AMES, Iowa – The 2014 growing season, at least in central Iowa was, in a word, abnormal.
In a few more words, 2014 saw “very late planting; very cool, early soil temperatures; excess rain,” according to Iowa State University Extension field agronomist Mark Johnson. He covers central Iowa, and says the good news was a low prevalence of insect or disease pressure.
“The two exceptions,” notes Johnson, “were that in some cases, we did see a lot of sudden death syndrome (SDS) in soybeans. The good news was that in most cases it didn’t affect yield a lot, but we probably saw it more widespread than we’ve seen in probably six or eight years. In the corn, we saw northern corn leaf blight, whcih again is not typically a big isuse, we just see that occasionally, and again that was kind of two-pronged; onlots of acres it turned out not to be a big deal, but some acres got hit pretty hard.”
2014 was of course a wet year, and Johnson says oxygen is just as important for root systems as for humans. If pore space in the soil is full of water, as it was after significant rainfall events in the late spring, he says that’s bad news for the plant.
“The pore space normally should be half full of water and half full of air,” Johnson explains, “and when you’re full of water, you squeeze the air out, and when you squeeze the air out, the roots are not getting the oxygen, and oxygen is just as critical for those roots as it is for you and I. Basically, they were gasping for air all summer.”
On that front, Johnson says there is a lesson to be learned from the excess rain: more tillage than is necessary will damage the soil structure, which is responsible for adequate pore space.
“Let’s not do any more tillage than we have to,” Johnson says, “because tillage destroys structure, and structure is what gives you pore space; nice, big pore space. If you do the tillage at the wrong time, not only are you destroying structure in general, but now you’re compressing, and compacting; making those pore spaces much smaller, which lets it hold the water, and keep the air out. So, as time goes forward, I think more and more people are learning to do less and less tillage.”
Johnson says some growers he’s talked to indicated they planned on switching corn hybrids based on moisture levels in harvested grain. Johnson says that doesn’t quite match up with the evidence.
“We had much lower heat unit accumulation,” Johnson observes, “which means that it did finally reach black layer, at a much later time. You don’t start drydown until it hits black layer. So once it hits black layer, we go into drydown phase. We’re late; air temperature is much cooler, and you have much less drying weather. So don’t blame the hybrid that it didn’t dry down: how could it dry down when there’s really no drying weather?”
To hear more about the 2014 growing season from ISU Extension Field Agronomist Mark Johnson, click the audio player above this story.
