Louisiana Yards and Neighborhoods

1. www.lsuagcenter.com/lyn Louisiana Yards and Neighborhoods Water Efficiently!

2. Water efficiently! • Plants • Soils • Systems • Mechanics

3. Plants • Plant water needs • Water movement • Evaporation and transpiration • Evapotranspiration • ET-LAIS (EvapoTransporation values from Louisiana Agriclimatic Information System) • Temperature vs. relative humidity

4. 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

5. Water Movement

6. 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.

7. Evapotranspiration

8. 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/potentialUseOfETOData.asp

9. Temperature vs. Relative Humidity

10. Soil (or Media) • Porosity • Permeability • Field capacity • Wilting point • Available water holding capacity • Soil texture • Water intake rate and depth • Compaction

11. 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.

12. 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)

13. 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%.

14. 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%

15. 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

18. 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.

19. Systems • Garden furrow irrigation • Lawn sprinkler irrigation • Drip or micro irrigation

20. 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

21. 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.

22. 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

23. Mechanics • Basics • Flow restrictions • Schedule 40 PVC pipe flow rates • Drainage

24. 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.

25. Mechanics – Basics(continued) • Electronic controllers available to automate system. • Filtration is essential for drip or micro systems. • Water quality: check pH, salts, sodium, iron, manganese, calcium. • Chemigation is possible. • Maintenance is essential.

26. 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.

27. Mechanics – Schedule 40 PVC Pipe Flow Rates

28. 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.

29. www.lsuagcenter.com/lyn Louisiana Yards and Neighborhoods Water Efficiently!