For the last two years, in two separate locations, a study has been conducted to determine how early soybeans can be planted in Ohio. In the past, studies have looked at early planting at the end of April or early May. Dr. Laura Lindsey, OSU Extension State Small Grains and Soybean Specialist, is looking at an earlier planting date than the past, and also the interaction between very early planting and the presence of cover crops. “The past two years we were able to plant soybeans for this project in Wayne County during the first week of April, and last year in Clark County we were able to plant the soybeans on March 30th,” said Lindsey. “We really wanted to see how early we can plant soybeans. Almost every agronomist will tell you that it is important to plant soybeans early.”The other aspect of this research project is the interaction of planting early, and cover crops being in the rotation ahead of the soybeans.
“In Wayne County there was an interaction in the very early planting (first week of April) with the cover crops," Lindsey says. "In the early planting with no cover crops, there was a lower than desired stand of about 80,000 plants per acre. In the early planting with a rye cover crop, the stand was even lower at around 20,000 plants per acre. There was a negative interaction with the very early planting date and cover crop. When the soybeans were planted at a more normal planting date, the presence or absence of a cover crop had no influence on the stand. For the very early planting date, especially with the cover crop, we observed a reduction in stand, and also in the final yield by 20-30 bushels per acre.”
There are multiple possibilities as to why the negative interaction between the cover crop and soybean stand occurred in the very early planting.“Asking why the negative interaction occurred is a really good question, and one we want to do more research into,” Lindsey says. “When looking at the reduced stand with the very early planting date and cover crops present in Wayne County, there seemed to be more than one problem. There was slug damage and some bean leaf beetle feeding. The cover crop seemed to keep the soil a little cooler and wetter and there were some diseases observed in the crop. There was also some frost damage where the cover crop seemed to trap some of the cold air compared to the bare soil. It did not seem to be just one thing, but multiple. It opens the door for more research to pinpoint what was happening in the interaction between the cover crops and early planting stand.”Dr. Lindsey pointed out that the negative interaction was only observed at the very early planting date (end of March, first of April). There was not a negative interaction between the cover crops and soybean stand with the more normal planting dates. Research will continue into some aspects of this project.
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