Management Unit Soil Sampling On Diverse Organic Farms.

Soil samples provide useful information to farmers about the nutrient status, pH, exchange capacity, and organic matter content of their soils.  To effectively direct application of soil amendments and fertilizers based on these data soil samples should be taken from distinct management units. Because of the high spatial variation in plantings on typical small organic vegetable farms, it quickly becomes apparent that sampling each management unit each year is not realistic.  We tested a method of sampling representative units from each field.  In fall 2010, we sampled 29 representative management units on 4 different organic vegetable farms of varying size.  Management units ranged in size from 0.035 to 1.16 acres.  Soil test data indicated high or excessive nitrate in 41% of the management units and also revealed spatial gradients in organic matter and pH across the farms. This sampling approach increases the farmers’ ability to track changes in soil conditions caused by management over time.