When I am asked a direct question from a farmer or a crop consultant my response is always as follows.
“Do you want the short answer or the long answer as I can say the same thing in five minutes or five hours?”
Their response to me is almost always the same.
“Just the facts, Jack.”
I will attempt to answer four agronomically important and challenging questions in a succinct manner. However as we all know brevity can be a gift or a curse depending upon the context of the question. With that being said here we go!
Question No. 1 – When should I start planting soybeans?
My general response is to start planting your soybean crop about seven to 10 days before you start putting your corn in the ground – with the caveat that the soil is fit and you are following your crop-insurance replant dates. Review the updated U.S. Department of Agriculture’s Risk Management Agency map. We’ve measured soybean-yield loss due to delayed-planting date as early as about April 10 in parts of the Midwest. But the rapid yield decline – as much as .5 bushels per acre per day – occurs at about May 10. As you would expect, the magnitude of that planting-date yield response is soil- and climate-dependent. Yield losses in some areas were as much as 2.8 bushels per acre per week for delayed planting.
Question No. 2 – What is the optimal soybean-seeding rate?
The quest for the optimal agronomic soybean-seeding rate for yield vs. the optimal economic seeding rate has been an ongoing debate. Fortunately a large group of academics and industry researchers were able to combine data sets and address the question. Our results suggest that for “on-time” soybean-planting dates the optimal agronomic soybean-seeding rate to achieve 99 percent yield potential ranged from 237,000 to 128,000 seeds per acre – assuming 90 percent germination – across environments. The optimal economic soybean-seeding rate ranged from 157,000 to 103,000 seeds per acre. Thankfully that closely confirms my original recommendation that you buy a bag an acre and place about 20 percent more seed on the worse-yielding acres and about 20 percent less on the excellent-yielding acres, especially in areas of extreme white mold concern. But if planting is delayed we recommend you increase your seeding rate accordingly.
Question No. 3 – When should I apply my pre herbicide?
The effectiveness of pre-emergence herbicides is influenced by many factors including application time, soil type, weather conditions, and weed-seedbank community composition and infestation level. The ideal time to apply a pre-herbicide is shortly before the onset of emergence of the target weed species followed by 1-2 inches of activating rainfall. But that’s often not the reality under field conditions.
For soybeans planted in May, applying a pre-emergence herbicide at or shortly after crop planting is a standard practice and makes agronomic sense. But deciding when to deliver a pre-emergence herbicide to ultra-early-planted soybeans can be challenging. One of the challenges is that some of the effective pre-herbicides for waterhemp control should be applied within three days of soybean planting according to their labels – such as flumioxazin and sulfentrazone. If soybeans are planted in mid-April, and waterhemp doesn’t start emerging until mid- or late-May, should a pre-herbicide still be sprayed in April within three days of planting? Or should a grower decide on a more-flexible chemical program that allows for a later application?
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