Changing Fertilizer Game

Time to Rethink Anhydrous

Jim Patrico
By  Jim Patrico , Progressive Farmer Senior Editor
Greg Carson moved away from anhydrous to in-season N applications using a Hagie equipped with Y-Drops. (DTN/The Progressive Farmer photo by Mark Tade)

It's been three years since Greg Carson and his father, R.J., said goodbye to anhydrous ammonia on their Marion, Iowa, corn and soybean farm.

For years prior to that, they'd followed the same rituals as many Iowa corn farmers: anhydrous in the fall and then again in the spring, maybe followed by a liquid nitrogen sidedressing. But about seven years ago, the Carsons began shifting to a strictly liquid N program. Now, their 3,000 acres of corn get a liquid N preplant application followed by as many as two more in-season liquid N treatments.


"Anhydrous is a gamble," Greg said. "You never know how much of it you are going to lose [between application and the growing season]. For us, the name of the game now is making sure we put on nitrogen in-season when we know the corn plant will uptake it."

The move away from anhydrous ammonia (NH3) was possible for the Carsons and other corn farmers, in part, because farm-equipment manufacturers have been busy. In the last decade, they have created a host of new in-season nitrogen application tools that promise to be more precise, safer, faster and more efficient than an anhydrous and sidedressing combination. Consider a few examples of preplant and in-season options:

-- AccuShot, a new planter product from Great Plains Manufacturing, can place prescribed amounts of starter fertilizer in-furrow at programmable distances from seed.

-- A new high-clearance dry spreader, New Leader's NL5000 G5 Crop Nutrient Applicator, has swath width control and variable-rate capabilities for precise placement of fertilizer, even in a growing crop.

-- Sensor systems such as GreenSeeker, OptRX and CropSpec analyze crop health, and algorithms generate variable-rate nitrogen applications on the fly. The systems are good to the V14 stage.

-- In-season liquid applications are possible all the way to tassel with tools like 360 Yield Center's Y-Drop and Undercover suspended from a high-clearance sprayer.


At the same time new delivery mechanisms came online, new data-gathering technologies sprang up and began to enhance prescription-farming capabilities. Analytical programs like Encirca and Climate FieldView provide in-season nitrogen recommendations based on rainfall received in a field. Aerial, drone (UAS) and satellite imaging have become extremely sophisticated and also are part of the precision mix.

Suddenly, it's possible to be precise and timely with in-season nitrogen applications.

Environmental concerns also have farmers rethinking anhydrous use. Fall-applied anhydrous is subject to degradation and leeching from fields during winter. It can wind up in creeks and drainage ditches. With recent weather patterns, even spring-applied anhydrous is susceptible to moving off site. Five- to 6-inch rains in the spring have become common in his area, Greg said.

Finally, there is personal safety. Accidents happen. Anhydrous ammonia can freeze tissue and burn skin. It can cause permanent damage to eyes and lungs.


None of this means NH3 is disappearing. The old standby's many strengths include cost. "It's cheap to make, cheap to transport," said Peter Scharf, University of Missouri professor, division of plant sciences.

Anhydrous is very concentrated. It is 82% nitrogen by weight, while urea is 46%, and most liquid formulations are 32%. Since other forms of nitrogen fertilizers are made from NH3, it's unlikely they will ever be as inexpensive for the end user.

Just as important, anhydrous is convenient. Corn Belt farmers typically apply it to fields in the fall after harvest. That sometimes leaves nitrogen ready and waiting for a new crop to be planted even if spring rains prevent timely preplant applications of anhydrous or another form of N.

The ability to work ahead during a slack season is a key reason anhydrous has been part of corn farmers' strategies for generations. It's a kind of insurance that the new crop will get at least a portion of its nitrogen needs.

"Everything I was taught in grad school said that two forms of nitrogen at two timings are most stable," said Scott Nelson, director of the Iowa Soybean Association On-Farm Network.

