Chapter 11-Soil: The Foundation for Land Ecosystems Flashcards
Rocks break down into smaller and smaller fragments; could be physical or chemical breakdown of rocks
Weathering
The mineral material of soil that has its origin in the geological history of an area; could be rock or sediment deposited by wind, water, or ice
Parent rock
Fragments of rocks (classified as sand, silt, and clay)
Soil separates
The relative proportions of each type of particle in a given soil (i.e. loam)
Soil texture
A proportion that is commonly found in soil (consists of 40% sand, 40% silt, and 20% clay)
Loam
Made up of particles from 2.0 to 0.063 mm in size
Sand
Particles that range from 0.063 mm down to 0.004 mm
Silt
Anything finer than 0.004 mm
Clay
The ease with which a soil can be cultivated; affected by soil texture
Workability
The horizontal layers in soil profiles
Horizons
A vertical slice through the different horizons
Soil profile
Topmost layer that consists of dead organic matter (detritus) deposited by plants (leaves, stems, fruits, and seeds); high in organic content (humus); primary source of energy for the soil community
O Horizon
Topsoil (mixed humus and leached mineral soil); it is a mixture of mineral soil from below and humus from above; usually dark because of humus
A Horizon
The “E” stands for eluviation, which is the process of leaching; zone of leaching (less humus, minerals resistant to leaching)
E Horizon
The dissolving away of many minerals due to the downward movement of water; when nutrients are literally washes from the soil as water moves through it
Leaching
Subsoil (accumulation of leached minerals like iron and aluminum oxides); characterized by the deposition of minerals that have leached from the A and E horizons; often high in iron, aluminum, calcium, and other minerals; also high in clay and is reddish or yellow in color
B Horizon
Soil order, suborders, groups, subgroups, families, and soil class
Taxonomy of soils
The soils ability to support plant growth (farmers use the term tilth of the soil)
Soil fertility
Phosphate, potassium, calcium, and other ions
Mineral nutrients
The soil’s capacity to bind and hold nutrient ions until they are absorbed by roots
Nutrient-holding capacity/Ion-exchange capacity
Material that contains one or more of the necessary nutrients
Fertilizer
Includes plant or animal waste or both (i.e. manure and compost)
Organic fertilizer
Chemical formulations of required nutrients, without any organic matter included; more prone of leaching
Inorganic fertilizer
Water evaporates from stomata (pores) on the underside of the leaves
Transpiration
Essential to permit the entry of carbon dioxide and the exit of oxygen in photosynthesis
Stomata
Results by inadequate water
Wilting
Soak in
Infiltrate
A property that land plants depend on the soil being loose and porous enough to allow the diffusion of oxygen into, and carbon dioxide out of the soil
Soil aeration
The packing of the world which reduces infiltration and runoff; this occurs with excessive foot or vehicular traffic
Compaction
The acidity or alkalinity (basicity) of any solution; scale=1-14; 7 is neutral pH
pH
A buildup of salts in the soil (increases salinity) makes it impossible for the roots of a plant to take in water
Salt and water uptake
Soils hold carbon from dead organisms; scientists estimate that soils hold as much as three times the amount of carbon held in the atmosphere and living plants
Soil and carbon storage
Describes the size of soil particles
Soil texture
The arrangement of soil particles; a loose soil structure is ideal for infiltration, aeration, and workability
Soil structure
Excrements
Castings
Partly decomposed organic matter; high capacity for holding water and nutrients; typically found in the O horizon
Humus
The process of fostering the decay of organic wastes under more or less controlled conditions, and the resulting compost is essentially humus
Composting
Certain fungi that form from a symbiotic relationship with the roots of some plants; draw some nourishment from the roots, but they penetrate the detritus, absorb nutrients, and transfer them directly to the plant
Mycorrhizae
The loss of humus and the consequent collapse of topsoil
Mineralization of the soil
The process of soil and humus particles being picked up and carried away by water or wind
Erosion
The impact of falling raindrops breaks up the clumpy structure of topsoil
Splash erosion
When running water carries off the fine particles on the soil surface
Sheet erosion
When water converges into small rivulets and streams, which have greater volume, velocity, and energy to carry away large quantities of soil causing gullies
Gully erosion
Process in which the soil loses its nutrient-holding and water-holding capacity causing the soil to be degraded
Desertification
The removal of fine material by wind that has left a thin surface layer of stones and gravel, which protects the underlying soil against further erosion
Desert pavement
Occurs when farmers till and plow their farms to control weeds and increase crop yields; this practice exposes the soil to the wind and rain, which causes erosion
Overcultivation
Occurs when ranchers put large numbers of livestock such as cattle out to graze on arid grasslands
Overgrazing
The forest is cut and the soil is left exposed to erosion
Deforestation
Technique that minimizes soil erosion; farmers use special equipment to turn over the soil while covering it back up and planting new crops at the same time
No-till/low-till
When crops are planted across slopes to slow down water erosion or in “stairs” to stop water erosion
Contour farming/terracing
Technique of planting alternating rows of different crop types
Strip cropping
When trees are planted in strips and the crops are grown between these strips of trees; the trees help to shelter the crops from the wind, and the roots of the trees help to hold the soil in place
Alley cropping
When trees are planted around crops to help shelter them from the wind
Shelterbelts
Provides information to farmers or other interested persons regarding soil or water conservation practices; established in response to the Dust Bowl (early 1930s)
U.S. National Resource Conservation Service (NRCS)
Occur when eroded soil is carried into streams and rivers, causing flooding, killing fish, destroying wetlands, killing coral reefs, and carrying pollutants into the rivers
Sediments
Supplying water to crop lands by artificial means which has dramatically increased crop production in regions that typically receive low rainfall
Irrigation
A technique in which water is diverted from rivers through canals and flooded through furrows in fields
Flood irrigation
A technique in which water is pumped from s central well through a gigantic sprinkler that slowly pivots itself around the well
Center-pivot irrigation
The accumulation of salts in and on the soil to the point where plant growth is suppressed; in dry lands, it is considered a form of desertification, since it renders the land less productive or even useless
Salinization
Below the B horizon which is the the parent mineral material originally occupying the site; weathered parent material (partly broken-down minerals); not affected by the biological and chemical processes that go on in the overlying layers
C horizon
A network of plastic pipes with pinholes that literally drip water at the base of Each plant (reduces water use by 30 to 70% while increasing crop yields)
Drip irrigation
