Does Starter Fertilizer Become Less Critical Later in Season?

Data from '08 Extension test says 'yes.'

The best laid plans of mice and men…sometimes go astray. Three large tractors have been sitting in a neighbor's barnyard now for nearly a month, implements hooked behind. They look like ferocious hounds chomping at the bit. No doubt the people who would drive them are as well. So far Mother Nature has had other ideas, at least across much of the Corn Belt. Those plans so carefully laid out during the winter- when to plant, how much starter fertilizer to apply, and so forth, now may need adjusting.


There is word that a farmer in northwest Iowa finished planting in late April, and that another no-tiller put plots out in southwest Ohio in late April. But those are the exceptions rather than the rule. One seedsman from an area similar to 'racehorse flats' in central Illinois already figures he'll still be serving customers until early May. And a farmer facing elective surgery in early June is ready to pull the plug, telling the doctor his crops come first.


One plan many make when they anticipate planting early, in cooler soils, is adding starter fertilizer. It's also a staple for no-tillers. In both cases, especially in no-till, agronomists today recommends adding as much or more nitrogen than phosphorus, indicating that much of the yield kick from starter, if there is one, especially in no-till, comes from the shot of nitrogen applied early when conditions are cooler.


Now comes the dilemma. If 'early' turns into May 15 instead of April 15, as originally planned, do you still apply starter fertilizer? What if May 15 becomes June 1? Then what?


Some of the answer may depend upon whether you already have starter fertilizer bought and paid for, and are committed to taking it. But in cases where you're not, what do the agronomics say?


Based on findings in a replicated test at the Purdue University Throckmorton Research Farm near Romney, Ind., last year, Jeff Phillips, Extension educator in Tippecanoe County, Ind., says that applying starter fertilizer at planting late in the season may not pay. If there's a pay back, it may be marginal at best. And it may be tied to other factors, including the population at which you're planting corn.


Due to weather delays a year ago, somewhat like this year, the plots weren't planted until the last week of May. Soils stayed warm after planting. The plots were tilled. When the combine went through the field, there was a slight advantage for starter fertilizer at some populations. But overall, it was negligible. And once he put a pencil to it, it was questionable as to whether the application paid for itself or not.


"It might have been different if we could have planted the last week of April or first week of May," Phillips says. "That's when starter fertilizer traditionally does more good."


Unfortunately, the chance to test that hypothesis by applying starter on plots planted in late April or even early May has already gone by the boards again this year. Even in research, sometimes the best laid plans…are just that- plans. Reality may be something altogether different.

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