Nutrient Stewards

A big part of nutrient management planning is keeping nutrients in their proper places. As important as fertilizer is to a healthy crop and with farmers having an eye on their bottom line, using nutrients effectively and efficiently is one area that draws a lot of scrutiny.

The International Plant Nutrition Institute (IPNI) has introduced 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. Earlier in this series, we addressed some of these factors. But overall, good nutrient stewardship is making sure that nutrients leave the field in the form of crop yield as opposed to being lost to the environment.

Ray McCormick, president of the Indiana Association of Soil and Water Conservation Districts, is serious about nutrient stewardship. McCormick farms near Vincennes, Ind., and uses a combination of cover crops, rotation, conservation plantings and no-till to make sure that he improves his soil quality while managing his nutrients.

“We don’t just no-till, we never-till,” McCormick says. “I believe that cover crops open the door to no-till. By using cover crops, we can build nitrogen levels in our soils by not only preventing our nitrogen from leaving, but by pulling it out of the atmosphere and fixing it into the soil. I plant all fields going into corn with peas to grow nitrogen. It’s one way I can control input costs.”

The extra vegetation also allows McCormick to have something growing on his land almost year-round, helping to keep his soil in place and runoff to a minimum.

“You have to hold onto the soil not only because it’s a farmer’s greatest asset but because the majority of phosphorus that gets into rivers and streams is attached to soil,” McCormick says. “We have seen decreases in the amount of phosphorus getting away because of conservation, but we can no longer keep doing this to the Gulf, the Great Lakes, the Chesapeake Bay; we have to reduce our nutrient loading.”

Phosphorus (P) fertilizer is negatively charged, and, when placed in the soil, bonds with positively charged minerals —iron, calcium, aluminum and magnesium—fixing it in place and making it unavailable for plant uptake. Even if soil P test is high, the amount of soluble P available for plant uptake can be relatively low. Soluble P is replenished from other forms that exist in the soil as it is broken down over time. However, research shows 75 percent to 95 percent of applied P fertilizer is tied up in the soil and unavailable for plant use in the year it is applied. Because the soil bonds with the P, soil erosion is a great source of phosphates showing up in water, McCormick says. He also notes that leaching of nitrogen (N) can happen where farmers aren’t using the right tools to prevent nitrates from dispersing into groundwater.

In addition to conservation techniques like buffer strips and cover crops, newer tools like NutriSphere-N®, a nitrogen management product from SFP, are available. NutriSphere-N 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, which results in less volatilization, less leaching and more usable nitrogen to aid in the health and development of the plant.

“Indiana contributes 10 percent of the nitrogen going into the Gulf, yet we’re looked at as one of the leading conservation states,” McCormick notes.

“If there was an area 7,720 square miles [roughly a quarter of the size of Indiana] that no one could farm for generations due to shrimp farming in the Gulf, we would demand that the government step in. It’s only fair that we make sure that the Gulf is in recovery.”

Steve Moore, who farms near Blakely, Ga., a mere two-hour drive to the Gulf, believes in keeping his nutrients and soil in his field not only because it’s good environmental stewardship but also because it makes great economic sense, as well.

Moore has seen a 25-bushel-per-acre yield increase on average by using AVAIL®, a revolutionary P fertilizer technology also available from SFP that reduces the fixation problem by coating the fertilizer with a long-lasting, water-soluble polymer. The polymer  prevents positively charged minerals like iron, calcium, aluminum and magnesium from attaching chemical bonds to the negatively charged P, making it unavailable for plant uptake.

The coating naturally breaks down, protecting P through a growing season and leaving no environmental impact. The problem with P fixation occurs in the soil, not the crop, and AVAIL has been shown to have a response in numerous crops — corn, cotton, soybeans, wheat, alfalfa, potatoes, rice, onions and sugar beets, to name a few.

Having those nutrients available when the crop needs them is very important, Moore points out.

