Aerial Photos Give Clues For Improving Fertilizer Application

Aerial Photos Give Clues For Improving Fertilizer Application

Farmers participating in Iowa On-Farm Network should check imagery for tile lines and N applicator errors.

Most Iowa corn and soybean growers are concerned about the lack of soil moisture, a situation that is continuing with very little rain falling in the state after last summer's drought. Now that most fall field work has been completed and planning for next season is in full swing, reviewing imagery of your fields from past years may be helpful.

BIRD'S EYE VIEW: If you've been involved in the Iowa Soybean Association's On-Farm Network field trials in recent years, you can find useful information by looking at aerial photos that were taken of your fields in years past. The photos can show tile line locations and nitrogen applicator errors. One of the lessons many farmers have learned is that nitrogen needs to be more uniformly applied throughout fields.

"If you've been involved with the Iowa Soybean Association On-Farm Network or have followed our work, you're aware that we value the use of aerial imagery for a number of different applications," says Tracy Blackmer, director of research for the On-Farm Network. "One of the many uses for this imagery is assessing at the uniformity of N application. The technology has improved so that late season aerial imagery can be taken with fine enough resolution that problems with a single row can be detected.



"This article shows an example of an aerial photo shown at a grower group meeting we held two weeks ago that illustrates a problem with an application of urea," says Blackmer. "The green streaks show the pattern the fertilizer applicator made, including the turns in the headlands. Knowing that that there was just a single application in this field, it was not double spread, you can determine that the edges of the applicator put on more of the product than in the center. The narrow yellow strip between the dark green strips confirms that the application passes did not overlap."

Check historic imagery for tile lines and N applicator errors

Horizontal striping shows the extent of the application problems with dry urea last spring on this irrigated field.

He adds, "Over the years, we have seen problems with almost every type of applicator. But to see these differences in N application, we need to see N stress. The last two years have been relatively dry, resulting in less N stress than the four proceeding years." Aerial imagery collected in past years (and with some different soil moisture conditions) for many Iowa counties is available free for viewing. Blackmer's advice: "As you're planning for the 2013 growing season, reviewing the free historic aerial imagery of your fields from previous wet years could help you spot equipment and application problems that need your attention. There are many examples of what can be learned from reviewing the aerial imagery on the On-Farm Network website. Contact the On-Farm Network  for help in determining the cause of patterns you may discover."

TAGS: Soybean
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