The Third Foot

ReachOut: The Third Foot from Central Valley Ag on Vimeo.

by Mike Zwingman

by Mike Zwingman

Is a myth anymore, I am convinced.

We used to talk about it all the time—corn roots reaching over two feet deep—and strive for it.  But I’ve seen the outcome of a lot of striving, and I’ll tell you, that third foot is just never reached.

Take note that it’s not that it can’t be reached.

There’s a lot going into this, I think.  Changes in hybrid characteristics, plant populations, and planting date have all affected root development in our corn crops.  Many hybrids have a fibrous rather than penetrating root system, which isn’t necessarily intentional but is the result of breeding for other very desirable characteristics.  We also once thought that regardless of the type of root system a plant had, planting closer together would drive root development down instead of out.  In actuality, planting closer together makes root systems shallower as in root architecture, depth is determined in a way by diameter and planting close together limits diameter.  Lastly, as planting dates seem to get earlier and earlier, seeds root into colder soil for longer, which can stunt root growth.

Thus the third foot has become mythical.

This is a problem though.  And it’s actually a pretty big deal.  Our plants need roots, people!  They need a big, healthy, awesome root system to help them eat and drink and grow big and tall.  So if we want big and tall plants (that also stand their ground through harvest) we have to make root development happen.

What I actually want you to think about today is how you use your probe and your planter and how these affect root development in your corn plants.  Secondarily (but still of great importance) I want you to understand that root development is not only necessary for big, nice corn plants, but is vital to increasing your efficiency in your Nitrogen and irrigation programs.


I probably don’t need to explicate the problems with a smaller root system.  Since roots are how your plants take in nutrients and water from the soil, a smaller system directly affects a plants ability to do these things.  A smaller root system hinders your plant’s growth and diminishes your efficiency, no matter how well you manage the four Rs.

So what’s a grower to do?  Fortunately, there are actions you can take to support the maximum development of your plants’ roots, and it starts at the beginning: planting.  The best thing that you can do to support root development is to set up and use your planter correctly so that it achieves optimum planting depth, singualtion, downforce, and moves residue effectively.

Having your seed meter tested pays off within the first two acres you plant.  That’s how significant your planter is to your yield.  Even a big job like adding a new hydraulic downforce pays off in 500 acres.

Perhaps that strikes some of you as a big number, but it isn’t alarmist of me to remind you that a bad planting job can’t be fixed down the road.  You lie in the bed you make when you plant, so getting it right is more important than I can impress upon you with mere words!

Once roots are given a good start via excellent planting practices, your probe comes into play.  Using your probe to track root development will help you manage your irrigation and Nitrogen programs to best suit the actual situation of your plants’ roots.

The goal isn’t to save the third foot from mythical status.  Like I said, hybrids and practices have changed.  The goal is to achieve the most root development possible, however wide or deep.  If you’re irrigating for that third foot with a root system that isn’t designed to get there, you’re wasting water.  (This would be a good time to put that probe into play and let it direct your irrigation practices.)  The goal is efficiency.  The goal, my friends, is big, bad corn plants.