horizons
what is O-horizon
Leaf litter, most soil organisms and partially decomposed organisms
rank clay sand and silt biggest to smallest
sand, silt, clay
spodosols
Found under coniferous (pine) forests
Acidic and nutrient-poor
Have a light, ashy E horizon from leaching
Often located in cool, moist climates
conservation tillage
farming practice where the soil is disturbed as little as possible. reduces erosion, maintains top soil
drip irrigation
Pipes with tiny holes allow water to specific plants
▪Frequent, but small amounts of water
▪Good for shallow, sandy soil (low water storage, high infiltration rate)
▪Prevents salinization of irrigated soil
▪Expensive, so typically used in small scale farming
whats a-horizon
topsoil, dark and rich in accumulated organic matter and humus – mixed with mineral particles
coarse textured soil
high in sand, high permeability and aeration
alfisols
Moderately weathered soils
Found in temperate forests
Fertile and good for agriculture
Have a subsurface clay-rich horizon (Bt horizon)
crop rotation
planting different crops in the same field in a planned sequence (one nutrient depleting, one nutrient giving). helps replenish nutrients after harvest
flood irrigation
farmer floods entire field with water.▪Drawback – soil erosion and a lot of water lost to evaporation. Can increase salinization.
whats e-horizon
(Eluviated… washed out) heavily leached; depleted of soluble minerals and nutrients - (not always present) only in older, well-developed soils
fine textured soil
high in clay, low permeability (ability to drain), low oxygen levels, able to hold onto plant nutrients
mollisols
Found in grasslands and prairies
Extremely fertile (one of the best for farming)
Thick, dark, nutrient-rich A horizon
High in organic matter
agroforestry
intentional integration of trees and shrubs with crops or livestock on the same land. helps nutrient cycling and helps IPM
furrow irrigation
trenches are dug between rows of crops and flooded with water. ▪Drawback – soil erosion and a lot of water lost to evaporation. Most likely of all methods to result in salinization.
b-horizon
(subsoil) “zone of accumulation” in which nutrient minerals that leached out of the topsoil and litter accumulate; rich in clay, iron minerals and organic matter which has leached from upper layers by rainwater
aridosols
Desert soils
Very dry, low organic matter
Limited horizon development
Require irrigation for agriculture
intercropping
planting two or more crops together in the same field at the same time. increases productivity, alternative to monoculture which can lead to nutrient depletion
spray irrigation
most common – large scale sprinklers. More expensive than flood or furrow irrigation. Has evaporation, but loses less water than flood or furrow
c-horizon
beneath the B-horizon, contains weathered pieces of rock; it is beneath the extent of most roots and is often saturated with groundwater
oxisols
Highly weathered tropical soils
Found in humid tropical rainforests
Very old, nutrient-poor, and rich in iron + aluminum oxides
Low fertility due to heavy leaching
ground cover
refers to plants (like clover, rye, or grasses) grown to cover the soil surface when main crops aren’t growing. helps replenish nutrients