Liming is important for crop production in Minnesota.
When soils are acid, liming increases the ph. Liming to a pH of 6.0 to 6.5 or higher provides an ideal environment for bacteria in soils. Some of these bacteria actively participate in the breakdown of soil organic matter. Others form nodules on the roots of legumes. With this bacterial partnership, legumes are able to utilize the nitrogen in the air.
The need for lime is not uniform across Minnesota and recommendations will vary. Analyzing a soil sample for pH and buffer pH is the only way to arrive at an accurate lime recommendation. Soils should be sampled to a depth of 6 to 8 inches for this test.
Lime recommendations are made on the basis of Effective Neutralizing Power (ENP). The ENP is computed from a laboratory determination of Total Neutralizing Power (TNP) and a particle size analysis. The particle size analysis provides an indication of the length of time that it takes for lime to dissolve and react with the soil. The analysis for TNP and particle sizes applies to the normal limestone materials as well as by-product materials that have some liming value.