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Coordination needed for soil management

By Staff | Jul 14, 2014

JOHN HOLMES, an agronomist with North Central Cooperative, spoke to farmers on July 1 at Hagie Manufacturing, in Clarion, on how to take late-spring nitrogen trial sampling.

CLARION – Just about anything area producers needed to know about nitrogen and keeping in their fields and applied at the correct rates was covered on July 1 at a Wright County Soil and Water Conservation District field day in Clarion.

The SWCD, along with the Boone River Watershed Nutrient Management Initiative, and Hagie Manufacturing, in Clarion, hosted the event, where speakers supplied attendees with up-to-date sources and information regarding nutrient management within the Boone River Watershed.

Bruce Voight, with the Wright and Hamilton County SWCD, said there are demonstration practices that have funding available to assist producers in getting started to prevent leaching and run-off of nutrients.

“The main goal of the Boone River Watershed Initiative is to keep that nitrogen in the field,” said Voight.

One particular practice is cover crops, Voight said.

SARAH CALDWELL, a sales representative with Dow Agrisciences, demonstrates how nitrates leach by water moving through the soil.

Cover crops, he said, can be planned for use this fall or possibly in some of the large drowned out fields that have been created through excessive rainfalls in the past few weeks.

By planting a cover crop in those drowned out areas, Voight said, it will help with weed pressure as well as helping to preserve that land.

Cover cropping, he said, fits in all operations.

“Some think cover crops have to go with no-till or strip-till, and they don’t,” he said.


MIKE OLSON, with Ag Leader Technology, explains new technology making its way onto the marketplace during the Boone River Watershed’s Nitrogen Management and Efficiency Field Day held July 1 at Hagie Manufacturing last week.

Adam Kiel, state water resources manager with the Iowa Soybean Association, said the Boone River Watershed is just one of eight statewide watershed preservation projects that are funded and provide cost-sharing opportunities for producers.

He encouraged producers to look into the cost-share practices that are available.

“They are worth looking in to, even if you live outside of a watershed,” said Kiel.

Kiel said producers who lives within a targeted watershed can join several strip-trials featuring a variety of nitrogen management practices employed within the same field.

“We are currently looking for 20 trials using cover crops and 40 fields to do cornstalk nitrate testing on,” said Kiel. “These provide a feedback mechanism to understand how things are going in your field.”

AG LEADER’S OptRx Crop Sensors have been on the market for about five years. They are designed for mapping and data collection as well as real-time variable rate application for sidedressing nitrogen fertilizer.

In addition to those trials, Kiel said, conservationists are looking for more participants to allow for field water monitoring.

“We have found this is empowering for people to see what is coming out of their fields, it is very informative,” he said.

These results, he added, are shared, but in an anonymous way.

“You will get an idea of how your tile system stacks up against others in the Boone River Watershed and against others in the state,” he said.

A large part of nitrogen management is taking and understanding a late-soil nitrate test.

Soil sampling

John Holmes, an agronomist with North Central Cooperative, said an LSNT should be taken when corn is at 6 to 12 inches in height, or the V3 to V6 stage.

With a soil sampling tool, Holmes said samples should be taken at 12-inch intervals, with 16 to 24 cores taken from similar soils.

After samples are collected, he said, the cores should be broken and mixed thoroughly and stored in a paper bag and kept cool.

He suggested bringing a cooler for storing samples. They should be sent to a laboratory immediately.

To get a thorough sample in a field, Holmes recommended making a rectangle that is 12- to 16-rows wide and 150 to 175 feet long then make an “S” shaped pattern walking through the rectangle taking eight core samples, progressing across the row so not to sample in the same area of each row.

“You only want to hit that nitrogen application zone or the injection zone once,” Holmes said.

Holmes listed several common soil-sampling mistakes, including:

A). Sampling at the wrong time.

B). Failing to get a full 12-inch soil core.

C). Failure to take enough cores.

D). Samples are not taken on similar soils.

E). A pattern was not followed and/or the injection zone was hit more often.

