Testing soil helps to keep the soil healthy by measuring what is exactly in the soil. Soil labs then give recommendations on what to apply to ensure excess nutrients are not available to escape into groundwater, streams and lakes where they contribute to environmental problems (i.e. algal blooms, hypoxia, etc.). A big water quality issue in the State of Ohio that is affecting not only lake Erie but inland lakes such as Buckeye Lake, Grand Lake St. Marys and even Caesar Creek is excess phosphorus. It is important that phosphorus is not added if the soil does not need it. In many parts of the country fertilizer companies are not including phosphorus in their mixes to ensure phosphorus is not over applied.
The field should be walked in a zig-zag pattern, with a subsample taken every few feet. For small areas such as vegetable garden, 5-10 subsamples are sufficient and 10-15 subsamples for larger areas such as lawns and fields. Subsample depths should be taken at the following:
- Field soils – 8 inches
- Garden soils – 6 to 8 inches
- Lawn – 3 inches below turf