2.Soil morphology set the stage for understanding soil physical and chemical pro
ID: 120862 • Letter: 2
Question
2.Soil morphology set the stage for understanding soil physical and chemical properties in what ways?
a. Parent material, weathered to produce soil, varies in particle size and chemical characteristics due to mode of deposition and rock/mineral composition. Explain each characteristic that are provided and the impacted they have on each other?
b. Mode of deposition affects soil texture; draw a diagram of the various parent materials (e.g., colluvium, flood plain, till, loess, etc.).
c. The quality of that material is influenced by elemental composition of primary and secondary minerals (e.g. biotite, hematite, calcite, etc.) what are the different between primary and secondary minerals? that occur in the rocks (e.g. granite, gneiss, shale, limestone, etc.) comprising the parent material.
d. Soil texture, in turn, influences soil organic matter, both profoundly influencing soil structure. describe this processes?How this impact bulk density, total pore space, and pore size distribution?
e. Landscape position combined with soil physical properties influence movement and storage of water, a concept that is statically captured by soil drainage class and dynamically captured by hydraulic conductivity and the soil moisture characteristic. Explain this process in details?
f. How this influences soil aeration, thermal conductivity, and temperature, strongly affecting biological productivity. Landscape position and soil properties, combined with management all influence erosion potential; BMPs minimize soil degradation during management operations.
Explanation / Answer
2.a) Soil is formed from the weathered basement rocks. Parent materials are classified on the basis of gravity, streams, oceans, lakes, ice and wind and they are known as colluvial, alluvial, marine, lacustrine, glacial and eolian respectively. Soil characteristics, particularly acidity is influenced by the mineral content of leaves, limbs, stems of vegetation. For example, Pines tend to be low in calcium, magnesium, potassium reducing nutrient cyclining compared to deciduous trees.
b)
c) Primary minerals are minerals that are formed in situ or in the same condition at which magma solidifies whereas secondary minerals are formed by weathering or hydrothermal alteration of primary minerals. So both of these minerlas ecffect the soil composition. Secondary minerals form clay or silt fractions. Most soil particles are composed of silicates, on the other hand non-silicate soils are formed of oxides, carbonates and sulfates. If considering rocks, then igneous rocks like granites are primary rocks and sedimentary and metamorphic rocks are formed by weathering or secondary processes, so these are secondary rocks.
d) Both soil texture and soil organic matter influences soil structure. Arrangement of primary soil particles and other soil materials into discrete aggregates is called soil structure. Based on these soil can be classified as having good or poor structure. Structure units are called peds. Different ped shapes like blocky, columnar, prismatic, single-grained, massive, granular are found. The size of peds are described as fine, medium and coarse.Soils with good structure, the pore space between the peds will be larger and facilitates water and air movement. On the other hand, clayey with poor structure restrict water and air movement. Soil bulk density is the ratio of weight of dry soil to the volume of dry soil.Organic soils have very low bulk density and clayey soils have higher bulk density. Soil porosity is the percentage ratio of bulk density and particle density. The average soil porosity is 50%.
Parent materials Soil textures Alluvial The sediments are composed of sand gravel with a little proportion of silt and clay. The sediements are well sorted. Ex- alluvial fans, delta, channel deposits. Eolian Thsese are formed by wind action. Soil is composed of medium to fine sand and coarse silt particles, show internal structures like cross lamination. Ex- dunes. Colluvial Due to gravity-induced movement well stratified, non-sorted to poorly sorted clay to boulder-sized particles form the soil. Ex- creep, solifluction. Fluvioglacial Materials that are moved by glaciers and subsequently sorted and deposited by streams, form stratified deposits. Ex- kames. Lacustrine stratified, moderate to well sorted sand, silt, clay particles deposited on lake bed. Residual Unconsolidated, weathered or partly weathered materials that are accumulated by in situ disintegration of bedrock.Related Questions
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