W4 - Topic 6 pH & Soil Water Flashcards
What is one of the 5 major soil components that is essential for plant growth?
Water
Essential for processes such as germination, photosynthesis, and nutrient transport.
What are the four forces acting on water in soil?
- Gravity
- Cohesion
- Adhesion
- Surface Tension
Define Gravitational Water.
Water that flows through soil profile after rain or irrigation and drains away relatively quickly.
Define Capillary Water.
Water held between particles after gravitational water passes through, primary source for plants.
Define Hygroscopic Water.
Water tightly adhered to soil particles that plants cannot absorb.
What is Infiltration Rate?
Speed at which water enters soil, highest when soil is dry.
What can improve Infiltration?
- Decompaction/cultivation
- Improving soil structure
- Stabilizing dispersive clay
- Adding mulch or ground covers
What is Hydraulic Conductivity?
Rate of water movement through soil profile affected by texture, structure, and compaction.
Describe Capillary Movement.
Movement of water through fine pore spaces against gravity, stops at field capacity.
What is Saturation in soil moisture concepts?
All pore spaces filled with water, may create anaerobic conditions.
What is Field Capacity?
Moisture status after soil has been saturated and freely drained.
What is Water Repellence?
Inability of soil to absorb water, common in sandy soils.
Define Capillary Fringe.
Saturated zone above a water table containing no free water.
What is a Perched Water Table?
Saturated zone at the interface of finer textured soil above coarser textured soil.
What is the simplest form of Subsurface Drainage Systems?
Trench filled with aggregate to remove infiltrated water.
What does pH measure?
Hydrogen ion (H+) concentration.
What is the range of the pH scale?
0-14, with 7 being neutral.
At what pH are most nutrients optimally available?
pH 6.5.
What happens to micronutrient availability at high pH?
Micronutrients become less available.
How does soil pH affect biological activity?
It impacts biological activity in soil, influencing nutrient availability.
What is one method to raise soil pH?
Add ground limestone (calcium carbonate - CaCO₃).
What is a method to lower soil pH?
Add sulfur (agricultural/dusting sulfur).
What is the application rate to change pH by one unit in sandy soil?
25g/m².
What natural processes contribute to soil acidification?
- Application of acidifying fertilizers
- Leaching of nitrate nitrogen
- Accumulation of organic matter
What is the effect of aluminum toxicity?
Increases at very low pH.
What is the impact of soil texture on pH adjustment?
Clay soils require more amendment than sandy soils due to higher buffering capacity.
