Louisiana Yards and Neighborhoods www. lsuagcenter. com/lyn Water Efficiently!
Water efficiently! • Plants • Soils • Systems • Mechanics
Plants • Plant water needs • Water movement • Evaporation and transpiration • Evapotranspiration • ET-LAIS (Evapo. Transporation values from Louisiana Agriclimatic Information System) • Temperature vs. relative humidity
Plant Water Needs • Germination • Vegetative phase • Reproductive phase • Transpiration cools plant, provides suction to pull water and nutrients from the soil into roots • Plants have differing water needs
Water Movement
Evaporation and Transpiration • Evaporation dominates vegetative phase of growth and increases with increased frequency of irrigation. • Transpiration dominates reproductive phase of growth and is affected by plant density, mono-culture/mixed bed, exposure to sun, wind and built environment.
Evapotranspiration
ET-LAIS • To find ET values at LAIS weather stations: http: //www. lsuagcenter. com/weather/Etotabledata. asp • A description of ET use: http: //www. lsuagcenter. com/weather/potential. Use. Of. ETOData. asp
Temperature vs. Relative Humidity
Soil (or Media) • Porosity • Permeability • Field capacity • Wilting point • Available water holding capacity • Soil texture • Water intake rate and depth • Compaction
Soil – Porosity • Volume of pore space within a given volume of soil (%). • Pore spaces are available for air and/or water and/or roots. • When soil is saturated with water, there is no room for air. • Roots (of most plants) will not grow into water.
Soil – Permeability • How fast can water move into/through soil (inches/hour)? • Higher in dry soil, lower in wet soil • Higher in soils with larger pore spaces (sands, loams) • Lower in soils with smaller pore spaces (silts, clays)
Soil – Field Capacity • Moisture content of soil 24 -48 hours after saturation. • Gravity causes “free” water to drain down below root zone. • Air moves into pore spaces as water drains. • Water is readily available to plant. • Moisture content at field capacity may be: sand – 10%, silt loam – 20%, clay – 50%.
Soil - Wilting Point • Moisture content of soil after plant has removed all the water it can. • Moisture content at wilting point may be: – Sand 1% – Silt loam 5% – Clay 25%
Soil – Available Water-holding Capacity • Available water holding capacity (AWHC) = field capacity minus wilting point. • AWHC for sand may be 10%-1% = 9%, or. 09 x 12 inches/foot = 1. 08 inches/foot. • AWHC for silt loam may be 20%-5% = 15%, or. 15 x 12 inches/foot = 1. 8 inches/foot. • AWHC for clay may be 50%- 35% = 15%, or. 15 x 12 inches/foot = 1. 8 inches/foot
Soil – Compaction • Compaction reduces both porosity and permeability. • Compaction can be increased by traffic, tillage and chemical changes such as adding sodium or calcium. • Soil compacts easily when wet.
Systems • Garden furrow irrigation • Lawn sprinkler irrigation • Drip or micro irrigation
Systems – Garden Furrow Irrigation • High losses of water to evaporation and percolation below root zone • Low distribution uniformity as water travels down the row • Short-term saturation of soil pore spaces • Wet furrows after irrigation
Systems – Lawn Sprinkler Irrigation • If properly designed, installed, maintained and operated, sprinklers provide most efficient means for uniform irrigation of lawns. • Higher pressure requirements: 30 -60 pounds per square inch (psi) than furrow or drip irrigation. • Easily automated.
Systems – Drip/Micro Irrigation • Facilitates daily or more frequent irrigation to reduce plant moisture stress • Low pressure requirements: 10 -15 pounds per square inch (psi) • Low flow rates: gallons per hour (gph) instead of gallons per minute (gpm) • Easily modified as needed
Mechanics • Basics • Flow restrictions • Schedule 40 PVC pipe flow rates • Drainage
Mechanics – Basics • Flow rate: gallons/minute (gpm) or inches/day. • Pressure: pounds/square inch (psi). • Pressure is lost from pipe friction and other restrictions to flow. • Freeze protection: exposed PVC is at risk below 20 degrees. • Backflow protection is essential.
Mechanics – Basics (continued) • Electronic controllers available to automate system. • Filtration is essential for drip or micro systems. • Water quality: check p. H, salts, sodium, iron, manganese, calcium. • Chemigation is possible. • Maintenance is essential.
Mechanics – Flow Restrictions • Water flowing through a pipe creates friction, which reduces pressure. • Changing water flow direction reduces pressure. • The labor to install a 1 -inch pipe is the same as for a ¾-inch pipe, but friction losses are greatly reduced.
Mechanics – Schedule 40 PVC Pipe Flow Rates Diameter (in) ½ ¾ 1 1¼ 1½ 2 Flow (gpm) 4 8 12 22 30 50 Velocity (ft/sec) 4. 2 4. 8 4. 4 4. 7 4. 8 Loss (psi/100’) 5. 6 5. 1 3. 4 2. 7 2. 3 1. 7
Mechanics – Drainage • Design landscape to drain. • Surface drainage is the only practical solution. • Subsurface drainage is absolutely the last resort. • Divert drainage coming onto landscape from your roof, driveway or your neighbor’s yard.
Louisiana Yards and Neighborhoods www. lsuagcenter. com/lyn Water Efficiently!
Скачать презентацию Louisiana Yards and Neighborhoods www lsuagcenter com lyn Water
1d5e00e70b528aab8911fd510429d9f1.ppt