The International Plant Nutrition Institute has officially released the results of the 2015 North American Soil Test Summary.

The summary is the most extensive evaluation of the fertility of North American soils ever conducted. It shows status and temporal trends for several critical nutrient and pH components of soil health and provides insights into the sustainability of farming practices.

"Critical to this effort are the contributions of our network of private and public soil testing laboratories that have provided data voluntarily, contributing their own staff time and computing resources. Summaries would not be possible without these generous contributions which we gratefully acknowledge," explains Dr. Paul Fixen, IPNI Senior Vice President and Director of Research.

IPNI, or its predecessor the Potash & Phosphate Institute (PPI) has conducted these periodic summary analyses of soil test data for the U.S. states and Canadian provinces since the 1960s. The 2015 summary marks the eleventh in this series.

IPNI's 2015 soil test summary is the most extensive effort to date. Participating laboratories submitted results from over 7.5 million samples, which far exceeds the previous record of 4.3 million samples gathered in 2010.

The 2015 summary also marks the fourth opportunity to use a common data collection protocol adopted for summaries performed in 2001, 2005, and 2010. Similar to the 2010 summary, soil test data were collected for phosphorus, potassium, sulfur, magnesium, zinc, chloride, and pH.

For the first time, IPNI has released the results of these four most recent summaries within a web-based data analysis system found at This website provides new opportunities to view, compare and contrast soil fertility data over this 15-year time period. The site also provides full access to a range of charts, maps, and tabular data sets.

The release of precedes the upcoming Spring release of IPNI's accompanying 2015 Soil Test Summary Bulletin publication that will provide extensive interpretive analysis of the results.

IPNI also invites all to attend the upcoming webinar by the project's lead scientist, Dr. T. Scott Murrell (2:00pm EDT, Wednesday, April 27). Details will be posted at