G). Samples got too hot and were not sent in soon enough.

Holmes said when producers receive the LSNT results, the nitrate levels will be will be given in parts per million.

As referenced from the Iowa State University Extension, Holmes noted that no additional nitrogen is required if the results are greater than 25 ppm.

However, if the results are 10 ppm or less, a full rate of additional nitrogen is required; but if the results are between 10 and 25 ppm a calculation will have to be made to determine the amount needed.

Nitrogen trials

Rich Stessman with the Iowa Soybean Association’s On-Farm Network discussed some of the OFN’s nitrogen trial opportunities.

These include:

1). Fall anhydrous ammonia applications versus spring-applied NH3.

2). A normal application with an additional 50 pounds of nitrogen.

3). A normal application with less than 50 pounds of nitrogen.

4). A urea and ammonium nitrate versus NH3.

5). Manure versus other nitrogen sources.

6). Trials featuring other nitrogen sources.

Stessman said OFN is open to other nitrogen strip trial ideas, as well.

“Anything you are interested in and want to try out for yourselves, we would like to help out,” said Stessman.

A few lessons learned, he said, from the 2013 growing season, is researchers found there was a higher likelihood of a deficient nitrogen status for corn after soybean than there was in corn-after-corn situations.

“That hasn’t occurred very often in the past,” said Stessman. “But it did in 2013.”

This could be, he said, if producers over estimated the nitrogen soybeans left behind, or possibly the corn in 2012 didn’t take advantage of all of the nitrogen that was available and it stuck around for 2013.

Other 2013 lessons learned included:

  • Higher nitrogen rates were needed to reach the optimal nitrogen status for fields receiving fall manure applications.
  • Spring UAN applications were at a higher risk of loss than other forms and timing in 2013.

More results of strip-trial summaries, Stessman said, can be found at www.iasfarmnet.com/onlinedb/index.php.


Dow Agrisciences sales representative, Sarah Caldwell, stressed the importance of using a nitrogen inhibitor such as N-Serve or Instinct.

Caldwell said producers must keep their nitrogen in the ammonium form as long as possible to be the most beneficial to a corn plant.

Heat is the biggest culprit for turning ammonium into its nitrate form, she said, which occurs in both fall- and spring-applied nitrogen.

“Temperature affects the conversion of nitrogen, as it warms up, it converts faster,” she said. “When it is warmer at side-dressing time, you could lose all of your nitrogen within a couple of weeks, for example.”

To avoid this nutrient loss, Caldwell said, it is important to stabilize those spring nitrogen applications with an inhibitor.

N-Serve works to keep nitrogen in its ammonium form for 90 days. It will not be necessary in the fall once soil temps have cooled to below 40 degrees. The conversion process stops, and will resume when soils warm in the spring.

N-Serve, Caldwell said, has been on the market for 40 years and research has proven, nationally, that it works.

While her company’s other product, Instinct, has been on the market for five years.

Caldwell said that producers using N inhibitors are growing more corn and using less nitrogen the same amount of acres.

Crop sensors

Mike Olson, with Ag Leader Technology, based in Ames, explained the benefits of using crop sensors to a producer’s nitrogen management program.

Ag Leader’s OptRx Crop Sensors, Olson said, have been available for five years and in testing for seven years. On average, he said, they can produce a $25-per-acre profit, with some producers claiming a $75- to $100-an-acre profit increases, compared to not using the sensors.

The OptRx Crop Sensors, according to Olson are able to measure and record data about crops in real time using the reflectance of light shined on the growing plants.

The sensors, Olson said, can be installed across an application boom to collect information while driving through the field. The data is logged and mapped to be used in further analysis, for real-time variable rate applications.

Olson said producers are still in total control of their nitrogen program by applying the maximum and minimum rate of nitrogen as the sensors depict where the nitrogen gets applied.

Olson said the crop sensors will begin working on corn that is at the V5 stage, because at that particular growth stage, there is enough leafing for the sensors to detect.

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