soil Flashcards
what is soil?
the collection of natural bodies on the earth’s surface supporting or capable of supporting plants
what is ideal soil made of?
from an agricultural perspective, an “ideal” soil is made up of 45% minerals, 5% organic matter, and 50% space, with the space filled half with water and half with air
what is parent material?
solid matter making up a soil; influences soil proper ties such as texture, pH, and fertility
what are residual soils?
remian at the site of formation
what are transported soils?
transported from site of parent material(s)
what is climate in soil formation?
-temp and precipitation strong impact on soil formation
-a hot, wet climate- thick layer of chemically weathered soil
-cold, dry climate produces a thin mantle of mechanically weathered debris
-precipitation influences leaching and thereby affecting soil fertility
-climate conditions are important factors controlling the types of biota present which in turn influence soil formation
how does time effect soil formation?
-weathering for a short time- parent material strongly influences the characteristics of the soil
-as weathering continues, the influence of parent material on soil is over-shadowed by the other soil-forming factors
what is biota?
-plants and animals supply organic matter to the soil
-microorganisms play an active role in the decay of plant and animals
what is topography?
-length and steepness of slopes significantly affect the amount of erosion and the water content of soil
-e.g. waterlogged soils in poorly drained bottomlands have large quantity of organic matter that accumulates because saturated conditions slow decay
what are soil horizon?
vertical differences divide soil into layers
what is the soil profile?
vertical section through all soil horizons
what is the O horizon?
-upper layer of O -recognizable plant litter
-lower layer of O partly decomposed organic matter (humus) - plant structures can no longer be identified
-high biodiversity - bacteria, fungi, algae, and insects
what is the A horizon?
-mostly mineral matter
-some humus
-biological activity still high
what is the E horizon?
-contains litte organic material
-water percolates and causes:
-eluviation
-washing out of fine soil components is termed eluviation
-leaching
-water caring soluble materials to depth
-is a light-coloured layer
what is the B horizon?
-where much of the material removed from the E horizon by eluviation is deposited
-often referred to as the zone of accumulation
-accumulation of the fine clay particles enhances water retention in this horizon
-in extreme cases clay accumulation can form a very compact, impermeable layer called hardpan
