Complete List of Terms and Definitions for Soil and water

Terms Definitions
Methods of irrigation? -http://nrcca.cals.cornell.edu/soil/CA3/CA0324.php-Furrow: bring water in highest part of field that flows down along furrows(entle slope); problems- not enough water= not going far enough down furrow, too much=erosion, overwaters beginning underwaters end.-Flood: level field w/ dike around it, flood 4-6 inches-Subsurface: humid climate, drained fields, underground piping of drip system directly to roots.-Sprinkler: most common, good water application control, doesnt alter land, however expensive equipment-Center-pivot: huge circles of landscape w/ lock in center rolls around circumference.-trickle/drip: popular in orchards, little pipes w/ small amount of water used, good water conservation, problem is pipes stop up w/ algae
Alluvium vs. Colluvium Alluvium= material along streambanks.colluvium= material accumulating on hillsides, didnt make it down to streams.
Hazards of irrigation -high cost-Spread water-related diseases-productivity loss caused by increased erosion and EXCESS SALT ACCUMULATION
Who creates soil surveys? Natural resources Conservation Services.-started in 1899, mapped soils directly on topography.-1950-70's, got mucher better: showed land best for farming, urban development, etc.(class 1_) & land not even good enough to walk on (class 8)
types of grassed waterways? -triangular cross section/trapezoidal: sharp angle, deeper= more stream power, must be VERY low V-angle to work-Parabolic: Best option, hard to create w/ straight blade machinery
What is texture? Particle size, sand,silt or clay? determines acquisition, retention, transmittion of water.
Advantages/disadvantages of terraces Pros: shorten slope length, reduce rill/gully erosion, seeds/plants less damaged by water runoff Cons: can be more damaging from veriticle falls from one terrace to next, water can sit in channels and keep soils moist reducing crop yieds,
What is strip cropping? -Growing crops in a systematicarrangement ofstrips across a field. Typesof strip cropping includecontour, field or buffer.-purpose:Reduce soil erosion fromwater• Reduce the transport ofsediment and other waterbornecontaminants• Reduce soil erosion fromwind• Protect growing cropsfrom damage by windbornesoil particles• Improve water quality-How does it work:Strip cropping is effectivedue to the precisearrangement of the alternatingstrips in the field. Thecrops are arranged so that astrip of grass or close-grow-ing crop is alternated witha clean-tilled strip or a stripwith less protective cover.Generally, the strip widthsare equal across the field.
Measurements of Area:-Acre in feet-Mile in acres-Hector in acres-Kilometer:Miles-Mile:kilometers -Acre:43,560sq ft(size of football field including sidelines.-Mile: 640acres-Hector: 2.5 Acres-Kilometer: 0.62 Miles-Mile: 2.7 km sq
What is avg soil loss tolerance? 2-5 tons/acre-year(T-FACTOR)--1 ton= 200lbs-Soil regenerates 1 inch/century!
What are drop structures? water pours out of concrete box-expensive-concentrates slope below structure, needs proceeding structure to absorb energy-helpful if done right but not easy-Common in urban development, roadside ditches.
whats the difference between permeability and infiltration? -permeability: ease of movement through soil-infiltration: ability to enter soil
Types of terracing(3) -Bench: sharp rise, 90 degree benches of stone wall separating rows, VERY intensive, move a lot of earth $$$, expose subsoil, require maintenance, harbor pests, not equally spaced so its hard for machinery to get through, rare in present US.-Steep back-slope:Think of as REALLY WIDE contour, ditches,holds water in LARGE ridge gaps, to remove you can move off laterally to side of field to grassed waterway, expensive way is to install subsurface piping(‘Tiling’) that drains off water underground into harmless place, harbor pests, Better be able to make some $$$!-Mangum: modern, used on mild slopes, change soil profile, but can go across w/ equipment, although this can wear down terraces and require rebuilding, most common.
