Nutrient Management Trends

Aligned around the 4 R’s, new practices can improve your bottom line and the environment.

Along with raising corn and soybeans, Brian Herbst operates a contract hog-finishing enterprise on his farm near Kasson, Minn. Because he annually applies the resulting manure on his fields to supplement crop nutrient needs, he’s used to doing plenty of nutrient management planning and regulatory paperwork. He’s well aware some of those nutrients could stray into local creeks and rivers, so he manages residue, knifing in slurry to precise depths and then tracking movement of nitrogen and phosphorus in his fields. And he volunteered to be part of the Discovery Farms Minnesota program, a farmer-led effort to gather field-scale water quality information from farming systems across the state.

While some farmers fear such scrutiny, Herbst says he welcomes the help. “I want to know if I’m losing nutrients and if there are ways I could improve our management plan.”

After two years of monitoring, water and soil analyses have been encouraging, he says. “So far there haven’t been any red flags. That’s reassuring.”

The monitoring has also helped him focus crop nutrient management, fine-tuning soil sampling and fertilizer applications to align them with the 4 R’s of nutrient stewardship — choosing the right nutrient source to apply at the right rate in the right place at the right time.

Such tenets are driving grower and retailer practices around the country, as evidenced by the following 10 nutrient management trends.

Both growers and retailers have invested in variable-rate (VR) application technology, with the number of dealers offering VR fertilizer application doubling over the past five years, says Troy Greenfield, manager of crop protection, seed and CHS YieldPoint® services.

“These technologies are being used at planting and throughout the growing season to customize what’s happening on every field pass,” he says. “With services such as CHS YieldPoint, we’re able to layer grid soil sampling, land slope and in-season crop imagery with historical field data to create application prescriptions tailored to each field’s yield potential.”

VR application is now being used for nearly all fertilizer and soil amendments, says Paul A. Trcka, agronomist and YieldPoint specialist at the CHS Rochester location at Grand Meadow, Minn. “Nearly all lime applications and around 90 percent of fall potash and phosphate applications made for our customers used VR technology.”

Concerns about the impact of nitrogen runoff on water quality and input costs are prompting a move away from fall-applied nitrogen (N) in some parts of the country. “We’re seeing a gradual shift here in southeastern Minnesota,” says Trcka. “Fall application is a convenient option for easing the busy spring workload for many growers, but more are viewing it as an economic gamble to apply nitrogen six to eight months before it’s needed. Studies show that in our area, the greatest potential for nitrogen runoff is in March and April, due to snow melt.”

Over the past decade, Trcka has helped Herbst switch to spring-applied nitrogen fertilizer for that very reason. “Cropping economics is a main driver, but taking care of the environment is also important. I want to be able to pass on healthy soils and clean water to my three sons.”

An effective strategy for having nitrogen in the right place at the right time for maximum plant uptake is making multiple spring applications, says Greenfield. “By spoon-feeding the young crop, you’re better able to control the fate of the nitrogen, minimizing the chance that a big rain would push it too deep in the soil or that it could be lost through denitrification into the atmosphere.”

Split spring nitrogen applications are quickly becoming the norm, with planter-applied and side-dress timing gaining in popularity, he notes. “Equipment manufacturers and the aftermarket industry have responded with new fertilizer delivery systems.”

The convenience of in-furrow application appeals to many growers, and it’s an effective delivery method for starter fertilizers, says Troy Jenkins, agronomist at North Central Cooperative, Wabash, Ind.

“It’s effective, efficient and easy to set up. Many growers have been outfitting new planters or retrofitting existing ones for in-furrow starter fertilizer application, as opposed to applying starter fertilizer 2x2. It allows hauling smaller fertilizer volumes and covering acres more quickly. In our northern Indiana trade area, I estimate nearly 25 percent of corn acres were planted that way last season,” Jenkins says.

It’s easy to add fungicide, insecticide, micronutrients and biologicals to make an all-in-one starter application placed right next to the seed, adds Greenfield. “When it comes to important early seedling growth, it’s not about what you apply to the soil, but what you get to the plant that counts.”

Starter fertilizers use has been growing in popularity because it provides just the right amount of nutrients where seedling roots grow. Research shows that more root growth and bigger root systems usually produce taller plants with thicker stalks and bigger leaves, says Maria Abbott, agronomist and product manager for CHS Agronomy.

“In field trials, plants treated with CHS XLR-rate® liquid starter fertilizer (7-23-5) had healthier, stronger appearance at the V5 to V6 stages and more abundant root systems than plants that received no starter,” Abbott says. “We tend to see the biggest benefits from starter fertilizers in cold, wet springs, during early or late planting, when soil phosphorus levels are low and when plants suffer from significant stress, such as heat or drought stress. Healthier young plants are better able to handle adverse conditions.”

