Assessing the chemistry of soil

Measuring the salinity-related chemical parameters for a landscape's soil can help reveal the presence and magnitude of existing or potential problems involving salinity.

Ascertain the following by sampling the landscape's soil and submitting the samples to a laboratory.

• Electrical conductivity of the soil, expressed in dS/m

  This parameter, denoted EC_e, is determined by measuring the electrical conductivity of water extracted from a water-saturated paste made from a sample of the soil. (The "e" in the abbreviation EC_e stands for "extract.") Greater electrical conductivity indicates greater salinity. Excessive amounts of salt can injure salt-sensitive plants.

• Concentrations of particular ions in the soil, expressed in mg/l

  Ions most often of interest are sodium ion (Na⁺), chloride ion (Cl^-), and ammonium ion (NH₄⁺). Excesses of these can harm some plants.

• Sodium absorption ratio, SAR, or exchangeable sodium percentage, ESP

  These ratios are calculated based on the concentrations of sodium ion (Na⁺), calcium ion (Ca²⁺), and magnesium ion (Mg²⁺). They help indicate whether the soil is apt to become less permeable.

• Concentration of boron (B) in the soil, expressed in mg/l or ppm

  An excess of boron has a deleterious affect on plants.

• pH of the soil, unitless

  The acidity or alkalinity of a soil, as indicated by the soil's pH, affects the solubility of ions and the activity of micro-organisms, both of which indirectly affect the growth of plants.

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