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Thursday, May 09, 2019 Suburban Gardener Western Washington

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This was interesting from Spectrum Analytic about soil test results at http://www.spectrumanalytic.com/doc/library/articles/cec_bph_and_percent_sat

Soil pH: This is a measure of the soil acidity or alkalinity and is sometimes called the soil “water” pH.

Buffer pH (BpH): This is a value that is generated in the laboratory, it is not an existing feature of the soil. Laboratories perform this test in order to develop lime recommendations, and it actually has no other practical value. There is no “GOOD” nor “BAD” buffer pH.

In basic terms, the BpH is the resulting sample pH after the laboratory has added a liming material. In this test, the laboratory adds a chemical mixture called a buffering solution. This solution functions like extremely fast-acting lime. Each soil sample receives the same amount of buffering solution; therefore the resulting pH is different for each sample. To determine a lime recommendation, the laboratory looks at the difference between the original soil pH and the ending pH after the buffering solution has reacted with the soil. If the difference between the two pH measurements is large, it means that the soil pH is easily changed, and a low rate of lime will suffice. If the soil pH changes only a little after the buffering solution has reacted, it means that the soil pH is difficult to change and a larger lime addition is needed to reach the desired pH for the crop.

The reasons that a soil may require differing amounts of lime to change the soil pH relates to the soil CEC and the “reserve” acidity that is contained by the soil. Soil acidity is controlled by the amount of hydrogen (H+) and aluminum (Al+++) that is either contained in, or generated by the soil and soil components. Soils with a high CEC have a greater capacity to contain or generate these sources of acidity. Therefore, at a given soil pH, a soil with a higher CEC (thus a lower buffer pH) will normally require more lime to reach a given target pH than a soil with a lower CEC.

Yup, my social skills are still lacking. Sorry folks.
 



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