Dirty Hands, Fertile Land: Late Spring Nitrate Testing

My name is Hannah Corey, and I am a sophomore in Agronomy at Iowa State. I was raised on a farm near Lake City, Iowa along with my brothers, some cattle, and a whole lot of corn and soybeans.

MeetTheInterns-HannahI am a soils nerd. I like to read about it, talk about it, and think about it, but most of all I like to get my hands dirty and work with the soil. Thankfully, as an intern for Water Rocks! and the Iowa Learning Farms, I get to do all four! I spent this past week traveling to the Iowa State University Research Farms and collecting soil samples for the Late Spring Nitrate Test. Here’s what I learned…

The Late Spring Nitrate Test is used to determine the amount of nitrate in the soil available to corn plants in late spring when the corn is 6-12 inches tall (we sampled statewide this past week, June 6-10). It’s a straightforward process designed so that farmers can do it in their own fields without much hassle.

The tools of the trade are simple: a soil probe, a clean bucket, and a bag to put the sample in.

Our plots on the research farms are no-till and alternate between single-species cover crop, mixed-species cover crop, and no cover crops. In each plot we pull eight different soil cores and mix them together to form one composite sample. Each core is a standard 12 inches deep and ¾ inch in diameter. We pull cores in a diagonal line across the plot to get a sample that accurately represents the area.


Added bonus: it’s also a great arm workout!

After the samples are bagged and labeled, they are sent to the lab to be analyzed for the nitrate content of the soil. The Iowa Learning Farms team uses this data for research, but with data from their own fields, farmers can also use the Late Spring Nitrate Test in their operations.


A composite sample from the Nashua Research Farm bagged, labeled, and ready to go!

A Late Spring Nitrate Test can tell a farmer how much nitrate is available to their corn, and whether or not they need to apply additional nitrogen fertilizer. If the soil is low on nitrate, farmers can help their corn by supplying the additional nitrogen it needs to grow. If the soil has adequate or high nitrate levels, they can save money and keep nitrates out of the water by refraining from adding excess fertilizer.

To me, the Late Spring Nitrate Test is a win-win-win situation. Proper use of the data collected can help boost corn growth, save money, and improve water quality.

HC-SoilSo dig in, get your hands dirty, and learn about your soil. The more we know about our soil, the more we can do to improve its fertility. After you’ve dug in and your hands are covered in soil, remember, “Dirty hands, fertile land!”

Follow our new #dirtyhandsfertileland series on Facebook and Twitter throughout the summer to learn more about what you can do to improve soil health and fertility!

Interested in learning more about the Late Spring Nitrate Test or having your soil tested? Click on these links to learn more…

Nitrogen Fertilizer Recommendations for Corn in Iowa
(free PDF download from ISU Extension Store)
ISU Extension Specialist Suggests Late Spring N Test For Corn
ISU Soil and Plant Analysis Laboratory

Hannah Corey


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