When I visited Bob Nielsen and Jim Camberato playing with their souped-up Hi-Boy buggy, trying to gather information on N content within plants, I also got a lesson on the effects of crop residue, at least in one given year. The pair of Purdue Unviersity Extension agronomists were working at the SEPAC farm near Butlerville in Jennings County. The no-till corn was planted relatively early on rolling land.
"The corn up here on this hill is actually taller than we like to run with this sensing machine," Camberato told me. However, since it was built with a huge range of flexibility, Nielsen, driving the rig, could still raise the front boom high enough to get the two types of sensors they're comparing above the canopy.
Looking down between the rows, on the ground, it was obvious this corn was planted into soybean stubble. Due to earthworm activity, the stubble was slightly bunched here and there. "Believe it or not, the mittens are high enough for me to feel them as little bumps when I drive this rig over them," Nielsen quipped. This year's version of the rig doesn't have shock suspension on the booms or for the driver. However, Nielsen intends to ask the master mechanic on the Throckmorton staff who built the rig to see what he can do about that before next season.
A valley runs across the field, between two rather sizable hills. The corn was barely waist high down the slope, into the valley, and up the slope. Checking between the rows, there was a wheat cover, now burnt down. I correctly assume that it was a cover crop, seeded by Don Biehle, SEPAC superintendent, and his crew to help protect the draw against soil erosion.
"Two years ago that was the area where we had the tallest corn," Camberato recalls. "That year it was shorter on the hills at this time of year, and taller in the valley." Recall that two years ago was the summer of '07, brutally dry in June, especially in southeast Indiana where SEPAC is located. By contrast, this season has featured plenty of moisture.
"The cover crop may have held it back by keeping it cooler and wetter under there," Nielsen explains, stopping running his light-metering buggy long enough to let me get a good look at it. "But it may also be an alleopathic effect of planting corn into wheat." Alleaopathy refers to a reaction whereby chemical compounds released by certain dead and decaying plants interfere and slow the growth of other certain plants.
Across the field, I peeked under the corn and saw corn stalks. It was corn after corn, and the next field Nielsen and Camberato were going to measure with their light sensing tools. "It appears to be the most uniform field of the two," Nieslen says,. "It's not as tall as corn here on the ills in bean stubble, but it definitely seems to be uniform."
All it takes is one striking comparison- three residues within walking distance of each other, to prove that what cover and soil conditions you plant into can make a difference, especially in a no-till operation.