With the assistance and cooperation of numerous private and public soil testing laboratories, the International Plant Nutrition Institute (IPNI) periodically summarizes soil test levels in North America (NA). Soil tests indicate the relative capacity of soil to provide nutrients to plants.
Therefore, this summary can be viewed as an indicator of the nutrient supplying capacity or fertility of soils in NA. This is the tenth summary completed by IPNI or its predecessor, the Potash & Phosphate Institute (PPI), with the ﬁrst summary dating back to the late 1960s (Nelson, 1980). The summary offers a snapshot view of soil test levels in 2010, but also provides a comparison to the previous two summaries which were completed in 2001 and 2005 (Potash & Phosphate Institute, 2001; 2005). Since the 2010 summary is the third summary in which laboratories were asked to contribute complete frequency distributions of soil test results, temporal trends in soil test level distributions can be viewed for states and provinces.
Important to appropriate use of this report is recognition that nutrient management should occur on a site-speciﬁc basis where management objectives and the needs of individual ﬁelds and, in many cases areas within ﬁelds, are recognized. Therefore, a general soil test summary like this one cannot reﬂect the speciﬁc needs of individual farms. Its value lies in calling attention to broad nutrient needs, trends, and challenges, and in motivating educational and action programs that are in turn relevant to growers and their advisers.