L13 Soils Flashcards
What are 4 components of soil
Mineral particles derived from rock
Organic matter
Air
Water
What determines the character of oil
The dominant particle type
What particles do loamy soils contain
When are loamy soils favourable
Intermediate balance between sand, silt and clay
Agricultural purposes
What is the particle content for sandy soil
What is its water content and temperature like
> 50% sand
Easily penetrated by water and air, drains rapidly, poor water and nutrient retention
Warm readily in Spring and cools quick in Autumn
What is the water and mineral content in clay soils
How permeable are they
How does their temperature flluctuate
Retain large volumes of water and minerals
Less permeable
Subject to runoff, poor drainage and aeration
Slow to warm in Spring and cool slowly in Autumn
What are the characteristics of silty soils
Intermediate between sandy and clay soils
What is the shape of the 3 particle types
Sand and silt can be anywhere from irregulat blocks to rounded grains
Clay particles are made up of laminated plates, colloidal
What particle soils have the most pores
Clay
50-60%
What charge do clay particles have and what is the effect of this
Negatively charged and abrorb cations and water onto their surface
In humid regions, what minerals are more abundat
H+ and Ca2+
In arid regions, which is the least abundant
H+
What other soil components can attract water
Cations
What is CEC
Cation Exchange Capacity
How do you calculate pH
-log10[H+]
How can soil pH effect plant growth
Directly - through determining which species are present (calcicoles and calcifuges)
Indirectly - effecting mineral availability and activity of soil organisms
