Manage nutrients for peak profit

Fertility is often on the chopping block when farmers try to scrape together the last bit of profit from a crop. Lucas Haag, assistant professor of agronomy and northwest area agronomist at the Northwest Research-Extension Center in Colby, Kansas, said hold off before considering cutting this aspect of the budget.

“I’ve had a few people tell me, I’m going to cut fertility. Cut fertilizer 20 percent across the board to make the budgets,” Haag said. “I’m not sure that’s the best way to manage.”

Long-term, producers are having to make these kinds of decisions on whether to choose input costs over making money.

“Where’s the trade-off between the input we’re purchasing and that crop we’re growing,” Haag said. “Because we’re talking about things that have diminishing return. We can keep increasing nitrogen rate and eventually the cost of that next pound of nitrogen is more than that increasing grain yield.”

The threshold for all of this has a lot to do with the cost of nitrogen and the grain value. Haag said for sorghum to be profitable and for fertility to be realized, producers must understand a few things. Yield potential from planting to mid-bloom can change a bunch. There’s “huge swings in potential.”

“We’ve seen tremendous benefit especially in recent years to being able to put on some nitrogen late season in corn,” Haag said. “There’s no reason not to believe we can capture similar benefits in sorghum.”

By listening to what the sensor tells the producer to do can make a difference in yield. Fertilizer does too. As more sorghum moves into irrigated and limited irrigation acres, there’s a huge opportunity with fertigation.

“(They’re) able to come back with a very cheap application cost and time some nitrogen later on in the season,” he said.

With nitrogen, there’s potential for losses. Haag said if farmers are putting urea on in April, May or June, conditions can be conducive to volatilization losses. He’s not fond of the top dress products though.

“But if you’re telling me you’re going out and spreading some dry urea ahead of your sorghum and it’s the middle of May, I’m thinking this is a pretty good investment,” he said.

That’ll give the farmer about 14 days before the volatilization process starts.

In the environment of western Kansas, losses are usually less.

Don’t forget phosphorus, he added.

“I think it’s good to do some back of the envelope math and look at what we’re removing from the field versus what we’re putting on,” he said. “If we’re removing more than we’re applying, what are we doing to the soil test levels? We’re dropping them.”

A good rule of thumb on many Kansas soils is 18 pounds of phosphorus will change soil test 1 part per million. Raising 60-bushel wheat removes 30 pounds of phosphorus.

Starter products are available for sorghum and Haag is seeing some responses to them. There is more of an effect if nitrogen and phosphorus are placed together using a surface dribble.

“Also keep in mind that when we co-apply nitrogen and phosphorus that phosphorus moves down into the soil better when its co-applied with nitrogen,” Haag said. “That nitrogen tends to bring the phosphorus with it down into the soils. We get that added benefit.”

Chloride deficiencies are also something that sorghum producers need to keep on their radar.

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Chloride is mobile and can leach out of the soil and over time farmers have to replace it. Haag said growers often see a yield response to 10 pounds of chloride.

Kylene Scott can be reached at 620-227-1804 or [email protected].