Module 2: Soil Water Processes Flashcards
(31 cards)
What are soil water processes?
A variety of processes that can happen when water arrives on the soil surface.
1) Puddling/run-off
2) Infiltration
3) Redistribution
4) Percolation/capillarity
5) Storage/Uptake by Roots/Evaporation
6) Drainage
What is the hydrological cycle?
The hydrological cycle is the continuous cycling of water through the atmosphere, the Earth, and back into the atmosphere. It describes the movement and storage of water between the air, plants, soil and open water sources.
Why are soil water processes important?
- SWP enable movement of air and nutrients through the soil.
- SWP are a filter of the water.
- SWP are like a sponge for the Earth, reducing flooding and storing water.
What determines the effectiveness of SWP?
The soil texture and composition.
What is soil porosity?
The capacity for soil to store water.
What is soil water permeability?
The ease with which water can move through the soil.
What are disruptors of SWP?
Soil crusting, soil water repellency, and soil compaction, soil sealing (naturally through e.g. lava or by humans through urbanistion).
What are the consequences of SWP disruption?
Infiltration is inhibited leading to ponding on flat surfaces or run-off on hilly surfaces.
Second, plants can no longer grow which leads to poor quality vegetation or even bear soil. This will eventually lead to erosion.
What is soil wettability?
A soil is wettable when it allows water to move into and throughout the soil.
What are two common problems that reduce soil wettability?
Soil crusting and soil repellency.
What are two key soil wettability processes?
Infiltration & redistribution.
What are the risks when soil is not wettable?
Erosion, pollution, reduced crop performance.
What are the two types of soil crusting? How does “…” soil crusting occur?
There can be biological and physical soil crusting. Physical soil crusting happens because of destruction of the soil structure. Soil particles are are suspended at the surface of the soil and this forms a hard crust.
Which soils are most susceptible to physical soil crusting?
Finer textured soils (high clay content) that are low in organic matter.
How does soil repellency emerge?
A waxy/oily coat emerges on the soil particles due to roots, leaves and soil organisms, often after a dry period.
What is the WDPT test?
The water drop penetration time tests how long it takes for a droplet to be absorbed into the soil.
What soils are more prone to water repellency?
Sandy soils - unsure why exactly…??
What soil texture is more prone to developing severe water repellency?
Sandy soils.
How does soil crusting differ from water repellency?
Crusting is due to the inorganic soil structure whereas repellency is caused by organic material in the soil.
What is soil dispersion?
The breaking down of soil into finer particles.
What is a common cause of soil water repellency?
Fires.
What percentage of soil water repellent material can already disrupt SWP?
As little as 1%!!!
Is water polar or non-polar? And what about soil?
Water is polar, and so is soil, and they are therefore attracted to each other. This attraction facilitates lateral and vertical movement of water through the soil.
What is preferential flow?
Water only flows through channels that are wettable. Preferential flow interferes with effective water distribution.
