Managing nitrogen is an ongoing process
By Jennifer Bremer
Managing nitrogen fertilizer is an ongoing process according to University of Delaware nutrient management specialist Greg Binford.
"Managing nitrogen fertilizer is not something you can do the same each year. The ongoing process includes a plan, executing the plan, evaluating the success and adjusting the plan," he said at the On-Farm Network Conference in Ames, recently. "It's a continual process."
Using the proper fertilizer is more than just doing what was done the year before. Binford said the process requires several decisions, including using the right product, at the right rate, at the right time, in the right place, in order to meet the goal of maximum efficiency to get the maximum profit, while minimizing environmental problems.
Binford said to determine the proper rate of fertilizer application it is important to look at history. Knowing what amount was applied in previous years and the conditions of the crop as well as all the other environmental factors can be important for making decisions.
The assistance of a crop specialist can help farmers make decisions when they are unsure of how much to apply.
"Farmers should know what that amount of nitrogen is per bushel of expected yield," he said. "The economic optimum rate is the point where the last increment of nitrogen applied is paid for by the increment of increased yield."
Binford said finding that point has been determined by market price for corn and nitrogen and that point will be different each year.
New nitrogen recommendations are based on average nitrogen response and the economic optimum rate, or the maximum return to nitrogen.
"Nitrogen should not be thought of as a number, but instead a process," he said.
Proper timing of nitrogen application can make a big difference in success. Binford said applying nitrogen as close to plant uptake as possible will minimize the risk of nitrogen loss.
Soil type and the amount of moisture in the soil can be two huge factors as to proper timing, as well.
He said making the decision of the proper product to use can be determined by analyzing the big picture and deciding how the nitrogen should be applied.
Anhydrous ammonia, urea, UAN, ammonia sulfate, ammonia nitrate, ESN, or nitrogen stabilizers are all options for nitrogen products. The proper product selection should be based on crop, price comparison and application timing.
Binford said diagnostic tools could become of more value to farmers as the cost of nitrogen increases. Measuring nitrogen levels in soil can assist farmers in knowing what type of product and amount to use.
Remote sensing becomes important during the growing season. Aerial imagery and crop sensors can show differences in how fertilizer has affected the plants based mostly on plant color. Site specific knowledge allows farmers to find problem areas in fields and make adjustments in order to maximize yields.
Binford said the true test of success is yield totals at the end of the year, but that is also the time to make the assessments and consider what changes need to be made for the following year.
Testing for nitrogen amounts in corn stalk and soil can provide important feedback, as well. Once the test results are acquired, the results should be analyzed. These results provide a feedback mechanism in order to make comparisons and changes.
Weather data must always accompany any test results, however, as excessive weather conditions--flood or drought--can cause extra stress to the crop.
"As a rule, farmers should collect data for three years before making major changes in their operation," he said.
Binford concluded by telling farmers to follow the plan, execute, evaluate and adjust strategy in order to know how to properly manage nitrogen fertilizer.
Jennifer Bremer can be reached by phone at 515-833-2120 or by e-mail at firstname.lastname@example.org.