When farmers do get into their fields, Nielsen says 25 percent to 30 percent of the corn crop could be planted in a week and the rest of it a week later - still in time for maximum yield potential.
"So we can catch up pretty fast," he said.
Yield potential typically is greatest in Indiana when corn is planted by May 10, but tillage, soil fertility, and mid-summer rainfall and temperatures are among many other factors that influence yield.
"By itself, delayed planting isn't a sure path to lower yields," Nielsen said.
Farmers in 2009, for example, had planted only 20 percent of the crop by late April because of wet conditions, yet their yield at harvest was 9 percent above trend.
But if farmers can't get into their fields by mid- to late May, they might have to decide whether to plant hybrid seeds other than they originally planned. The switch would be to a hybrid that would take less time to mature so the crop could be harvested before the threat of an autumn killing freeze. The tradeoff for them, however, is that such earlier-maturing seeds might not yield as much grain and, consequently, not as much income.
Detailed information on what farmers would need to consider if they are seriously delayed in planting corn is available at http://www.agry.purdue.edu/ext/corn/news/timeless/HybridMaturityDelayedPlant.html.
Weather conditions in early May aren't crucial for soybeans since many farmers plant their corn ahead of soybeans. Planting of soybeans, therefore, also could be delayed. Soybean farmers usually are at the early stages of planting at this point, with nearly half of the crop planted by May 20. Planting can extend well into June.
Still, eventually soybean farmers, too, will depend on the weather for favorable conditions so they can do their job.
"Just because it's a day in a workweek doesn't mean you can get out in the fields to work," said Shaun Casteel, Purdue Extension soybean specialist. "A person working in an office goes to work rain or shine. Not so for farmers."