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Project Identifies Optimal Sampling Levels for Soil Health Indicators

In northern New York, Cornell University Cooperative Extension researchers worked with farmers to identify optimal sampling levels for seven key soil health indicators. The project, funded by a Northern New York Agricultural Development Program (NNYADP) grant, will help more accurately assess the restorative effectiveness of farms’ efforts to improve soil health over time. In this research soil-sample analysis determined the number of samples needed to detect a 10% improvement in soil health based on soil pH, soil organic matter, surface hardness, subsurface hardness, within-field phosphorus, aggregate stability, and soil respiration. The number of samples needed varied widely across the indicators under evaluation. The least variable soil health indicator within a field in this project was soil pH. The most variable within-field soil health indicator was soil phosphorus. As a general guideline, based on this project’s findings, the researchers suggest a minimum of 40 to 50 sub-sample locations per field for farmers who wish to begin monitoring soil health status and improvements over time on a broad scale. To evaluate individual soil health components, more intensive sampling can be done.