FOR 232 1st Edition Lecture 4Outline of Last Lecture I. EcosystemII. Point Sur, CAIII. Light and TemperatureIV. TemperatureV. Water and HumidityVI. LinkageOutline of Current Lecture: Soils or the biogeochemical membrane (chapter 4)I. System Maintenance (fluxes)II. Six requirements for Plant GrowthIII. Factors of Soil FormationIV. What constrains fluxes?V. Dynamic 4-phase systemVI. Texture and structure VII. Pore size distributionVIII. Site qualityIX. Topography X. Morphological ‘footprint’ of seasonally high water table?XI. Soil Drainage classesXII. Traffic= Affects soil physical propertiesXIII. Affecting flux of water XIV. Affecting flux of gas and aerationXV. Affecting flux of energyCurrent LectureI. System Maintenance:a. Energy, water and gas fluxes= constrain Biota (living stuff)II. Six requirements for Plant growth:a. Lightb. Favorable temperaturec. Waterd. Aeratione. Absence of Toxic Substancesf. Nutrient Elements (18 essential)III. Factors of soil formation (5 of them)a. Climate These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Parent material c. Topography d. Organismse. Time i. Side note: people have the greatest impact on soilIV. What constrains the fluxes?a. Soil physical properties i. Textureii. Coloriii. Structureb. Dynamic 4-phase system:i. Air (20 to 30%)ii. Water (20 to 30%)iii. Mineral (45%)iv. Organic material (5%)V. Texture and Structurea. Determine pore size/ configurationb. Micro and Macro systemsc. Soil Texture: relative proportion of primary particles:i. Sand 2.0-0.05 mmii. Silt 0.05- 0.002 mmiii. Clay < 0.002 mmiv. Anything bigger = rocks and pebblesd. Soil Structure: aggregation of 1° particles into 2° units VI. Pore Size Distributiona. Macropores: large diameter poresi. Water flows freely if drainage is unimpededii. 0.08 to 5+ mm diameterb. Micropores: small diameter poresi. Hold water against the force of gravityii. 0.03 to 0.08 mm diameter (mesopores)c. Which are reduced by destruction of structure?i. MacroporesVII. Site Quality:a. A relative measure of the vegetation production capacity of a site for a given purposeb. Produce amount/ unit area/ time periodVIII. Topographya. Convex: water sheddingb. Concave: water collecting c. Greater slope= greater water movement d. Catena: group of soilsi. Similar parent materialii. Differ in class due to topographic position (slope)IX. Morphological ‘footprint’ of seasonally high water table?a. Redoxymorphic features aka mottling X. Soil drainage classes: vary with landscape positiona. EWD= Excessively well-drained: deep sands or thin soils on ridgetops with low water storage and rapid movement b. SED= Somewhat excessively drained: loam texture over coarse texturec. WD= Well drained: no mottling in solum; convex upper sloped. MWD= Moderately well drained: mottling in lower solum; convex upper slopee. SPD= Somewhat poorly drained: mottling in upper solum; linear, slightly concave lower slopef. PD= Poorly drained: mottling close to soil surface; concave lower slopeg. VPD= Very poorly drained: standing water tableXI. Traffic= Affects soil physical propertiesa. Traffic could destroy soil structure i. Most severe when soils are wetii. Recovery may require years to decades iii. Rearrangement and packing in sandy soilsiv. Minimize disturbance (use BMPs)XII. Affecting flux of water a. Waterb. Overland flowXIII. Affecting flux of gas and aerationa. Well aerated soili. Gas exchange sufficiently rapid to: replenish O2 and prevent buildup of CO2XIV. Affecting flux of energya. Soil thermal properties i. Specific heat: ration of the amount of heat energy required to raise the temperature of a substance (soil) 1°C compared to that required to that required for the same volume of waterii. 1.0 cal/g (kcal/kg) for water {4.19 J/g}iii. 0.2 cal/g dry soil {0.8 J/g}b. Heat of Vaporization: the amount of energy required to vaporize wateri. 540 kcal/kg [2.257 MJ/ kg]ii. Heat transfer in Soil: Qh= K(ΔT)/xiii. Qh quantity of heat transferred cross unit x-section per unit time (thermalflux)iv. ΔT= T1 – T2 temperature gradient over distance xv. K thermal conductivity influenced by:1. Soil moisture2. Organic matter content3. Soil texture4. Bulk