Soils Chapters 15 Living in the Environment, 15 th Edition, Miller

B Parent Material Bedrock layer Plow zone Elluviation – move minerals/organic matter Illuviation- accumulate materials due to rain

Detritus is non-living particulate organic material It typically includes: the bodies or fragments of dead organisms, fecal material and colonized by communities of microorganisms which decompose (or remineralize) the material.

Soils: Formation Soil horizonsSoil horizons Soil profileSoil profile HumusHumus O horizon Leaf litter A horizon Topsoil B horizon Subsoil C horizon Parentmaterial Mature soil BedrockBedrock Immature soil Fig , p. 220 Humus= nonliving, finely divided organic matter in soil, derived from microbial decomposition of plant and animal substances.

Soil Properties Infiltration – ground waterInfiltration – ground water enters soil. enters soil. Infiltration – ground waterInfiltration – ground water enters soil. enters soil. Leaching - loss of water-solubleLeaching - loss of water-soluble plant nutrients from the soil plant nutrients from the soil Leaching - loss of water-solubleLeaching - loss of water-soluble plant nutrients from the soil plant nutrients from the soil Porosity/permeability - amount of air spacePorosity/permeability - amount of air space or void space between soil particles. or void space between soil particles. Porosity/permeability - amount of air spacePorosity/permeability - amount of air space or void space between soil particles. or void space between soil particles. Texture – describes particles in soilTexture – describes particles in soil Structure - arrangement of soil separates into units, solids and pore space.Structure - arrangement of soil separates into units, solids and pore space. pH - an indication of the acidity or alkalinity of soil and is measured in pH units.pH - an indication of the acidity or alkalinity of soil and is measured in pH units. Soil pH is defined as the negative logarithm of the hydrogen ion concentration. Soil pH is defined as the negative logarithm of the hydrogen ion concentration. The pH scale goes from 0 to 14 with pH 7 as the neutral point. The pH scale goes from 0 to 14 with pH 7 as the neutral point. pH - an indication of the acidity or alkalinity of soil and is measured in pH units.pH - an indication of the acidity or alkalinity of soil and is measured in pH units. Soil pH is defined as the negative logarithm of the hydrogen ion concentration. Soil pH is defined as the negative logarithm of the hydrogen ion concentration. The pH scale goes from 0 to 14 with pH 7 as the neutral point. The pH scale goes from 0 to 14 with pH 7 as the neutral point. Water High permeabilityLow permeability Fig , p. 224

Ternary diagram

Soil Quality Loam = soil composed mostly of sand and silt, and a smaller amount of clay (about 40%-40%-20% concentration respectively). TextureNutrientInfiltrationWater-HoldingAerationTilthCapacity ClayGoodPoorGoodPoorPoor SiltMediumMediumMediumMediumMedium SandPoorGoodPoorGoodGood Loam MediumMediumMediumMediumMedium Fig b, p. 223 Tilth = suitability of soil for planting crops; tilling land is to mechanical manipulation to improve crop growth.

Soil Chemistry Acidity / Alkalinity – pH Acidity / Alkalinity – pH Major Nutrients Major Nutrients –(N) Nitrogen – green leaves, quality & protein of fruit –(P) Phosphorus (phosphates) – strong roots, increases seed yield and fruit development –(K) Potassium (potash) – color of flowers, quality of fruit, vigorous root growth –

N-P-K (Nitrogen- Phosphorus- Potassium) are the 3 most abundant ingredients listed on EVERY fertilizer label. You will see them on the label as three numbers. Such as: / / The first example, : In 100 pounds of that fertilizer, there would be 30 pounds of available nitrogen, 10 pounds of available phosphorus and 10 pounds of available potassium (potash). The remaining 50 pounds are inert or inactive ingredients.

N = green leaves/ fruit K = fruit quality/ flower color/ vigorous roots P = roots/ seed yield/ fruit development

To turn a lawn green and get it growing, is the fastest and cheapest way to go (NPK, N = green leaves). That is Sulphate of Ammonia. However, to promote a healthy lawn that is more drought- tolerant, you would want the roots (P = roots, K = vigorous roots) to be well developed also. A general purpose lawn fertilizer such as (NPK) would be a far better diet to achieve a truly healthy lawn.

Acidity / Alkalinity – pH Proper pH directly affects the availability of plant food nutrients Proper pH directly affects the availability of plant food nutrients Eastern Pa soil pH 4-6 Eastern Pa soil pH 4-6 Agricultural soil is best if between pH 6 – 8 (except for certain acid loving plants) Agricultural soil is best if between pH 6 – 8 (except for certain acid loving plants) –‘Sour’ if too acidic –‘Sweet’ if too basic Acid rain pH 4.0

Acidity / Alkalinity – pH Too acidic or basic will not Too acidic or basic will not –Allow compounds to dissolve –Allow presence of certain ions If soil is too acidic, add ground limestone If soil is too acidic, add ground limestone If soil is too basic, add organic material like steer manure If soil is too basic, add organic material like steer manure Soil in Appalachian Mountain valley is near limestone deposits Soil in Appalachian Mountain valley is near limestone deposits Normally acidic soil is made more basic by lime = good growing soil, pH 6-8. Normally acidic soil is made more basic by lime = good growing soil, pH 6-8.

