Turf benefits from organic-N fertilizers, but predicting response can be tricky. Here SLAN which has an effective range of 50 to 400 ppm soil Amino-N, can be very useful.

The Solvita SLAN test has been gaining steadily as word of mouth, research trials and farmer reports show that organic-bound Nitrogen – the kind revealed by the SLAN test- is of real practical significance. At two recent turf-science events in RI and MD, Karl Guillard, University of Connecticut, presented an update of his work of two years testing Solvita CO2-burst and SLAN tests to predict behavior of soils amended with organic fertilizers.

The 2014 UConn report “Solvita® Soil Test Kits To Categorize Turfgrass Site Responsiveness To Nitrogen” can be accessed at here. The UConn team led by Karl Guillard included grad students David Moore, Patrick McIntosh and Xingyuan Geng has found that both the SLAN and CO2-burst related significantly to N-responsiveness measured by turf color quality, chlorophyll and clippings yield.  In the graph shown in the above image, the likelihood of a N-response declined exponentially at Solvita SLAN approached 200ppm. Guillard used Binary Logistic Probability Curves relating SLAN to yield and turf quality and told the 2016 gathering at the Mid-Atlantic Association of Golf Course Superintendents that the “Solvita SLAN test kit shows promise as a predictor of lawn response to N fertilization with a single spring sampling”. The attractiveness of identifying potential response to N fertilization – especially with organic fertilizers with unknown release – should be useful to many growers even beyond turf. In a critical study with University of Illinois, Urbana (not yet published) Brinton’s team has found that Solvita SLAN can correctly identify farm sites which are non-responsive to nitrogen for corn.

According to Will Brinton, test kit developer: “Comparing data we have from North Carolina – Ray Styer’s farm, – Connecticut and now Illinois reveals remarkable similarity in that responsiveness to added N declines sharply as the SLAN test passes the 165 ppm level”. With more time and field trials, the new SLAN test should be ready for real field use to help farmers choose to safely add – or not to add – additional N, and cleaner water may well be the result.