By Harold Watters, Ohio State University Extension agronomist
Planting date was the biggie. We had our annual Soybean School at the Conservation Tillage Conference recently. Three of our speakers said that planting date was the most important item that growers could change to improve yield. Plant in April if possible or early May if not.
Last year in this column I noted that Fred Below crop physiologist from the University of Illinois at Commodity Classic said the number one influence on soybean yields is the weather. I do have to agree with that — just look at 2018 and you will see how great this influence is.
Variety selection? From Fred’s list of last year, I think genetics is number two (although he did not put it at the same ranking). In looking over the soybean varieties entered in Ohio’s 2018 Soybean Performance trials (http://www.oardc.ohio-state.edu/soy2018/) — there are big swings. Averaged across two sites from 2018 at central Ohio trials for late maturity the highest yielder is 61.7 bushels per acre and the low is 44.8. That’s a swing of 17 bushels per acre under the same growing conditions or in economic terms — almost $150 swing per acre. And you can get Liberty Link soybean varieties or Xtend to put you in that same top tier.
Sulfur? Shaun Casteel of Purdue University in our Soybean School said that sulfur deficiencies are creeping into Indiana. Typically he can see this with light soils with low organic matter, in crops that grow part of their life cycle when we are not getting a lot of mineralization of S from soils — such as wheat and forages, or in early planted summer annual crops. We do need sulfur to grow both corn and soybeans (and all other crops too), but so far we have seen little evidence of the need to apply in soybeans in Ohio. We are watching crops here for sulfur deficiencies but so far have seen few reasons to apply S. You can watch too by putting a strip of sulfur across your crop fields — just one strip can tell a lot but replicate if you can to prove you need it. And it will change across soil types with changes in organic matter. If you do this, use a sulfate form of the nutrient such as gypsum or ammonium sulfate.
Weed control is a big issue in soybean crop production too. Mark Loux, at the Soybean School, said we need to watch for pigweed problems. Missed weeds will continue to be a problem in succeeding years.