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Garden with Insight v1.0 Help: pH

pH is an index that measures the number of H+ ions in the soil solution (H+ ions adsorbed to micelles are not counted). The higher the number of H+ ions, the lower the pH.

In this program the model of pH, cation exchange capacity (CEC), and base saturation (BSA) is very simple. These properties are changed only by fertilization and nitrogen fixation by plants (both of which decrease pH) and by pH control measures (liming and sulfur application). Simulated pH affects nitrification (conversion of ammonium ion to nitrate ion by aerobic soil bacteria) and flow of phosphorus between labile and mineral phases.

In reality pH, CEC and BSA depends on many factors, including: seasonal changes, soil organic matter (its amount and acidity), leaching of cations and anions, plant root activity (plants release H+ ions during respiration, which displace basic cations from cation exchange sites), the local climate, soil texture, soil mineral deposits, and living organisms in the soil. And pH affects many processes in the soil, including the abundance of microbes, invertebrates and vertebrates in the soil, cation exchange capacity, leaching of nutrients, and uptake of various nutrients needed by plants.

How it works:
auto pH control
increasing acidity due to fertilizer

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Updated: May 4, 1998. Questions/comments on site to
Copyright © 1998 Paul D. Fernhout & Cynthia F. Kurtz.