May 21, 2008
It is hard to believe, given how wet it has been this spring, but we could use a nice rain to soften the crust on many fields where crops have not yet emerged. According to the National Weather Service, that rain may not arrive soon for many of us. So, do you rotary hoe or not? Rotary hoeing may aid emergence, but it can also cause much damage.
Corn seldom needs help with emergence, but I have been in some fields where the crust is very thick and hard and enough light is getting down through cracks in the soil that the coleoptile (tip of the shoot) is turning green. The green color means that photosynthesis is being conducted and the plant may “think” it is at the surface and the leaves may begin to unfurl under ground. However, if the tips of the coleoptiles are close to the surface, the rotary hoe may cut many of them off, resulting in significant loss of population. And if some plants are already emerged, some of them may also be lost due to rotary hoeing.
Soybeans more often need help getting through a crust. If the seedlings are just below the surface so the arch (neck) is close to the surface, rotary hoeing may break off many of the seedlings, and they will then be lost. If seedlings are still deeper in the soil, rotary hoeing may be a tremendous help.
For both crops, the best way to decide about rotary hoeing is to run the implement for a few yards through the field and then go back and see how much damage is being done to the crop that is trying to emerge and any that has emerged. If little damage is being done to the crop, continue to rotary hoe. If damage is severe, leave the field and see if the plants can make it on their own.
Hopefully the areas where crusting is most severe will soon receive rain to alleviate the crusting problems.
If you have any questions, please feel free to contact the Iowa State University Extension Office.
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