Soils Evaluation - Crop and Soil Science - Lecture Slides, Slides of Botany and Agronomy

Download Soils Evaluation - Crop and Soil Science - Lecture Slides and more Slides Botany and Agronomy in PDF only on Docsity! Soils Evaluation Docsity.com What good is it? • teaches the practical application of the Soil Conservation Service soil classification system and related land management practices. Docsity.com Georgia Land Capabilities • Class VII These soils have very severe limitations and their use is restricted to forestry and wildlife. Docsity.com FACTORS AFFECTING LAND CLASS • Slope • Topsoil thickness • Erosion • Topsoil texture • Permeability of the subsoil • Drainage • Effective depth Docsity.com Slope • Slope refers to the steepness of the field. It is determined by the amount of fall in feet per 100 feet and is expressed in percent. If measured over a 100 foot distance, it is easy to convert the fall in feet to percent. Example: if the fall is 12 feet over a distance of 100 feet (12 divided by 100) the slope is 12% Docsity.com SOIL FACTORS Best Land Class For Slope (South Georgia) Catagories of slope % of slope Best Land class Nearly Level 0-2 % I Very Gently 2-5% II Gentle 5-8% III Sloping 8-12% IV Strongly Sloping 12-17% V! Steep Over 17% VII Very Steep Not Applicable VII Docsity.com Topsoil thickness • 1. Extremely thick -- over 40 inches • 2. Very thick -- 20 to 40 inches • 3. Thick -- 10 to 20 inches • 4. Moderate -- 5 to 10 inches • 5. Thin -- less than 5 inches Docsity.com Erosion • 1. None to slight - less than 25% eroded • 2. Moderate - 25 to 75% eroded • 3. Severe - Over 75% eroded Docsity.com Topsoil Textures • Medium - A medium textured soil is a mixture of sand, silt and clay particles. It is between fine and coarse. The ball will show some finger marks and hold its shape. A short thick ribbon can be formed. Docsity.com Topsoil Textures • Coarse - Coarse textured soils are made up of mostly sand particles. Sand feels gritty and particles are large enough to be easily seen. The ball breaks in your hand and almost no ribbon can be formed. Docsity.com Permeability of the Subsoil • Permeability is the ability of air and water to move through the subsoil. Permeable soils (rapid) are often described as "loose" and impermeable soils (slow) as "tight." Docsity.com Drainage • 1. Excessively drained -- Coarse textured, sandy material that continues to depths of more than 40 inches. • 2. Well-drained -- No gray mottles found in top 30 inches of profile. • 3. Moderately well- drained -- No gray mottles found in top 20 inches of profile Docsity.com Drainage • 4. Somewhat poorly drained -- No gray mottles found in top 10 inches of profile. • 5. Poorly drained -- Gray matrix or gray mottles found in top 10 inches of profile. Soil may be gray completely to the surface. • 6. Very wet -- Surface water remains for extended periods. Docsity.com Effective Depth • Effective Depth is that depth to which plant roots can easily penetrate. Docsity.com