Week 4 And 5- Soil Grade And Other Info
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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What is Grade?
determined by handling soil or gently erushing soil -note durability of aggregates
What is SingleGrain soil?
Structureless soil that is broken into individual particles that do not stick together
What is massive soil?
Structureless soil that is hard to break apart and appears in large clods. Commonly found in C horizon
Dry consistent soft (s)
Very weakly coherent and fragile
Dry consistent slightly hard (sh)
-weakly resistant to pressure moderately hard, moderately resistant to pressure
Dry consistent moderately hard (mh)
Moderately resistant to pressure
Dry consistent hard (h)
Resistant to pressure
Dry consistent very hard (vh)
Very resistant to pressure
Dry consistent extremely hard (eh)
Extremely resistant to pressure, cannot be broken with thumb and forefinger
Moist consistency loose(l)
Noncoherent
Moist consistency friable (fr)
Crushes easily with gentle to moderate pressure
Moist consistency very friable (vf)
soil material croshes very gently pressure but coheres when pressed together
Moist consistency firm(fi)
Crushes under moderate pressure but resistance is noticeable
Moist consistency very firm (vf)
Crushes under strong pressure
Moist consistency extremely firm
Crushes only under very strong pressure
Wet consistency plasticity
ability to change shape continuosly under the influence of an applied stress and to retain the impressed shape on removal of the stress
Factors controlling soil aggregation
-Flocculation, soil environment, climate, and management
What is flocculation?
An elemental process that causes small particles to clump together in large clusters. Clays and organic matter have negatively charged surfaces Ca, Mg, Al