Soil Composition 2 1/13/12

What are the soil textures? Table 1. The Size of Sand, Silt and Clay NameParticle Diameter Clay below millimeters Silt to 0.05 millimeters Very fine sand Fine sand Medium sand Coarse sand Very coarse sand 0.05 to 0.10 millimeters 0.10 to 0.25 millimeters 0.25 to 0.5 millimeters 0.5 to 1.0 millimeters 1.0 to 2.0 millimeters Gravel 2.0 to 75.0 millimeters Rock greater than 75.0 millimeters (~2")

What some chemical soil tests? pH Salinity Organic content – C, H, O mostly Ion Exchange

What do physical tests look for? Permeability Porosity Texture Moisture content Particle density Soil structure/clumping Percolation rate Capillary of soil Soil compaction Soil profile Analysis Color

How can we ecologically restore soil fertility? Topsoil conservation + fertilizers – Crop rotation – Organic fertilizers: animal manure, green manure, compost – Manufactured inorganic fertilizers contain macronutrients (i.e. N, P, K)

How can we reduce soil salinization? Prevention: – reduce irrigation – switch to salt tolerant crops Clean up: – flush soil ($, wastes water), – stop growing crops for 2-5 years – Install underground drainage systems ($)

How can we reduce desertification? Slow Global warming/climate change Reduce… – population growth – overgrazing – deforestation – destructive forms of planting – irrigation – mining.

How can we reduce soil erosion? Terracing Contour planning Strip cropping Alley Cropping/agroforestry Windbreaks/shelter belts Low till or no till agriculture Don’t overgraze rangelands