1. soil water content 2 thermogravimetric method 6 2. soil water potential 7 2.1 introduction 7 2.2 energy state of soil water 7 2.3 quantitative expression of soil water potential 10 2.4 gravitational potential 10 2.5 osmotic potential 12 2.6 matric potential 13 2.7 external gas pressure potential 16 2.8 hydraulic head 17 3. tensiometer 20 Soil water retention data were fitted to empirical models for estimates of soil matric potential and water content at the hydraulic cutoff. Soil Texture • Sand is largest particle size allowing for more Sand is largest particle size, allowing for more air and water to movement • Clay soils are heavy and hold a lot of water • Loamy soils are intermediate between sand and l d clay – b th t h ldi it d both water holding capacity and fertility Importance of Soil Provides nutrients Recycles/filters water Stores water Soil is the basis of life on Earth…why do you think? Sometimes called by other names. Soil water retention curve. Usually determined based on empirical data. Soil ppt 1. Usually soil volumetric water content is used. That is, when all pores are filled with water. Soil moisture release curve. 6 Major components of soil Eroded rock Mineral nutrients Decaying organic matter Water Air Living organisms 3. Can work at very low water potentials (as low as –1500 kPa) Useful for clays Sensitive to temperature and … The relationship between soil matric potential and soil water content “matric suction” = - soil matric potential. SMM – How it Works • Step 7: • Find equation from your moisture release curve Curve A Sandy Soil: Soil Water Potential = 5343 x Soil Water Content-1.852 Curve B Clay Soil: Soil Water Potential = 6x107 x Soil Water Content-4.228. In soil, the reference state is the energy level of water in the soil at saturation. Soil moisture characteristic curve. Water Potential Water potential Tendency of a solution to take up water Tendency of water to diffuse from one area to another (psi) Water potential Two components to ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 757a10-OWNkZ Soil Porosity and Permeability • Porosity is the total amount of pore space in the soil (30 to 60%) – Affects the storage of air and water – Affects the rate of movement of air and water • Permeability is the ease in which water, air, and plant roots move through the soil – Ease of air, water and root movement – Affects rate of water intake and drainage At this point soil water potential (Ψ) is nominally zero (~0). APES 2. “The water potential concept replaces the arbitrary categorization that prevailed in the early stages of the development of soil physics and that purported to recognize and classify different forms of soil water, such as, gravitational water, capillary water, hygroscopic water” (Hillel, 1998). In most cases, however, soil water potential (Ψ)is less than zero. Resistance block: Deriving soil water potential from the electrical resistance of a block of porous material buried in the soil and in equilibrium in water suction with the soil. This is indicated by giving soil water potential (Ψ) a … Electrolyte ‐Soil or water (any conductive environment) adjacent to –and containing both the anode and the cathode ... ¾A structure‐to‐soil potential is read and recorded ... Microsoft PowerPoint - 2 C&C Iozzo Corrosion Cathodic Protection.pptx Author: SMM – How it Works • Step 8: • Enter equation into the SMM software as a script