Corn with Preplant N Gets Nod Early

Consider the season a marathon, rather than a sprint.

Published on: Jun 23, 2008
You can't drive the countryside over most of the Midwest without seeing yellowing from wet spots where nitrogen is tied up in saturated soils. This will be a season where how nitrogen was put on, plus the rate, may wind up making a huge difference in corn yields.

Jim Facemire, the Edinburgh, Ind., farmer who tends the Farm Progress Corn illustrated plots. Says that before he sidedressed the sidedress part of the study last week, the corn that had received urea pre-plant was obviously greener. The plots took on more than 17 inches of rain since planting the last week of May.

Due to the late planting date, it appeared the pre-plant N vs. sidedress test might not show much difference this year. Typically, with planting in late April and sidedressing not until late May or early June, expected loss due to wet weather in the pr-plant plots would be expected to show up by the end of the season. But planting so few days before sidedressing was expected, the CI crew wondered if there would be a difference.

That all changed with the record rainfall, termed by the Indiana State Ag Climatologist as a one in one-thousand year rain event in the local area of the plots, fell about 10 days after planting. While this plot didn't flood, soils were saturated. These are typical silt loam soils. They are not underlain by gravel as are some of the soils where the plots are located.

So far the difference is the reverse of expected, with the plots where urea was applied before planting looking better. Expect that to reverse, however, once the rest of the field gets its shot of nitrogen. By the end of the season, one might now expect the sidedress plots to perform better. While the preplant corn looks better now because N is available to the roots, if too much N was lost, it may run out of gas later.

Jim Camberato, Purdue University extension agronomist, commented that if N was applied within a few days of the huge flood in the ammonium from, little loss would be expected if the form was anhydrous ammonia. It typically takes ammonia two weeks to convert to the nitrate form more subject to loss.

With urea, about one-fourth could be expected to already be in the nitrate form. Some of that may have been lost, he suspects, although the exact amount of loss is hard to determine.

Stay tuned to see if the sidedress plots green up once the 170 pounds of N is applied. It's about the same rate applied with urea earlier. These plots follow corn. No starter was applied.