High Yields? Don’t Let that Become a Drain on Soil Fertility

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Expert advises farmers maintain fertilizer plans regardless of yield

So you had a high soybean yield this year, and now you’re worried that your crop is removing more nutrients from the soil. There’s good news for you: You don’t have to panic.

“It’s an important concern, and farmers should recognize that high yields remove more fertilizer than normal,” says Dave Mengel, Ph.D., professor of agronomy at Kansas State University. “But even in the case of a really good soybean crop, we don’t experience the drastic changes that some would envision.”

A primary concern of soybean farmers is the removal of phosphorus from the soil.

“Removing a significant amount of phosphorus doesn’t have a large effect on the soil test,” assures Mengel.

While that phosphorus does have to be replenished, it doesn’t need to be replenished immediately.

“That replacement value doesn’t need to increase nearly as much as we may think,” he says.

Stick with your plan

If you’re one of the many farmers who fertilizes every other year, don’t change now.

“If you have a high yield, but you’re on a non-fertilization year, don’t deviate from that schedule,” says Mengel. “The soil will draw from its reservoir in the short-term.”

It’s when every other year turns into every four or more years that you may start to see a drop.

Mengel advises farmers to keep soil-test records and watch trend lines.

“If your yields go up but you don’t adjust your fertilizer recommendations, your trend will go down,” says Mengel. “I recommend keeping soil tests in the manageable zone where you don’t have to worry about high-yield years.”

Invest in the test

The last thing many farmers want to do is spend more money, but Mengel advises that soil tests should be considered part of a long-term quest to improve soil quality.

“Take advantage of the fall and winter months to test your soil and really study your nutrient levels,” recommends Mengel. “Then you can account for variability across the field and apply fertilizer efficiently and economically.”

While the concept of soil testing isn’t exactly a new one, there have been impressive modifications.

“It’s not the same old story; it’s an improved story,” says Mengel. “And I will never stop promoting the importance of soil testing.”