Meeting the nitrogen needs of rapidly growing corn can be a challenge. At the V10 to V11 stages, corn plants can require as much as 5 pounds of N per acre per day, says Jenkins. “The key is to supply enough to take the crop to tassel stage.”

To allow for late-season applications, high-clearance sprayers provide a good solution. Herbst applies his own crop protection products and last year fitted his self-propelled sprayer with risers and drop tubes to deliver a final nitrogen solution and ammonium thiosulfate application at around the V10 stage. “About half of the UAN will be available to the plant right away and the other half will become available within two to three weeks, which should carry the crop through,” he says.

Supplying a corn plant with small amounts of nitrogen more often in the growing season improves efficiency, notes Jenkins. “A grower who applies anhydrous ammonia preplant with no stabilizer in the spring might need 1.2 pounds of N to produce each bushel of corn. But with more intensive management, including several well-timed nitrogen applications, a grower should be able to push that ratio to 0.8 pounds of N per bushel.”

To help customers achieve that efficiency, Jenkins has developed the N Solutions program, which North Central Cooperative will launch this spring. It will include several in-season soil and plant tissue tests (V5 to V6 and V12) and soil testing at the dent stage. “The goal is to track crop N use throughout the season so we can maximize N use efficiency and minimize environmental exposure,” he says. “Most growers in our area are concerned about the nitrogen effect on the Gulf of Mexico, so this has become a very important tool.”

Other important tools for reducing nutrient loss are nitrogen stabilizers and inhibitors, says Jenkins. “Some growers need to re-educate themselves on the older products and learn about new ones because they definitely have a role in today’s N management plans.”

Because up to 30 percent of the nitrogen content of ammonium-based fertilizer can be lost through volatilization in a wet spring, using a product such as N-Edge® nitrogen stabilizer from CHS Agronomy can buy extra time, says Abbott. “N-Edge can be used to treat urea-based fertilizers, including granular urea and UAN, as well as manure, and will provide up to three additional weeks for rain or mechanical incorporation to move the nitrogen into the soil. That offers some insurance against less-than-ideal field and weather conditions.”

Paying greater attention to micronutrient levels has become more important in promoting overall crop health, says Greenfield. “We’re definitely seeing greater supplementation of zinc in corn, along with manganese and copper. Some of these nutrients can be conveniently delivered through a starter fertilizer, but don’t just assume more is better. Be sure to review soil analyses with your agronomist to make sure the needs of your specific fields and crops are being met.”

Reduced sulfur emissions from industries and vehicles have improved air quality in recent decades, but also have led to sulfur deficiencies in many soils. Factoring that need into season-long nutrient recommendations has become important, says Jenkins. “Some even call sulfur the new macronutrient because of its importance in several key plant processes, including photosynthesis, nitrogen absorption and nodule formation in legumes.”

This sulfur need has led to increased demand for ammonium sulfate and ammonium thiosulfate, especially where soils are lower in organic matter, such as northern Indiana, northern Ohio and southern Michigan.

A wealth of information and tools are available to help growers manage crop nutrients, says Trcka. “Services like YieldPoint really put the grower in the driver’s seat, and should make him feel more confident in his agronomic decisions.”

Since buying his first yield monitor in 1995, Tom Connors has been fine-tuning field data to make his 2,500-acre corn and soybean farm more efficient, profitable and environmentally responsible. Regularly upgrading his technology and working closely with local agronomy manager Regan Wear at CHS Shipman to revise his agronomic strategies allows Connors to micromanage every acre of his fourth-generation Shipman, Ill., operation called Triple T Farms.

The farmer-agronomist team was one of five pairs named 4R Grower Advocates for 2016 by The Fertilizer Institute. The award recognizes growers and retailers who are dedicated to implementing the 4 R’s of nutrient stewardship — using the right nutrient source at the right rate, the right time and in the right place.

For nearly two decades, Connors has been grid-sampling soils and using variable-rate (VR) technologies to apply crop nutrients. The first year of VR application was rather crude, he recalls. “I sat next to the driver, on an upside-down bucket in the cab of the co-op’s fertilizer spreader, using field data on my laptop to tell him when to adjust the rates. We’ve certainly come a long way since then.”

Now Connors and Wear use CHS YieldPoint® to create management zones within each field, based on cropping history, soil type and yield potential. “Based on yield goals, we write customized crop nutrient prescriptions, as well as VR seeding plans, for each zone,” explains Wear. “The Connorses have the benefit of many years of good field data. The YieldPoint system gives us the power to analyze all that data and make sound management decisions. That’s what the 4 R’s concept is all about.”