“With corn, you have one chance to make an ear, but cotton and peanuts could be drought-stressed for six weeks and still make a crop,” he says. “Corn has a very expensive fertilizer process, so you need to do everything you can to make sure it’s there when the crop needs it.”

Moore, who put 15- to 20-acre sections of AVAIL treated P in his fields and compared it to untreated P, says he’s seen significant yield bumps in his corn fields by using AVAIL.

“You could watch the yield monitor. In some places, it was 10 to 15 bushels better; and in some places, it was as much as 50,” Moore says. “I’m real confident in saying that we averaged 25 bushels better on those fields because of the AVAIL.”

The economics of using AVAIL on his corn fields is a no-brainer, Moore says.

“If you average 25 bushels to the acre on $6 corn, that’s a $150 revenue jump. It’s hard not to make a product pay for itself with numbers like that.”

Moore also uses NutriSphere-N to make sure his N is available at the right time for both his cotton and his corn. NutriSphere-N helps maintain N in the more stable ammonium form longer, which means less volatilization, less leaching and more usable nitrogen to aid in the health and development of the plant. He does split application on both his corn and cotton to minimize N losses. With his spring applications, he first has his N treated with NutriSphere-N to keep it in place longer.

“You can see and understand NutriSphere-N,” Moore says. “I’ve seen fields stay greener and look better through the growing season. It’s worked so well and has been so economical that I just put it on everything now. I know that it keeps my nitrogen in place longer; and since I use urea, that’s especially important. You can lose urea almost as soon as you put it down without NutriSphere-N to keep it in place.”

McCormick agrees farmers must use every tool at their disposal to be effective and efficient with their nutrients. It’s not only an environmental imperative; it’s an economic one.

“N and P are extremely expensive now and we have to use every tool to apply them as efficiently as possible so there is none or very little escaping,” he says. “No farmer wants to lose N or P. Making sure farmers have the best tools available to control nutrient losses is the key to effective nutrient management.”

Visual Difference

Planning a successful nutrient management plan takes a bit of time, but after a while you realize it’s just something that takes regular maintenance. Steve Moore, who farms near Blakely, Ga., knows managing nutrients is a continuous process that takes tweaking as you go. Moore uses grid sampling to tell him from where he’s starting, but he knows that the other important element is where he wants his field to take him.

“I don’t rely entirely on soil samples,” Moore says. “That will tell you what you’ve got, but there is no need to put a lot [of fertilizer] out there if the land does not have the potential. If you only have 150-bushel-to-the-acre corn, there’s no need to put 250 bushels worth of fertilizer out there.” Some of Moore’s southwestern Georgia farm is irrigated and some is dryland. He farms a cotton, corn, peanut rotation. His soils are mostly Tifton, a sandy loam, although some do have a higher clay content. With those sandier soils, he’s very aware of making sure his applied nitrogen (N) stays right where he puts it so it’s available when the crop needs it.

Moore does a split application with both his corn and cotton. Spring-applied N goes out in the form of urea. He’ll usually apply three-quarters of his N in the spring application and come along about two months later and sidedress more urea.

“Urea is highly soluble,” Moore says. “If you don’t get a rain, it starts leaving almost as soon as you put it there. On the dryland, that can mean that it’s just gone.”

One way Moore has fought the loss of N on his land is to treat his urea with NutriSphere-N before application. NutriSphere-N protects against N leaching and volatilization by selectively inhibiting unwanted chemical reactions in the soil. Doing this keeps the N in the more stable ammonium form longer. NutriSphere-N shields N on a molecular level, keeping enzymes at bay. That means less volatilization, less leaching and more usable N to aid in the health and development of the plant.

“I’ve seen NutriSphere-N work,” Moore says. “It levels off your nitrogen for a longer time. I’ve put it side-by-side in a cornfield, and the regular urea outgrew the NutriSphere-N treated urea for the first couple of days. But after that, the NutriSphere-N treated corn caught it and passed it. That corn stayed greener longer and was prettier-looking corn the rest of the season. It’s hard to argue the results when you can see the difference in the field.”