Farmer-Initiated Soil Testing in an Organic Farm Marketing Cooperative.

Maintaining soil fertility under the regulatory standards set forth by the USDA National Organic Program can be a challenge for organic farmers, depending on the availability and economics of allowed fertility inputs, cover crop opportunities, and practical crop rotations in different regions across the U.S. In order to better advise organic farmer members to help them optimize soil fertility on their farms, for the past five years CROPP Cooperative has undertaken a centrally-coordinated soil testing program. To date, over 500 member farm families have submitted over 1,500 soil samples for testing through the program, with analyses conducted at a private third-party laboratory. The soil samples represent fields managed under diverse crop rotations and pastures, from farms ranging from newly-transitioned organic operations to those under organic management for many years. The data from these soil tests is recorded in a database for ease of tracking and identification of regional trends. Soil test data from member farms in 25 states illustrate trends in soil fertility characteristics and provide useful foundational information on the range of fertility parameters experienced by farmers on a regional level. The most common deficiencies and imbalances identified by these soil tests include low pH, low potassium and phosphorus levels, and micronutrient levels below the target ranges identified for organic farming systems. This data set, which continues to expand with the addition of new samples, could further add to our understanding of the impact of crop rotation, cover crop strategies, and time under organic management on organic soil physicochemical properties, particularly as new tools continue to emerge in “big data” analytics.