Reachout: Irrigation, When does it start?

By Mike Zwingman

By Mike Zwingman

Last week, I promised a return this week to my series on soil health, but I want to delay that return just a bit longer because today I’m feeling a little anarchical.  Today, I want to bring a little anarchy to agronomy, to challenge the conventional wisdom that will otherwise bring rootless and floppy corn to your fields this July.

This is our topic today: Irrigate in May.

I hear your collective groan.

I know the irritation of irrigation—the twice daily trips to the pivots, the oiling and the fuel, the constant babysitting of machinery with no predictable end.  To irrigate early is to lengthen such drudgery.

But maybe not.

What if I told you that irrigation in May might save you irrigation in June and July?  That it might save you from headache in September, when your combine can cut through corn standing straight and tall?

Conventional wisdom tells us this: that denying your corn plants water when they are small forces them to seek it out and socket their roots down deep.  This is the wisdom that guided your grandfather, your father and your mother as they authored a dry May for their fields.  But we live in a new age, and new, cutting edge information allows us to make new, cutting edge decisions.

UFC Reachout 4.29.13Because the thing is; roots don’t grow down seeking water.  Roots grow down due to gravity (the “gravitrophic response”) as long as the porosity, temperature, and moisture of your soil allow them.

Contrary to conventional wisdom, moisture in your soil in May will lead to deeper roots.  A shallow irrigation in May is essentially positive reinforcement for your plants to root deep and strong; it is a way to train roots to grown down.  Which means that you’ll enjoy heartier, healthier plants, higher yields, and a less stressful harvest.

When the soil that surrounds the roots of your seedlings is overly dry and hot, nodal root development is discouraged—nodal roots either fail to develop or they grow shallow and knotted, which robs your plant of not only water and nutrients, but also the structure that anchors it firmly to the ground.  Sometimes, it is our own doing that puts our seedlings in overly hot and dry soil: we run our planters too fast or plant in soil that is too wet (which causes problems with sidewall compaction and with closing the seed trench).  Other times, we have absolutely no control over the reasons that our seedlings are struggling in hot and dry soil: a hard rain after planting compresses the soil or washes it away or the wind blows hot and strong, zapping the moisture from our fields.  You have only to think about last May to understand the havoc and pain that the weather can cause.

RUFC Reachout 4.29.132egardless of the reason that your seedlings are toiling in unwelcoming soil though, a little water will alleviate some of their suffering.  A shallow soaking early on can mitigate the issues of a problem planting no matter the cause and will certainly address most challenges that the Anemoi throw our way (those are the Greek gods of wind, by the way).

Which leads me to my next point: Everyone can benefit from early and unconventional irrigation.   But rather than take my word for it, go scout your field in late May to take a look for yourself.  Keep an eye out for plants that are pale and off-color, not quite the gorgeous green that you expect from a corn plant.  Dig one up and take a look at its roots: Are they spindly or knotted?  Is the surrounding soil markedly dry?  Then you, my friend, are my target audience.  Turn on the pivots.

Still reluctant to charge the pivots so soon after parking the planter?  Read on, lest you think me a lone wolf.  It seems that everyone is talking about rootless corn syndrome, from scientists at Purdue to scholars at our very own UNL.  Google it and you’ll have a week’s worth of good reading, I promise.