Planting corn: How late is too late? K-State agronomists answer questions
For the third year in a row, rainfall and cool weather have delayed corn planting in parts of Kansas. This is of particular concern in southeast, east central, and south central Kansas, where many farmers like to complete corn planting by early- to mid-April, said Kraig Roozeboom, Kansas State University Research and Extension crop production specialist.
There's still plenty of time left to plant corn in Kansas, but where soils are already saturated and more rain is predicted, producers may be asking questions about the issues surrounding later planting, he said. Those questions may include: How late is too late to plant corn? What yields can be expected with later-planted corn? Should different hybrids be used after a certain date? When should I be thinking about switching crops?
It is already past the optimal window for planting corn in far southeast, east central, central, and south central Kansas, especially on shallow, upland soils, said Doug Shoup, K-State Southeast Area Extension crops and soils specialist.
"We usually recommend that upland soils in southeast Kansas be planted by April 15 to 20. River-bottom soils, with a deeper profile and greater water-holding capacity can be planted through the first week or two of May with a relatively high probability of success," Shoup said.
There is more time remaining to plant corn in other regions of Kansas, Roozeboom said. The likelihood of a freeze occurring before corn reaches physiological maturity is relatively low unless corn is planted very late in north central, northwest, or west central Kansas.
The effect of late planting on yields is a bigger concern than the possibility of early freeze damage. For most of Kansas, corn yield reductions will not be significant unless planting is delayed until mid-May or later, he said.
"Be prepared for a 10 to 50 percent yield reduction if planting gets much later than that, depending on the location and growing season. Greater yield reductions usually occur the longer planting is delayed, but every year is different," the agronomist said.
At what point should growers consider changing hybrids?
"Unless planting is delayed until late May or early June, most growers should probably stick with the hybrids they typically grow. Switch to an earlier-maturing hybrid only if you are concerned about running out of growing season in the fall. That is typically a greater problem in north central, northwest, and west central Kansas than in the rest of the state," Roozeboom said.
At what point should producers who were planning on planting corn switch to planting a different crop instead?
"Right now we are a long way from needing to switch crops in most of Kansas. However, if planting is delayed until mid- to late-June, be prepared to switch to a crop that can mature in a shorter growing season," Roozeboom said.
Later-planted alternatives to corn include sorghum, several different summer annual forages, soybean, cotton, and sunflower, he said.
"Be aware of possible rotational restrictions due to herbicide carryover and determine how best to utilize pre-applied fertilizer. There may be crop insurance implications as well, so be sure to clear late planting and crop changes with your crop insurance representative," he added.
More information is available in the K-State Research and Extension publication C-560 "Corn Production Handbook" at county and district Extension offices and on the Web at http://www.oznet.ksu.edu/library/crpsl2/samplers/c560.asp. Kraig Roozeboom can be contacted at 785-532-3781 or firstname.lastname@example.org.