Project Identifies Optimal Sampling Levels for Soil Health Indicators
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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.