CH. 4 First Part
CH. 4 First Part PSS 3303
Popular in Soils
Popular in plant and soil sciences
This 4 page Class Notes was uploaded by Payton Gilmore on Tuesday October 4, 2016. The Class Notes belongs to PSS 3303 at Mississippi State University taught by Dr. Jac J. Varco in Fall 2016. Since its upload, it has received 3 views. For similar materials see Soils in plant and soil sciences at Mississippi State University.
Reviews for CH. 4 First Part
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/04/16
CH. 4 PHYSICAL PROPERTIES: Soil Productivity Water holding capacity and drainage Construction suitability SOIL TEXTURE: Fine earth fraction, excludes pebbles, rocks, etc. The diameter of a particle determines which of the soil separates it is. The USDA classification is as follows: FIG. 4.1, PG. 98 IN BOOK Soils are approximately 45% by volume mineral matter. Relative proportions of sand, silt, and clay (soil separates) comprise or determine the texture of a soil. SEE FIG. 4.2, PG. 99 Decreasing particle sizeSurface area increases. Adsorption of water, gases, and nutrients and a greater attraction of particles to each other greater. (also faster weather, ^ swelling, plasticity, and cohesion) Sand and Silt Particles don’t stick together FIG. 4.3 PG. 99 SOIL TEXTURE GENERALIZATIONS: Clay Soils o Hold > H2O than coarser textures o Hold > nutrients than silt and sand o Adsorb > gases such as NH3 o Develop > structure Sandy Soils o > permeability to air and water o Lower water and nutrients o Lower in organic matter o Less developed structure SOIL TEXTURE TRIANGLE- 12 TEXTURAL CLASSES SEE FIG. 4.4, PG. 101 Loam best soils to garden o Less clay Soybeans are grown on clay Cotton- silt loam SOIL STRUCTURE Arrangement of individual soil particles into larger units. Units of soil structure- peds or aggregates; natural groups of soil separates, occur and persist within the soil o Many soils in the Delta have lost OM and SS is down CLASSIFICATION OF SOIL STRUCTURE A. Grade 1. Weak- aggregates too weak to remain intact upon removal 2. Moderate- remain intact when removed from soil, but can be crushed 3. Strong- visible in undisturbed soil, break into whole peds when removed from profile. Difficutly in crushing. 4. Structure-less- no observable aggregation, no natural planes of weakness. - Single grain in non-coherent 2 - Massive if coherent- commonly found in C horizons/parent material B.Class o Size of ped or aggregate a. Fine b. Medium c. Coarse C.Type o Shape of peds, natural planes of weakness 1. Spehrical- round in shape - Granular: porous - Crumb: very pourous o Good aeration, drainage, and highly desirable for plant growth. A horizons especially under grassland conditions. 2. Platy-peds with greater horizontal dimensions than vertical - Usually found in A E horizons. Related to parent material, frost action, water table fluctuations, and horizontal water movement. 3. Prism-like- dimensions greater in the vertical than horizontal - Prismatic: square tops - Columnar: rounded tops o B horizons well-developed soils. Most common in aridisols. Fragipans of MS. 4. Block-like- equal size in 3D - Angular blocky - Subangular blocky 3 o Common in B horizons - Ex. Strong, medium, subangular blocky Fig. 4.8, pg. 106 GENESIS OF SOIL STRUCTURE 1. Physical processes-orientation of soil particles - Wetting and drying - Freezing and thawing - Root action - Action of soil organisms - Textural influences 2. Biological - Plant root exudates - Microbial by-products - earthworm activity To learn more and get OneNote, visit www.onenote.com. 4
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'