Soil Biology & EcologyUnit 2.3 | Part 2 – 95
Lecture 1: Soil Biology & Ecology
- Roots
a) Root environment
i. Determined by above-ground processes (products of photosynthesis are
translocated to roots)
ii. Exudates (see below), sloughed hairs, and epidermal (root’s surface) cells feed soil
organisms in R and r
iii. Plant roots also can release bicarbonate (HCO 3 -), which raises the soil pH. This can
make some cations (e.g., Fe+3, Ca+2, Mg+2, and K+1) unavailable to plants. Irrigation
water may also contain bicarbonate and affect soil pH and availability of some
nutrients.
iv. Oxygen decreases, CO 2 increases in root zone over time due to plant and R organism
respiration
b) Root form
i. Fibrous roots
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ii. Tap roots
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iii. Root depth
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c) Root structure
i. Root cap
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ii. Meristematic zone: 2 mm (.08 inch) zone where most cell division happens
iii. Zone of elongation: Rapid growth, cells from meristem
iv. Mucilage
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with nutrient uptake, prevents drying, fills spaces between root and soil and helps
bind soil aggregates, food for microbes, including beneficial microbes
v. Root hair (differentiation) zone
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per day
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and water uptake. Root hairs make up the majority of root surface area.
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of soil organic matter
vi. Lateral roots
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