That's one reason he predicts corn farmers will not abandon anhydrous, even in the face of new technologies. "A grand-scale movement from anhydrous to liquid? I see some of that," Nelson said, adding that most Iowa farmers seem content with anhydrous as their primary source of nitrogen.

Scharf agreed: "I don't see anhydrous going away completely." Instead, he envisions more corn farmers reevaluating their nitrogen programs to add variety. "I see anhydrous as a very solid base option," he continued. But weather and other conditions can mean that, "Sometimes you'd better do something else, too."

Fall anhydrous applications, he pointed out, are suspect in years with extremely wet weather. "If you have a fall application, you have to be watching to see if you need an in-season rescue operation because your risk [of insufficient nitrogen at planting and in-season] is relatively high."


That risk seems to be increasing as weather patterns change. "I now see fall anhydrous as not being very viable in the Corn Belt east of Kansas," Scharf said.

Spring and in-season anhydrous applications also have serious weather and time drawbacks. Pulling an anhydrous bar is a slow operation -- maybe covering an acre in two to three minutes, Scharf estimates. By contrast, a high-clearance spinner with a broad coverage area can treat five to eight times as much ground in the same amount of time. High-clearance sprayers equipped with Y-Drop can apply nitrogen at 9 to 13 mph over a 60-foot-wide area. That is more than an acre per minute.

"A major obstacle with anhydrous is speed," Scharf said. "Spring anhydrous is fine if conditions are right, but if field days are limited, you'd better be ready to change your [fertilizer] plans."

If he were farming, Scharf said, he would put anhydrous on 15 to 20% of his fields in the fall at a full rate. He wouldn't risk much N with that formula, but he would save some spring trips in years without winter loss conditions.

Even spring-applied anhydrous can be lost, Scharf said, which is why he leans toward sidedressing and later in-season applications: "The later you go [with nitrogen], the better your odds are to get it through to the crop."

Besides liquid nitrogen in-season applications, Scharf is enamored of new-technology dry-fertilizer machines. "High-clearance spinners are the way to get a lot of acres done," he said. "In-season N has to be fast in today's world."


The Carsons recently decided to trade their anhydrous "insurance" for another form of insurance, and they bought a Hagie STS 12 equipped with a 60-foot boom with Y-Drop. That combination allows them to wait out wet spring weather to apply in-season nitrogen. (To help offset some of the cost of the sprayer, Greg makes it do triple duty as a herbicide and fungicide applicator using a 120-foot boom. The custom work he does with the sprayer also helps justify the expense.)

In a typical year, the Carsons' corn-on-corn gets three nitrogen applications beginning with 70 units in a preplant herbicide program shortly before planting. They follow with 50 units via Y-Drop at the V8 to V10 stages and finish with 50 to 60 more units via Y-Drop at V14 to pretasseling. For corn following soybeans, they skip the middle application, relying on a nitrogen credit from the previous crop. The Carsons' in-season prescriptions are based on recommendations from Encirca. (Editor's note: DTN provides weather data to DuPont Pioneer for use in its product.)

The Carsons' annual yield goal is 230 bushels per acre, which they achieve with about three-quarter-unit of nitrogen per bushel of corn, not the 1-to-1 ratio that used to be common practice when they relied on anhydrous.

"It's working very well for us," Greg said.

What if the spring is exceptionally wet? If there was so much rain in the spring that the Carsons can't get their preplant down, "At that point," Greg said with a laugh, "nitrogen is going to be the least of our worries, because there isn't going to be any seed corn in the ground."

Of course, a year like that might come.

But the Carsons seem convinced their nitrogen program without anhydrous is on a firm economical, agronomic and environmental footing. "The way we do this saves money and makes more efficient use of N," Greg said. "Either we are going to do this [efficient nitrogen application] on our own, or the government is going to step in and tell us what to do. Besides, it's the right thing to do [for the environment]."

Jim Patrico can be reached at


Jim Patrico