A vertical tillage tool hooked to a tractor shouldn't be sitting in a field that's already planted – not if the corn is coming up. I spied it a few days ago in a field that was planted in early May. Before long it was reworking the field. A planter arrived and planted well into the night.
While soil temperatures warmed up after the first planting, cool weather set in – the field took several heavy rains, and didn't apparently recover to the farmer's satisfaction. The soils crust easily. He replanted the entire field.
From what we've heard, that's not likely the only field that's been replanted. It seems to be a matter of who got which hard rain, or who got a shower to soften up a crusted field, and who didn't. Overall, many fields planted in early May are greening up and taking on the appearance you would expect during the first week of June.
Replanting now becomes dicey from an economic standpoint. The Purdue University Corn and Soybean Field Guide shows sharp yield penalties for delay into June for Corn, which would simulate replanting, and that's assuming you can get a good stand the second time.
Some farmers have also been worried about soybean emergence, even in no-till fields. Apparently in some cases beans were just cracking through, with the hypocotyl pulling up the cotyledons, when one of those last cool nights may have caused some injury.
From past experiments soybeans tend to be more resilient to cool temperatures than corn. However, it can depend on the length of the cool spell, the actual temperature, and when it occurs during the growth stage.
Soybeans can withstand 24 to 26 degrees if they are emerged for two to four hours with minimal loss, based on past tests at Purdue University and other places. However, that's far different than just cracking through the ground.
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