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Along with genetics and fertility, weather is critical in determining how a crop yields. How these three factors interact, overlap and intersect is what farmers try to improve upon in every field they farm, since every advantage they can glean means more grain in their fields and more profit in their pockets.

Managing nutrients is one area that farmers spend time and seemingly ever-increasing amounts of money to tweak to their greatest advantage. The International Plant Nutrition Institute (IPNI) released a best management practice it calls 4R nutrient stewardship. The 4Rs are a reminder to apply nutrients from the right source at the right rate, the right time and the right place. IPNI reminds us that getting practices “right” depends on many key stakeholders and partners, including farmers, crop advisers, scientists and policymakers.

One way farmers can get it right is to pay attention to the weather, says Elwynn Taylor, Iowa State University Extension climatologist and agronomist. “Right” in any of the 4R areas depends on the environmental, economic and social goals of stakeholders, according to IPNI; and Taylor agrees.

“The right time is when the plants need the nutrients. If the plant’s not growing yet, it isn’t needing the nutrient yet, but the farmer does still want to have the nutrient in place when the crop needs it,” Taylor says. “Sometimes that means having it there well before the crop needs it, like placing nitrogen on the soil soon after harvest to have it there for next year. Sometimes farmers can be in an impossible place where they have a very narrow window for application, it’s not wide enough to do it in a timely manner, and they need to do it as early as possible – within limits, of course.”

Joe Bruketta, who farms near Table Grove, Ill., says he wanted to protect his nitrogen (N) from the elements and, yet, be able to apply it in a timely manner.

“Our biggest concern with no-till was losing our 28% out in the sunlight,” Bruketta says. “We just felt like we were losing our product. At first we thought we’d just have to boost up our rate, but that wasn’t working, so we went ahead and tried applying it with NutriSphere-N. The NutriSphere-N was keeping my 28% intact through the growing season.”

NutriSphere-N is a nitrogen management product manufactured by SFP. The product protects against N leaching and volatilization by selectively inhibiting unwanted chemical reactions in the soil. Doing this keeps the nitrogen in the more stable ammonium form longer. NutriSphere-N shields nitrogen on a molecular level, keeping enzymes at bay. That means less volatilization, less leaching and more usable nitrogen to aid in the health and development of the plant. The product can be impregnated onto dry N fertilizer or added to liquid N fertilizer.

Since Bruketta no-tills his land, he was concerned about volatilization because he doesn’t incorporate the urea he’s applying. Volatilization occurs when urease enzymes in the soil convert the urea to free ammonia gas. Research has shown if the conversion occurs in conjunction with warm, sunny days, as much as 20 percent of the nitrogen may volatilize within a week of application. In addition, there is a greater risk of volatilization with no-till systems because they tend to have higher residue, which also can impact conversion to ammonia gas.

One way to apply N as early as possible yet keep it in place is to pay attention to the soil temperatures, Taylor says. He recommends not applying fertilizer in the fall until ground temperatures are below 50°F and will stay below that threshold until spring.

“Generally, organisms in the soil will begin to use the energy from applied N and some of those organisms will have the effect of mineralization and nitrification,” Taylor says. “But that biological process is temperature dependent: If it’s too cold for the organisms to grow, they’ll not use it or use it very slowly. After the soil reaches above 50°F, growth can happen quickly and nitrogen can become more susceptible to leaching. That doesn’t make anybody happy. The farmer isn’t happy because the fertilizer is gone, and everybody’s unhappy that it’s in the ecosystem, where it’s not needed or wanted.”

Taylor notes products are available to stabilize N. Those products can be effective both from an economic and an environmental standpoint for farmers. They also can extend the time before the growth of biological organisms within the soil can use the N by inhibiting unwanted reactions. This gives the crop more time to grow to a size and state where it will use the available N before it is broken down and lost to other environmental factors. Taylor cautions nothing is completely immune to extreme weather, but gaining additional time can be helpful.

“This past spring, there was a lot of crop that was suffering from nitrogen deficiency,” Taylor says. “We had a warm, wet spring; and nitrification happened in a lot of areas. This year was a real example of what can happen. With any nutrient protection, there is a time function to it that weather extremes can overcome. But if the N can be protected for a time while the crop is in the ground and germinating, hopefully it will be available at the right time for the crop.”

Bruketta, who likes to plant in early April, says he applies his N treated with NutriSphere-N to protect his spring applications and give him peace of mind that his N will be where he needs it to be when the crop needs it to grow.

“We went with a stabilizer like NutriSphere-N because with a test plot of it – 80 acres with it, 80 acres without – we could see anywhere from a 10 to 12 bushel differential,” Bruketta says. “That sold us on NutriSphere-N. For the cost of it per acre, we get a ton of return, and I’d say it’s worth the money.”

The 4Rs – right source, right rate, right time and right place – can mean different things to different stakeholders. The key can be to frame the conversation with the intended goals. Bruketta uses NutriSphere-N to ensure he can apply his N at a time when weather conditions allow for it. The use of NutriSphere-N also makes several of his environmental goals possible. He can keep his fertilizer rates at acceptable levels while continuing to reap the benefits of no-tilling because he can still minimize N losses while keeping his conservation tillage plan intact.

Search for Efficiency

When as much as 75 to 95 percent of applied phosphorus (P) can get fixed in the soil, making it unavailable for crop uptake, you start looking for more efficient alternatives. Experimenting to find a better solution was just what Joe Bruketta, who farms near Table Grove, Ill., did.

Nitrogen (N) as well as P is responsible for the energy transfer in plants, so it’s critical to plant growth. P bonds with positively charged mineral ions that naturally occur in the soil, such as iron, aluminum, magnesium and calcium. That bonding process leaves much of the P in a form that is unavailable for plant uptake. Over time, bonds in the soil break down and some of the P will be rendered into a bioavailable state; but, for the most part, what farmers put on in a season can be rendered up to 95% unavailable in the soil. Since plant potential is decided in large part by available nutrients early in the growth cycle, Bruketta was looking for an efficient, effective way to feed his plants.

Bruketta talked with his fertilizer dealer and decided to try AVAIL, a P fertilizer enhancer from SFP. AVAIL is a negatively charged, water-soluble polymer that coats P fertilizer and attracts ions that normally lock P in the soil, leaving it more available for crops to use. The first year Bruketta tried AVAIL, his fertilizer dealer applied it on half of an 80-acre field but wouldn’t tell him which half. He wanted Bruketta to draw his own conclusions.

“Of course, I kept questioning him about it. During the growing season, you could see the different coloration in the corn,” Bruketta says. “In the fall, when we went out there and started shelling it, there was about a 7 to 10 bushel-to-the-acre difference. Now we’re sold on it, and everything gets AVAIL.”

Bruketta says several of his neighbors have started using AVAIL as well after hearing about his experiences with the product. “I told them that we reduced our phosphate level in poundage per acre because of this product,” he says. “We’ve got proof that it’s working. We are all in here for the dollar and you want to save as much as you can, and we’re getting very good results.”

Further Reading This is article is part of a series, you can view Part One: Build an Optimal Nutrient Management Plan by clicking here.

February 2012