Soil ScienceLand, then, is not merely soil; it is a fountain of energy flowing through a circuit of soils, plants, and animals. - Aldo Leopold, A Sand County Almanac, 1949

The Rock CycleSEDIMENTMeltCool & HardenHeat & PressureErode & WeatherMAGMAErode & WeatherCompaction & CementationMeltErode & WeatherMeltHeat & Pressure

What is SOIL????The relatively thin surface layer of the Earths crust consisting of mineral and organic matter.Soil is not DIRT!

Q: Whats the difference between soil and dirt?

Location, location, location! Dirt is found under your nail, soil is found beneath your feet

The 5 Soil-Forming Factorsclimate (water, wind, temperature)biology (macro- and microorganisms, plants)relief (topography)parent material (rocks/minerals)time Which is the MOST important??CLIMATE!!!Formed from parent material (bedrock) thats slowly broken down through weathering processes.

What is Soil?How would you describe soil?Color TextureTexture

Why the color?Hematite: redGoethite: yellowish brownFerrihydrite: reddish brownCalcite: off whitehttp://www.pitt.eduQuartz: whiteOrganic matter: blackhttp://www.organicgardeninfo.com

Did you know ??????There are more than 20,000 different soil types in the United States

Soil Color Variation

Soil CompositionWater (~25%)Air (~25%)Mineral(~45%)Humus (~5%)Mineral matter comes from parent material

Air & Water percents are interchangeable

Humus is organic matter!

Soil Composition continuedMineral MatterProvides nutrient minerals for plantsProvides pore space for water & air

Older soils are:More weatheredLower in certain essential nutrient mineralsHumus: black/dark brown organic material remaining after decompositionLeaf litter, animal dung, & decaying organismsIncreases the soils water-holding capacity by acting like a sponge

POROSITY = amt of soil pore spaces

Pore spaces occupy ~50% of a soils volumeFilled with varying proportions of soil water and soil air

Soil Air contains the same gases as atmospheric air, but in different proportions.More CO2 and less O2 (from organism respiration)Some bacteria need nitrogen (why??)The CO2 can accelerate weatheringCO2 + H2O H2CO3 (carbonic acid)PorositySoil Composition continued

Soil Composition continuedAs water infiltrates the soil, it can carry dissolved materials with it.

Leaching: Removal of dissolved materials from the soil by water percolating downward

Illuviation: Deposition of leached material in lower layersSome substances completely leach out of the soil because theyre so soluble that they migrate right down to the groundwater.

Observe this SOIL PROFILE through soilSoil layers are horizons and assigned lettersO: Organic material (may be absent)A: Topsoil - Organic material & mineral grainsE: Leached zone (may be absent)B: Subsoil rich in clay, iron, aluminumC: Weathered bedrockR: Bedrock (parent material)

A horizon: organic coatingsB horizon: Iron coatingsC horizon: little coatingSoil Color by Horizonhttp://nesoil.comFun Fact: It takes 100 to 600 years to form an inch of topsoil.

Soil Color Variation by GeographyRed soils: Southeast US

Soil Color Variation by GeographyBrown/black soils: Midwest

http://www.scienceclarified.comSoil Color Variation by GeographyWhite (gypsum) sands: New Mexico

Soil OrganismsEx: bacteria, fungi, algae, microscopic worms, protozoa, plant roots, insects, earthworms, moles, snakes, groundhogs, etc.

Soil organisms provide several Ecosystem Services (important environmental functions).maintaining soil fertilitypreventing soil erosionbreaking down toxic materialscleansing wateraffecting atmospheric composition

Earthworms & Ants: Cycle mineralsAerate the soilDecomposing corpses contribute organic matterAssist plants in reproduction by burying seeds

MycorrhizaeSymbiotic relationship between fungi and the roots of vascular plantsFungus absorbs nutrients from the soil, and provides it for the plant.Plant produces food (photosynthesis), and provides it for the fungus.

