18: Soil Aeration 1 Flashcards
What % pore space is considered good soil aeration?
Good soil aeration is >20% of the pore space full of air
What % oxygen in soil is considered aerobic and anaerobic
18-20.5% oxygen concentration in soil is considered aerobic. <2-10% oxygen is considered anaerobic.
Redox potential (Eh)
The tendency for electrons to be transferred from one element to another
When does redox potential decrease?
Redox potential decreases shortly after soil water saturation and is strongly associated with oxygen concentrations
What instances does soil water saturation happen?
Can happen right after irrigation or heavy rainfall (which are occasional and short-lived)
Can happen in low horizons (C or B) that are subject to groundwater, more or less permanently
Characterizes some natural environments like wetlands
Ecological effects of varying levels of soil aeration
Organic matter decomposition slowed in absence of O2
Changes in nutrient solubility and availability to plants
Accumulation of toxic elements
Production of greenhouse gasses (GHG) under anaerobic conditions
Low oxygen effects on plants
Reduced photosynthesis
Reduced nutrient uptake
Reduced plant growth
How can we improve soil aeration
Tillage at the proper soil moisture content creates large pores for faster oxygen diffusion (short-term solution)
Addition of organic matter (long-term solution)
Soil drainage (ditches or pipes)
What are wetlands and hydric soils?
Soils that are water-saturated near the surface for prolonged periods of time during the growing season, producing hydric soils that are characterized by anaerobic conditions
What adaptations do plants that adapt to wetlands have?
Have aerenchyma: widened intercellular spaces leading from the leaves through the stem and down to the roots, which act as a channel for oxygen to the roots and allows the plant to survive
What ecosystem services do wetland soils provide?
Purification of water, flood reduction, and climate regulation: largest terrestrial C stocks
