Table 1 Some human agents of change in soil properties and processes
Agriculture and Forestry
 Crop and animal agriculture: Tillage, fertilization, cropping,
flooding, irrigation, drainage, terracing, grazing
 Forestry: Altered vegetation type and cover, harvesting
operations
 Off-site effects of these land uses: erosion and sedimentation,
causing soil contamination and burial
Cities and Industry
 Excavation, urban cover, artificial fills, industrial pollution
Buildings, Roads, and Other Structures
 Excavation, artificial fills, pollution, paving, land leveling
 Dams and reservoirs; polders, dikes, mounds, other artificial
landforms and fills
Mining and other Earth and Water Resource Extraction
 Soil removal for pits and quarries, erosion and sedimentation
associated with hydraulic mining, mixing and inversion of earth
materials, reclamation, groundwater pumping
War and weapons testing
 Bomb craters; military transport and engineering; contamination
by radioactive elements
Human-linked environmental change
 Global climate change: Atmospheric CO2 increase; climate
warming and increased climatic variability
 Desertification: Vegetation loss or change; accelerated wind and
water erosion; salinization
 Acid rain: Soil acidification and other chemical changes
Table 2 Kinds of soil change resulting from human impact. Bracketed terms illustrate range end
members.
Causes and Characteristics of Soil Change
Causes of soil change may be:
Direct
Indirect
Examples
Compaction
Slower or diverted water movement and reduced
soil water storage after compaction
Deliberate
Unintended
Fertilization, liming, irrigation
Nutrient depletion or imbalance; salinization
Constructive
Destructive
Plaggen soil; agricultural terracing and drainage
Accelerated erosion, sulfide oxidation with
drainage or exposure, salt/sodium buildup
Magnitude and extent of soil change
Low impact
High impact
Part of soil
Whole soils
Duration and rate of soil change
Short-term/ephemeral
Organic matter change from light grazing
Urban expansion; land filling
Thinning of A horizon from cultivation-induced
erosion
Removal of entire soil by intense erosion
Long-term/ permanent
Alleviation of plow pans by freezing and thawing;
liming
Urban soil; mine soil
Slow rate
Fast rate
Agric horizon development
Oxidation following drainage
Response of soil to human impact
Susceptible
Resistant
Reversible (resilience)
Irreversible
Outcomes of soil change for soil quality and use
Beneficial
Base-poor soil susceptible to acid rain
Base-rich soil buffered against acid rain
Alleviation of compaction is faster in organic
matter-rich A horizons
Laterite/plinthite hardening with exposure;
construction of urban soils and soils on mined land
Organic matter addition
Neutral/benign
Fertilizing that balances crop removal of nutrients
Degradation (loss of productivity/ off site
environmental impacts)
A horizon erosion
Table 3 Spatial scales of human-induced soil change
Soil components
Approximate spatial scale
(meters)
Examples of impacts
Physical, chemical, and
biological properties of soils
(e.g., clay, microorganisms,
organic matter)
10 –10 - 10 –4
Retention of pollutants such as
heavy metals, pesticides, and
industrial solvents
Morphological properties
10 -3 - 10 –2
Soil structure degradation;
changes in texture, color,
porosity and pore distribution
Horizons
10 -1 - 10 0
A horizon erosion
Whole soils (pedon)
10 0 - 10 1
Plaggen soils; salinized soils;
liming that changes Ultisols to
Alfisols
Soil-watersheds-landscapesecosystems-Biosphere
10 2 - 10 7
Broad changes in Mollisols,
Histosols, Gelisols, and other
soil orders