chapter 19 urban soil. problems with urban soils problems differ between rural growers and urban...
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Chapter 19Chapter 19Urban SoilUrban Soil
Problems With Urban SoilsProblems With Urban Soils
Problems differ between Rural Growers Problems differ between Rural Growers and Urban Soil Usersand Urban Soil Users Urban more severeUrban more severe
Extreme variations in soil conditions across a city Extreme variations in soil conditions across a city landscapelandscape Complicates landscapingComplicates landscaping
Soil moving often causes very poor soil qualitySoil moving often causes very poor soil quality
Problems (Continued)Problems (Continued)
Urban soils are improved by adding Organic Urban soils are improved by adding Organic Matter such as:Matter such as: LeavesLeaves Grass ClippingsGrass Clippings CompostCompost Bagged ManuresBagged Manures
Three Traits of Urban SoilThree Traits of Urban Soil
Buried DebrisBuried Debris
CompactionCompaction
ContaminationContamination
Buried DebrisBuried Debris
Contractors often bury wood or masonry scraps on Contractors often bury wood or masonry scraps on the job sitethe job site
Buried scraps may cause:Buried scraps may cause: Restricted drainage Restricted drainage Excessive drainageExcessive drainage A physical barrier to root growthA physical barrier to root growth
Buried masonry, which contains lime, can raise pH Buried masonry, which contains lime, can raise pH to unacceptable levels. to unacceptable levels.
CompactionCompaction Urban Soils are usually moderately to severely Urban Soils are usually moderately to severely
compacted compacted
Compaction can be measured by Compaction can be measured by Bulk DensityBulk Density At a bulk density of 1.7, roots cannot penetrate the soilAt a bulk density of 1.7, roots cannot penetrate the soil
Many of our best urban trees hale from floodplainsMany of our best urban trees hale from floodplains
It is possible to break up compaction if no plants It is possible to break up compaction if no plants
are in the wayare in the way
Ways to Get Rid Of CompactionWays to Get Rid Of Compaction
Deep Tillage
Digging large solid particles into soil
Large amounts of Organic Matter Wood Chips
Leaf Mold
Pave the soil with special pavers and grids that have large
holes built into them Use Of Aerators- machines that remove vertical cores from the soil
For turf, vertical coring to six inches breaks up the soil and
makes passages for air and water movement
Soil ContaminationSoil Contamination Deicing SaltsDeicing Salts
Sodium chloride creates saline or even sodic soil conditions, and Sodium chloride creates saline or even sodic soil conditions, and chloride may reach toxic levelschloride may reach toxic levels
Damages plant tissue directly, especially evergreens, by Damages plant tissue directly, especially evergreens, by desiccationdesiccation
Lead ContaminationLead Contamination Lead added to paint and gasolineLead added to paint and gasoline
Primarily effects children causing permanent brain damage, and even deathPrimarily effects children causing permanent brain damage, and even death Lead found in blood can lower an IQ level by three pointsLead found in blood can lower an IQ level by three points Contributes to high blood pressure in adultsContributes to high blood pressure in adults
Main source of soil lead is automobile exhaust from cars using leaded Main source of soil lead is automobile exhaust from cars using leaded gasgas
Derelict LandDerelict Land DefDef- Land severely damaged by human abuse that it is unusable - Land severely damaged by human abuse that it is unusable
without costly abatement effortswithout costly abatement efforts
Urban ErosionUrban Erosion The impact of construction site erosion differs The impact of construction site erosion differs
slightly from farmland erosionslightly from farmland erosion
Rilled and gullied land must be repaired before a site Rilled and gullied land must be repaired before a site can be soldcan be sold
In extreme cases erosion can In extreme cases erosion can Undercut roadsUndercut roads Collapse roads Collapse roads Collapse foundations Collapse foundations
Contributes to off-site problemsContributes to off-site problems
Controlling ErosionControlling Erosion Keep disturbed areas smallKeep disturbed areas small Protect disturbed areasProtect disturbed areas
On steep slopes, layer of rock (rip-rap) controls erosionOn steep slopes, layer of rock (rip-rap) controls erosion
Keep runoff velocities lowKeep runoff velocities low Divert runoff away from disturbed areasDivert runoff away from disturbed areas Retain sediment on-siteRetain sediment on-site
Grass strips filter soil out of runoff water, as do Grass strips filter soil out of runoff water, as do silt fencessilt fences Establishing VegetationEstablishing Vegetation
Permanent turf is the best cover, but mowing is a problem on steep hillsPermanent turf is the best cover, but mowing is a problem on steep hills HydroseedingHydroseeding- - mixture of water, seed, and chopped hay that is blown on mixture of water, seed, and chopped hay that is blown on
a slope from the side of the roada slope from the side of the road
Calculating Soil LossCalculating Soil Loss The Universal Soil Loss Equation (USLE) The Universal Soil Loss Equation (USLE)
Used to estimate soil lossesUsed to estimate soil losses Predicts soil loss only from small rills and sheet erosionPredicts soil loss only from small rills and sheet erosion
Written As:Written As: A = R K LS C PA = R K LS C P
R = Rainfall factorR = Rainfall factor K = Erodability factorK = Erodability factor – – obtained from soil survey data or obtained from soil survey data or
calculated from USDA Handbook calculated from USDA Handbook 537537
LS = Slope factorLS = Slope factor C = cover and management factor for bare, stripped soilC = cover and management factor for bare, stripped soil
P = support practice factor (usually 1.0; few applicable)P = support practice factor (usually 1.0; few applicable)