Reduce total nitrogen applied to corn using multiple in-season (sidedress) applications

At ROWBOT, we are driven to increase farmer profitability by reducing input costs and boosting yields. It has become clear to us that a management plan with multiple in-season nitrogen applications is the ticket to using this costly input efficiently. Our goal is to make these in-season nitrogen applications easy and extremely cost effective.

During the 2016 growing season we carried out two nitrogen strip trials in collaboration with Shannon Gomes (Cedar Basin Crop Consulting), who connected us with a couple of progressive growers in NE Iowa.

 Description of the three nitrogen treatments, with in-season applications in mid June and early July.

Description of the three nitrogen treatments, with in-season applications in mid June and early July.

For the field data shown here, we had three treatments replicated three times in strips that were about 1200 feet long. We are indebted to Clark McGregor, who took care of the early nitrogen applications and harvested the strips.

Treatment A was the farmer's normal treatment--most of the nitrogen was applied during mid June. We added a second in-season nitrogen application for treatments B and C. Based on the Adapt-N model, the recommended application for B and C on July 1st was about 35 lb N/acre. We decided to have the B treatment at 60 lbs/acre and the C treatment a bit lower than the Adapt-N recommendation at 30 lb N/acre.

 This is how the total nitrogen in each treatment stacked up. The "Reference" is included to show how much the grower would have applied if all of the nitrogen were applied at or before the time of planting.

This is how the total nitrogen in each treatment stacked up. The "Reference" is included to show how much the grower would have applied if all of the nitrogen were applied at or before the time of planting.

The harvest data are in, and the results are quite impressive! Even with 15 lb N/acre less in treatment B, the measured yield was slightly higher than the control--treatment A (statistically, there's not a difference between the yield of treatments A and B given we have just one set of strip trials). Surprisingly, treatment C that had a whopping 45 lb N/acre less than the control had only a slightly lower yield (the difference is only marginally significant).

 Yield data from the three nitrogen treatments. Grain from each strip was measured in a weigh wagon and moisture estimated from the combine's yield monitor.

Yield data from the three nitrogen treatments. Grain from each strip was measured in a weigh wagon and moisture estimated from the combine's yield monitor.

The addition of a second in-season nitrogen application meant that we gained about two weeks of additional insight into the season before the final nitrogen application was needed. Plus, not all of our nitrogen was on the field during late June, which was a fairly wet period (see comparison to other seasons below).

We are making plans for an expanded set of field trials for the 2017 growing season that should further underscore the value growers can realize through multiple, in-season nitrogen applications using the ROWBOT platform.