19 Feb 20

In the Fall of 2016 was the first time I met Kelly Garrett. I knew he was an innovative minded farmer after our first conversation. I was excited to get know him and his operation further that fall. As we spent time in the combine discussing different aspects of his operation, we had a lot of similar ideas in crop production and how to use technology to more efficient. The last day of corn harvest in 2016, he would throw me a curve-ball in the way he wanted to manage his Variable Rate Nitrogen program.

I have been in the Ag retail business for nearly 15 years and most of that time in the Precision Ag Sector. I was fortunate to spend time with some of the Precision Ag pioneers in my early years. In those early years, I had learned to build your precision ag program based off management zones from the merger of historical yield maps. Once those management zones were built you would have the highest productive zones, average zones and least productive zones of the field. I could then assign an appropriate seeding rates and fertility rates to those specific zones. The standard practice of my education was to place your highest fertility and seeding rates in the most productive zones and scale the rates back in the lesser producing zones within the field.

This means the highest producing zone was getting the highest Nitrogen rate within the field and your lowest-producing area would get the lowest rate. The concept made sense because why put more Nitrogen in your least producing area. In the 20+ years of Precision Ag that’s the way it was accepted.

That last day of the 2016 Harvest, Kelly told me he wanted to do the opposite with his Variable Rate Nitrogen program. “You mean you put the lowest rate of Nitrogen in the highest producing area of the field?” I asked. “Yes, is that wrong?” Kelly replied. The conversation went back and forth on the each other’s concept of Variable Rate Nitrogen. I explained to him my experience of making Variable Rate Nitrogen Maps and how this was completely against the grain. I was highly skeptical and concerned that he was shorting his Nitrogen in the most productive parts of the field. Kelly explained that the high producing parts of the field had higher nitrate levels in the residue and soil because it was the highest producing part of the field. He further explained that because of the higher residual nitrate in those are- as they didn’t need more Nitrogen but less. I was intrigued but also highly skeptical at that same time. I was interested in learning if this theory would hold up because I am an analytical person and use data to prove these types of concepts in the agronomy world.

Since that conversation I have worked with Kelly implementing his idea of Variable Rate Nitro- gen on his operation. Below is a comparison of a field that have the conventional Variable Rate Nitrogen program (Left) and Kelly’s Variable Rate Nitrogen Map (Right). This field is rotated, no-till corn field.

How do we assess that this concept is viable agronomically? When measuring Nitrogen it is important to know how efficient you are in producing a bushel of corn. Yield is important but we want to efficient as we can in growing that bushel of corn and allows me to know if we need to make changes to a grower’s Nitrogen program. Below is the Yield map, N Efficiency map and subsequent report. (Disclaimer—This is only looking at the applied Nitrogen from the Variable Rate prescription and not the total N applied to the field.)


The data from this example proves that Kelly’s Variable Rate Nitrogen program is valid and it is helping him be more efficient with his Nitrogen.

Since working with Kelly on his Variable Rate program, it has helped me be open to different viewpoints of farming. The old adage— “If it ain’t broke, Don’t fix it.” applies a lot in farming today and we like to do what has worked for 20+ years. That’s what I thought with Kelly’s Variable Rate Nitrogen and didn’t think there was something different. His approach was outside the box and challenged me to think differently then before. I think we all get caught up in hitting the easy button in the busyness of every day life. Those excuses can be what hold us back from the next great discovery. I would im- plore everyone to try something new but do it on small scale and do it well. Rethink what you once thought was normal.

Mike Evans