Nitrogen Content Importance Importance –Stimulates above ground growth –Produces rich green color –Influences quality and protein content of fruit –A plant’s use of other elements is stimulated by presence of N Taken up by plant as: Taken up by plant as: NH 4 + (ammonium ion) and NH 4 + (ammonium ion) and NO 3 - (nitrate) NO 3 - (nitrate) Replenished naturally by rhizobacteria on legume roots (rhizomes – thick plant Replenished naturally by rhizobacteria on legume roots (rhizomes – thick plant stem, with roots, growing underground) stem, with roots, growing underground) Fertilizer from manure or chemical rxn. Fertilizer from manure or chemical rxn.

Phosphorus for Growth Abundant in Abundant in –Strong root system –Increases seed yield and fruit development –Parts of root involved in water uptake Major role in transfer of energy Major role in transfer of energy Taken up by plant as Taken up by plant as H 2 PO 4 - (dihydrogen phosphate) and H 2 PO 4 - (dihydrogen phosphate) and HPO 4 -2 (hydrogen phosphate) HPO 4 -2 (hydrogen phosphate) Fertilizer is made from rock phosphate Fertilizer is made from rock phosphate

Potassium Content Potash Potash Important in vigor and vitality of plant Important in vigor and vitality of plant –Carries carbohydrates through the plant –Improves color of flowers –Improves quality of fruit –Promotes vigorous root systems –Offsets too much N Found naturally in feldspar and micas Found naturally in feldspar and micas

Justus von Liebig’s Law of Minimum Plant production can be no greater than that level allowed by the growth factor present in the lowest amount relative to the optimum amount for that factor

Soil Formation Soils develop in response to: Climate Climate Living organisms Living organisms Parent Material Parent Material Topography Topography Time Time

Climate Two most important factors that determine climate are: Temperature and Moisture Two most important factors that determine climate are: Temperature and Moisture and they affect: and they affect: –Weathering processes –Microenvironmental conditions for soil organisms –Plant growth –Decomposition rates –Soil pH –Chemical reactions in the soil

Parent Material Refers to the rock and minerals from which the soil derives. Refers to the rock and minerals from which the soil derives. The nature of the parent rock (bottom layer) has a direct effect on the soil texture, chemistry and cycling pathways. The nature of the parent rock (bottom layer) has a direct effect on the soil texture, chemistry and cycling pathways. Parent material may be native or transported to area by wind, water or glacier. Parent material may be native or transported to area by wind, water or glacier.

Topography Physical characteristics of location where soil is formed. Physical characteristics of location where soil is formed. –Drainage –Slope direction –Elevation –Wind exposure Viewed on Macro-scale (valley) Viewed on Macro-scale (valley) or Microscale (soil type in field) or Microscale (soil type in field)

Time After enough time, the soil may reach maturity. After enough time, the soil may reach maturity. –Depends on previous factors –Feedback of biotic and abiotic factors may preserve or erode mature profile.

Destructional -Weathering L andscapes broken down by chemical & physical processes & erosion Physical includes temperature changes (freezing and thawing, thermal expansion), crystal growth, pressure, plant roots, burrowing animals includes temperature changes (freezing and thawing, thermal expansion), crystal growth, pressure, plant roots, burrowing animals causes disintegration of parent material and facilitates chemical weathering causes disintegration of parent material and facilitates chemical weathering Chemical always in water includes hydration, hydrolysis, oxidation, reduction, carbonation and exchange examples : –oxidation of Fe to form limonite, deposited in joints, inhibits groundwater flow –hydrolysis of feldspars to form clay (kaolin) - forms infill for joints

Destructional - Mass wasting Gravitational movement of weathered rock down slope without aid of water or wind (landslips) Gravitational movement of weathered rock down slope without aid of water or wind (landslips) transported material is called: colluvium transported material is called: colluvium often set off by man’s activity often set off by man’s activity can involve very small to immense volumes of material can involve very small to immense volumes of material sliding, toppling, unravelling, slumping sliding, toppling, unravelling, slumping controlled by discontinuities (joints, bedding, schistocity, faults etc) controlled by discontinuities (joints, bedding, schistocity, faults etc)

Destructional - Erosion most significantly by running water Sheet erosion Sheet erosion –by water flowing down valley sides –severe when vegetation removed and geological materials uncemented Stream erosion Stream erosion –materials brought downslope by mass wasting and sheet erosion are transported by streams –erosion by the streams - meanders etc

Destructional - Karsts Forms by dissolution of limestone - limestone is only common rock soluble in water - dissolved carbon dioxide in rain water Forms by dissolution of limestone - limestone is only common rock soluble in water - dissolved carbon dioxide in rain water form highly variable ground conditions form highly variable ground conditions formation of sink holes - when buried leads to surface subsidence formation of sink holes - when buried leads to surface subsidence