Dr. Greg Pillar, Queens College

Physical Soil PropertiesPHYSICAL properties:Texture (%sand, silt, clay)Porosity & PermeabilityIonic Charge

Texture is determined by its % sand, silt, and clay.

Texture determines the type of soil, and the soils properties.

Physical Property: TextureLoam: ideal for agricultural soil

Soil Componentshttp://school.discoveryeducation.comQ: What did the shy pebble say to the big rock?

A. Do you think Ill ever be a little boulder?

Fine Texture - Clayhttps://www.soils.org/lessons

Course Texture - Sandhttps://www.soils.org/lessons

Soil TextureThe relative portions of sand, silt, and clay-sized particlesSand: 2.0 0.05 mmSilt: 0.05 0.002 mmClay: < 0.002 mm

BSoil Texture Diagram PracticeWhat type of soil has:20% clay, 40% silt, 40% sand40% clay, 10% silt, 50% sand30% clay, 60% silt, 10% sand

Find the % of each particle at:ABCAC60%clay, 20%silt, 20%sand30%clay, 40%silt, 30%sand10%clay, 30%silt, 60%sand(1) Loam(2) Sandy clay(3) Silty clay loam

Why is Soil Texture Important?

PropertySandSiltClayWater holdingLowMed-highHighAerationGoodMedPoorNutrient supplyingPoorMed-highHighPollutant FilteringLowMedHigh

Physical: Porosity & Permeability again Think it is important??Definition?amt of soil pore spacesPorosityPermeabilityDefinition?ability of water to percolate through

____ porosity = ____ permeability

Physical: Ionic ChargeSoil minerals are often present as ions.Minerals ions are either positively or negatively charged.Clay particles have mostly negative charges on their outer surfaces.Positively charged mineral ions are attracted to the soil particles and are held for plant use.potassium K+ and magnesium Mg2+Negatively charged mineral ions are repelled by the soil particles and are washed away from roots.nitrate NO3-

Physical Characteristics (review)Why would 100% sand be undesirable for plants?Why would 100% clay be undesirable for plants?

Answer SAND / SILT / CLAY for the following:A soil with a lot of _____ would have good drainage, but poor nutrient-holding characteristics.A soil with a lot of _____ would have poor drainage, but good nutrient-holding characteristics.A soil with a lot of _____ would have low porosity.A soil with a lot of _____ would have high permeability.

Chemical Property: AcidityMost soil pH is 4-8. Plants are happiest at 6-7. Plants are affected by soil pH.(1) The solubility of certain nutrient minerals varies with differences in pHLow pH = Al & Mn are more soluble, and can be absorbed in toxic amounts.High pH = some salts are less soluble, and are less available to the plants.(2) Soil pH affects the leaching of nutrient minerals.Acidic soil = positively charged ions are less soluble and are unavailable for plants.

Soil Conditioners (Lime)CaCO3 or MgCO3Soil amendment / conditioner not a fertilizer!Important functions:Corrects soil acidityAdds important plant nutrients Ca & MgReduces solubility & toxicity of certain elements in the soil Al, Mn, FeThis toxicity could reduce plant growth under acid conditions.Promotes availability of major plant nutrients. Zn, Cu, PIncreases bacterial activity & mutualistic relationships.http://www.wvu.edu/~Agexten/hortcult/turf/liming.htm

Soil Conditioners (Compost)Decayed organic matterReplaces some nutrientsImproves soil structureThe soil becomes more porous, increasing air circulation and the ability of the soil to absorb and hold moisture.Makes the soil more spongy!http://www.wvu.edu/~Agexten/hortcult/turf/liming.htm

Soil supports lifehttp://www.Istockphoto.com L. Clarke and Corbis, 2008Why is Soil Important?Fun Fact: 1 teaspoon of good soil contains more than 1 million bacteria!Fun Fact: There are more living organisms in a cubic foot of soil then all of China!Fun Fact: There are more living organisms in a cubic foot of soil then all of China!Dr. Greg Pillar, Queens College

