil pH and many other factors. We even look at ratios and often say, “balanced fertility is just as important as having ample fertility.” The evidence came from 2018 and 2019 when, in 2018, more copper led to higher yields. We then put more copper out there, but in 2019, our data said the exact opposite—less copper led to higher yields. This was initially a conundrum. What it came down to was our ratio of phosphorus to copper. We had cut back on our phosphorus applications due to the wet fall in 2018, so our soil levels in 2019 were lower than normal. We learned where the phosphorus to copper ratio needed to be and then corrected for 2020.

As simple as this makes fertility recommendations, you may be wondering if every farmer is picking up on this and comparing yield to soil test data. Unfortunately, no. We remain one of the only farms in the United States currently doing this, but we hope to show the value of creating an ideal fertility plan. Today, we have a simple computer program to compare our data.

As farmers continue to accumulate more data off their farms, they will improve yields, lower costs per bushel and be more efficient with all their resources. Comparing yields to soil test data is one of those steps. It has been an absolute game-changer on our farm, and it will be on countless farms in the next few years.




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