New technology could give no-tillers the results of PSNTs in only minutes, helping them get more out of sidedressing applications in corn.

Pre-sidedress nitrate tests (PSNTs) are an emerging method to help no-tillers make more accurate nitrogen recommendations at sidedressing time for corn in the four- to six-leaf stage.

The lag time in getting results for PSNTs through a typical laboratory — sometimes a week or more — can be a disadvantage of using the test, especially if big changes occur in the weather while the results are pending.

Mobile Units In Your Area?

Some crop scouts and retailers have mounted NWN units in their trailers and will hit the road in the Corn Belt this year. Check with a local retailer or call 1-855-GO-SOLUM.

But a new rapid test developed by Solum Inc. to calculate residual nitrate levels in fields could help no-tillers get more timely results from the tests. Solum borrowed a technique used in oceanography that utilizes ultraviolet light to look at the absorption of nitrate-nitrogen in moistened-soil samples.

With Solum’s “No Wait Nitrate” rapid system, soil samples are blended with water. The slurry is processed by a self-contained machine and measured by an optical device to show what the levels are in parts per million (ppm).

The system can be used for a variety of nutrient management and monitoring applications, including PSNT, pre-plant nitrate testing or monitoring nitrogen mineralization and leaching with regularly timed soil sampling.

“The big difference is that we don’t dry and grind the soil samples. If you keep the soil in a moist state, it’s a better predictor of crop response,” says Nick Koshnick, vice president of product management for Solum. “With very little training, the operator can prepare samples, log data and record the readout of soil nitrate on a PPM basis.

“We also have a mobile app available so when we run the samples in the machine, the report comes out with a location and what the value was.”

Finding Leftover Nutrients

Solum was co-founded in 2011 in Mountain View, Calif., by Koshnick, Justin White and Mike Preiner, all physics and engineering students who graduated from Stanford University in 2009. Solum’s technology has attracted nearly $20 million from the software-investment firm Andreessen Horowitz and the green-tech investment firm of Khosla Ventures.

The company’s operations are now based in Ames, Iowa, and has been ramping up its product introductions since last year.

FASTER RESULTS. Solum Inc. has developed a self-contained lab and rapid test that processes moistened soil samples and produces figures for pre-sidedress nitrate tests in a few minutes. Some mobile units (right) with this new technology are expected to hit the Corn Belt this year.

At the company’s Ames lab, the moist-soil method is used to calculate soil nutrients and micronutrients for interested growers. The data from both services is accessible via the Web.

The equipment and software is being sold to farmers, ag service providers and agronomists, mostly in the Corn Belt. While some units are installed in offices, a few Solum customers have installed the equipment in trailers and turned them into mobile soil-testing units.

Several of these mobile units will be located in the Corn Belt this spring and summer. Farmers interested in the technology can ask their retailer about whether they offer it or call 1-855-GO-SOLUM.

Due to last year’s drought, a lower level of nitrogen was likely taken up from the soil by crops and a substantial amount of carryover might be present where weather has remained dry.

“Every year is different, and there’s nothing like having real-time information to help producers know what will work this year,” Koshnick says.

Retired Virginia Tech fertility specialist Mark Alley spoke briefly about Solum’s technology at the 21st annual National No-Tillage Conference last January as he emphasized the need for nitrogen management to be a “year-round sport” for no-tillers, including detecting residual nitrate levels before sidedressing corn.

Pre-sidedress soil nitrate tests have been calibrated and available for years, but it’s been a logistical challenge to get the samples run, Alley says. The Solum technology offers a chance to get more timely results.

"You take a foot-deep sample, walk it over to the instrument, fill it up and 2 minutes later you’ve got a test result. So you can get the data back very quickly,” Alley told no-tillers in Indianapolis. “That sample can then be sent on to a lab to do potassium and phosphorus testing for your fall applications, if you want to do it.”

Put To The Test

Colorado State University in 2011 published the results of a study of 30 soil samples to evaluate the Solum Tech’s nitrate-analysis system on field soils and find out more about the method’s precision and potential detection limits.

The study of split samples, representing grid points of two fields, found a general agreement between results from Solum’s moist-soil method and the cadmium (Cd)-reduction method used on samples at Ward Laboratories in Kearney, Neb.

“Overall, there was very good agreement between the two methods equal to what one would expect between two separate laboratories performing nitrate analysis on 30 samples,” says Colorado State affiliate professor Robert Miller.“Based on these results, we estimate the instrument detection limit (IDL) for the Cd reduction method to be 0.19 ppm and 0.5 ppm for the Solum method.

“Further work is needed to resolve the IDL of the Solum method to determine whether it is equal or superior to the Cd-reduction method.”