SSC 461 Exam 1

quartz

Particle density of mineral soil is often assumed to be approximately 2.65 g/cm3, which is similar to the density of ___________.

Sand, Sandy Loam, Silt Loam, Clay

Rank the following soil textural classes from highest to lowest in terms of optimal bulk density for plant growth ( clay, sandy loam, silt loam, sand)

porosity

As bulk density increases, ___________ decreases.

bulk density, porosity, water content

Among the following properties, which can be readily changed by management (particle density, bulk density, porosity, water content, texture, specific surface area)

Volume water content

For a mineral soil, which is typically larger : mass water content or volume water content

.1 cm3/cm3

In order to provide adequate aeration for plant growth, soil air-filled porosity should be at least ________.

2 mm

Based on the USDA classification system, mineral particles considered soil have a max diameter of ___________.

Clay loam

Soil with 30% silt and 40% sand has texture _________ according to the USDA system

size and shape

Specific surface area is primarily related to particle __________, _________ for mineral soils

Silty clay, Sandy clay loam, silt

Assuming they have the same mineraology, rank the following soil textures from highest to lowest in terms of specific surface area ( silt, silty clay, sandy clay loam)

force of buoyancy, force of drag, force of gravity

Name the three forces acting on a soil particle in suspension during sedimentation

0.05 mm

Sieving is typically effective for separating particles with a diameter of _________ or larger from other soil particles.

kaolinite

1 : 1 type clay

montmorillonite

Isomorphic substitution in Al octahedral sheet

illite

Interlayer forces are from fixed K+

montmorillonite

High shrink-swell potential

illite

Intermediate CEC

kaolinite

Low SSA

Flocculation

____________ is the term referring to 'grouping together' of clay particles

valence and solution concentration

Two primary soil solution factors determining the thickness of the DDL are ___________ and __________.

dispersed

A thick DDL will cause clays to be __________.

soil structure, contributes to CEC, holds water

List three primary functions of soil organic matter.