Soils Flashcards
Describe how phosphates contribute to eutrophication
Sewage effluent enters the water, increasing water phosphorus levels which can increase algal blooms which shades macrophytes, preventing photosynthesis.
Why are deeper soils typically more fertile?
They are less likely to become waterlogged or dry out rapidly
What soil type is easier to cultivate and why?
Lack of adhesion between sand particles means easier cultivation than clay
What are loam soils and what is their typical ratio of sand slit and clay?
Loam soils have an even mix of sand, slit and clay, (40:40:20), ideal mix for cultivation
Describe crumb peds
Crumb peds are round and small, producing good drainage, aeration, easy root penetration. Good fertility.
Describe platy peds
Large and flat, reduce drainage, aeration and root penetration, less fertile.
Describe the drainage of each of the two main soil types and how that affects its fertility.
Larger pore spaces of sand allow rapid drainage, reducing water content but increasing aeration, clay soils are poorly drained.
Describe the capillary action of each of the two soil types.
Tiny pore spaces between clay particles allow water underground to surface/rise . No capillary rise of water in sandy soils.
Which of the two main soil types best absorb nutrients and how?
Nutrient ions absorb easily onto clay particles but not onto sand
How does the thermal capacity differ between the two main soil types and what effect does that have?
Clay has a higher water content and therefore higher thermal capacity, sand has a low heat capacity and so will heat up and cool down quicker.
Why is root penetration different in clay soils than in sand?
Clay particles are held together by capillary water on particle surfaces.
Harder for roots to force their way through soil particles
How does DOM incorporated by soil biota benefit the soil?
Increased water retention
Nutrients released during decomposition
Why are soil biota significant in soil health?
Important in aeration, soil mixing, decomposition of DOM, nitrogen fixation.
Why is water important in soils?
Inorganic nutrients are absorbed when dissolved in water
Plants require water to keep stomata open and allow gaseous exchange for photosynthesis
Describe wind blow erosion
Moving air carries dry soil particles. Most likely in dry areas as soil particles aren’t held by moisture
