In the past, I have laid out the mathematical formula for yield as being the number of ears multiplied by the number of kernels divided by the number of kernels in a bushel, and that hasn’t changed. I’ve spent a lot of time talking about how the only one that we have the greatest amount of influence on is the number of ears. That leads us to now, where hopefully, we have gone out and done NESP’s for every field and rated them on yield potential. Now we get to the frustrating part.
The rest of the yield equation is, for the most part, out of our control. Your max attainable yield potential is already set, so all that’s left is the GAP. The gap is the difference between max attainable yield and the realized yield if we were to do nothing else right for the rest of the year. So, our job is to capture as many of the GAP bushels we can without breaking the bank. See why this is so frustrating?
The first thing we need to realize is what development stage the plant is in on any given day, and how our decisions and the environment around it influence that developmental stage. Like right now most of our corn is somewhere between the V5-V12 growth stages, but from a developmental standpoint, this corn plant is trying to do a lot of stressful things at once. First, it’s embarking on a period of grand growth in which cells are going to be dividing and expanding rapidly, at the same time it is developing a new root system that is better suited for the water and nutrient demands that are going to start ramping exponentially in the next few weeks. Yet while all this is going on, that same plant is trying to develop the number of kernels around and kernels long. Luckily for us, this is driven mostly by genetics, but that doesn’t mean that external stresses will affect development. Things like high heat and winds with hot and dry soils inhibiting nodal root development, or hail and wind damage all will have some impact on kernel development so we need to do our best to react to those stresses when we can.
When we get to grain fill, the risk of potential loss increases exponentially, periods of water and nutrient stresses will cause tip back and reduced test weights. Mitigating those losses are all about managing nitrogen, water, and sunlight. In some cases, we can manage two out of the three, in other cases we only have limited ability to manage one out of the three. If you irrigate we have options, but if you don’t we only have timing on Nitrogen to make sure we get to where we want to go. From an external influence standpoint, anything that inhibits sunlight capture whether it be hail, disease, insect damage will have an impact on final yield.
All this means is we have challenging decisions to make on where to best spend money to mitigate any potential yield losses. The thing is we are constantly reevaluating what our realistic yield goals are, and if we can do that we can make better decisions. Maybe you will have fields that we need to reduce some stress early and make an irrigation pass to kick start some root growth, or maybe we will need to make a fungicide application to ward off diseases. Accepting the fact that we can no longer create yield but only protect it from here on out can be a tough pill to swallow. But it also puts us in a mode to understand what is going on and what decisions make the most sense. Take some time and talk to your FSA about your situation and learn how response scores influence how genetics and environment will collide and what options you have.