Soil stores important nutrientshttp://www.lesco.com/Phosphorus (P)Nitrogen (N)Potassium (K)Calcium (Ca)Magnesium (Mg)

Dr. Greg Pillar, Queens College

Soil Holds WaterDr. Greg Pillar, Queens College

Soil provides support for buildingshttp://www.pbase.comDr. Greg Pillar, Queens College

SoilSoil filters, buffers, detoxifies.http://extension.missouri.eduDr. Greg Pillar, Queens College

Inputs/OutputsAre these Soil Inputs or Soil Outputs?Mass Movements (landslides, etc)PrecipitationParent MaterialLeachingInfiltrationUptake by PlantsOrganic MatterEnergyIIIIOIOO

Transfers/TransformationsRecall: Transfers simply MOVE things they reorganize the soil!Transformations CHANGE thingsthey alter the soils makeup in some way.

Are these Soil Transfers or Transformations?DecompositionErosionDepositionWeatheringNutrient Cyclingtransfertransfertransformationtransformationtransformation

Soil PollutionPart II

Soil Pollution= any physical or chemical change in soil that adversely affects the health of plants and other organisms living in and on it.

Many soil pollutantsARE MOBILE! move into groundwater, surface water, or airARE PERSISTENT! seep into tiny cracks called micropores and adhere to the soil particlesCOME FROM FERTILIZERS / PESTICIDES! CAN ACCUMULATE!

Sustainable Agriculture practices can helpmore on this later

Salinization of Irrigated SoilIrrigation water soaks through the soil area where the plant roots grow, adding to the existing water. The additional irrigation water causes the underground water-table to rise, bringing salt to the surface. When the irrigated area dries & the underground water table recedes, salt is left on the surface soil. Each time the area is irrigated this salinity process is repeated. ALL IRRIGATION WATER CONTAINS SOME DISSOLVED SALTS.

Salinization of Irrigated SoilExtra water flows through the soil, mixing w/ salt underground, and bringing it to the surface.This is in Australia occurred not from irrigation, but from lack of water-loving plants.Irrigation salinization is basically the same concept, and the ground would look just like this.

Effects of Salinized Soil on PlantsNormally, the water concentration inside plant cells is lower than that in the soil resulting in a net movement of water into the root cell.

When soil contains a high amount of salt, its relative water concentration can be lower than the water concentration inside cells. This causes water to move out of the roots into the soil, even when the soil is wet.

Soil RemediationUntil recently, the only way to remove soil contaminants was to

Why is this a bad thing to do??Impractical, kills all beneficial organisms, creates waste, expensiveDIG IT UP& INCINERATE IT!

Soil Remediation TechniquesDilutionAdd lots of water; leach out pollutantsVapor extractionInject air into soil to remove volatile organic compoundsBioremediationUse microorganisms to degrade organic contaminants (oil, sludge)PhytoremediationUse plants to absorb contaminants such as salts or heavy metals.

Extraction wellPollutant low sorption potential = not attracted to soil easily washed awayPollutant high sorption potential = not easily washedWaterDILUTION: Pump & Treat / Soil WashingGROUND LEVEL

But whats the problem here?Source Identification and Removal !!!!How can this problem be fixed???GROUND LEVEL

Bioremediation (Bioventing)12 - 32

15.06.bActivities that Threaten SoilRemoving vegetationOvergrazingSoil contaminationErosion Control

Agricultural: 10% of the worlds best agricultural land damaged due to soil erosion and overuse over last 50 years.contour plowingno-till agriculture (no plowing)terracing slopescrop rotation - fallowPreventing Soil Erosion

*******************************NOTES Overgrazing: Namibia, southern AfricaClear cutting: Mount Rainer, WashingtonTerracing to prevent erosion: PeruSoil contamination (salt build up and pesticides): Colorado

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