Types of drainage/Pros & Cons -Surface:. Surface drainage is accomplished by smoothing out small depressions (land smoothing) or regrading an undulating land surface to a uniform slope, and directing water to a natural or improved, constructed channel.-Pros:minimize ponded water near crops, and saturated anaerobic soil, best for flat land w/ slow infiltration & low permeability possibly from a restricting soil layer preventing the infiltration of high intensity rainfall.-Cons: if not done properly soil erosion may occur.-SUBSURFACE or "Tile" drainage: removal water in subsoil and controlling water table depth below crop root zone. Done by burying plastic or TILE conduits. Must be installed below water table so it will flow into lower energy area. -Pros: For humid regions the water table can be lowered so poorly drained soils can responed more like well drained, ARID regions minimize buildup of salinty in root zone.-CONS: $$$
Classes of dams A- rural, if broke no damage downstreamB- rural, but damage can occurC- Serious damage occurs downstream if broken
What are some tolerance factors(T-factors)? Depth of existing soiltype/depth of parent materialfertility of subsoil- always less fertile than topsoil
Types of wind erosion suspension: 1/2 mm & smaller suspended in air, can move 1000's of miles.Saltation: 1/2 mm and up, bouncing across landscape.surface creep: 1 mm & larger
How do streams erode? -Most erosion occurs on banks of streams when wet, water aquires pore pressure, breaks off easily.-Floodplains: Usually don't erode, low slope lots of vegetation.-Wetter then bank, less the strength-Grazers can can erode through hooves or eating vegetation on banks.
Level fields vs. gradient terraces -usually graded because it's cheaper tahn leveling for removing water-want it to move laterally w/o eroding terrces, must have minor gradient, enough to move water but not erode soil(0.4%/ max length 2000ft)
types of plows -mowboard: cut through soil & flops it over, makes soil rough-lister: sharp edged, throws soil to either side, creates ridges for wind erosion prevention-disk: makes small pieces out of large pieces-chisel: like an arm w/ sharp point, pulled under soil to remove hardpan
Major problems of wind erosion -fine particles sorted & carried off which can cause major loss of nuitrients.-Abrasion of plants & materials-air pollution-deposition.
How are impermeable layers formed? -crusts: caused by impact of raindrops on soil surface, fine particles fil large pores.-plow layer: continual plowing at same depth, below plow layer soil ge3ts compacted.-subsoil: caused by heavy machinery traffic.
What took no till so long? -expensive equipment, took time to develop, developed cheap herbicides
What is a mining "Spoil"? sites near shaft where material is left, can be strongly acidic(pyrite) and toxic
Types of grass for waterways? -Bermude is best but very water consumptive.-constraints: bermuda goes dormant, fescue blooms all winter(good), require watering in dry season.-Must establish grass before it can become water way, may take several years
Reason for earthen dams? -millions in US, form ponds w/ pipe that slowly drains out; pipe height= pond height-trap sediment-stabilize channel upstream/downstream b/c flows slower, more uniformly-stores water for: livestock, irrigation, fishing/recreation, etc
What are underground outlets? take runoff water from low points in terrace/diversion channel & carry beow ground through pipes to safe discahrge area.Pros: reduce erosion, sediment fills gullies in areas, peak runoff rates reduced due to detention storage, increased land availability to to lack of nee for vegetated waterwayCons: COSTLY, can become plugged
Why are there no forests in the midwest? Indians burned them all down.
problems with cows near water -love water! come and go many times daily, especially in summer-break down banks,-reduce resistance by eating vegetation-graze often near water because of higher foliage, shade.
How to stabilize a gully -divert water from head of gully were most erosion occurs-smooth slopes on sides-build temporary dams across to fill with sediment deposits-establish perennial vegetation-fence off area from domestic animals
What is rock gravity density? 2.7 jules, soil is about 1/2 rock so around 1.35 jules.
Why are crops grown on bare soil? -other plants steal nuits, can use no-till & herbicide to kill off, but leave biomass.-herbicides not bad, outweigh costs-fodder crops grown(animal food), removed instead of incorporated in green manure because more profitable to sell, removing biomass removes nuits-Bare soil for orchards: create leaf litter, grasses sometime grow beneat but compete for water, trimmings can be put as mulch(avoid oranges they acidify- make soil hydrophobic(repel water))
What grains get lost in stream erosion? -Sand is most easily eroded, not large enough to resist or small enough for cohesion.-Clay: once loses cohesion, lost in water indefinately.
What are effects of no till on global warming? -increases carbon budget in soil through increased plant/animal life, CO2 from plant growth major holder of gases