Soil Tests and AmendmentsUnit 1.11 | 15
Students’ Lecture 2 Outline
c) Iron (Fe): The extractable amount of Fe (in ppm) found in a given soil sample
i. Optimal levels of available Fe: 11–16 ppm (DTPA extraction)
d) Copper (Cu): The extractable amount of Cu (in ppm) found in a given soil sample
i. Optimal levels of available Cu: 0.9–1.2 ppm (DTPA extraction)
e) Boron (B): The extractable amount of B (in ppm) found in a given soil sample
i. Optimal levels of available B: 0.6–1.2 ppm (hot water extraction)
f ) Plant tissue testing is the most accurate way to gauge adequate micronutrient levels.
See A & L Agronomy Handbook in Resources section.
- Excess lime: A visual observation and rating of carbonates in a soil sample. High levels of free lime
present may interfere with nutrient availability. - Soluble salts: Total measurement of soluble salts by electrical conductivity. High levels indicate
higher risk of plant toxicity due to salt accumulation from fertilizers, poor irrigation water, or
chemical contamination.
a) Optimal levels of available soluble salts: Less than 2.0 mmhos/cm
- Chloride
- Soil texture: The relative proportions (percentage) of sand, silt, and clay particles measured
in the soil anslysis