j.g. mexal a/h 100
DESCRIPTION
Water & Transpiration or Water, water everywhere and all the boards did shrink. Water, water everywhere and not a drop to drink. J.G. Mexal A/H 100. Potential Evapotranspiration/ Las Cruces. PET = evaporation + transpiration from a crop under non-stressed conditions - PowerPoint PPT PresentationTRANSCRIPT
Water & Transpirationor
Water, water everywhere and all the boards did shrink. Water, water everywhere and not a drop to drink.
J.G. Mexal
A/H 100
PET = evaporation + transpiration from a crop under non-stressed conditions
• Adjusted to a ‘reference crop’ (grass)
• Crop coefficient (kC) = ETC / ETO
• Function of T, RH, season, leaf area, shading, crop species, soil moisture
Potential Evapotranspiration/ Las Cruces
Las Cruces Potential Evapotranspiration
0
0.1
0.2
0.3
0.4
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
PET (in/d)
Water (in/d)
Trees and Water… Turfgrass Actual Water Use / Farmington NM/ D. Smeal
Warm Season Cool Season
Trees and Water… Turfgrass Actual Water Use/ Farmington NM /D. Smeal
.25
.15
.05
100 300200
Julian Days
ET (in/d)
Cool Season
Warm Season
Late, Warm Season
Apr Jul Oct
Trees and Water… How often should new trees be watered?
0
1
2
3
4
5
6
0 20 40 60 80 100
#5#1524" box
Time since transplanting (d)
Days without water (no.)
Irrigation Scheduling-nonstressed
Fancy formula:• PAW = AWC x MAD x RZ• Sooo,
Plant Available Water =
soil Available Water Content x Maximum Allowable Depletion x Root Zone depth
0123456789
101112
1/0 2/19 4/9 5/29 7/18 9/6 10/26 12/15
Date
mm
/day
Eto
Et1
Et2
Pecan Water Use/ Sammis et al.
Irrigation
Budbreak
A B C
.25
.50
.75
in/d
Water & Transpiration Irrigation & Water Management
• Evapotranspiration: water loss through evaporation and transpiration– Yearly ET: ~ 200 cm– Yearly Ppt: ~ 20 cm– Deficit: ~ 180 cm
• Daily ET (cm/d) Mar Apr May Jun Jul Aug Sep Oct
0.13 0.25 0.41 0.61 0.71 0.61 0.41 0.20
Water & Transpiration Irrigation & Water Management
• Goals of Irrigation:– Meet the needs of the plant– Minimize runoff
• erosion
• chemicals
– Minimize evaporation– Manage leaching
• salts
• NO3
Water & Transpiration Irrigation & Water Management
• When to Irrigate?– Observe plants--too late!– Observe soil--’touchy-feeley’– Measure soil or plant water stress
• tensiometer * neutron probe
• pressure bomb * electrical resistance
• leaf temperature
– Estimate water use• evapotranspiration
Water & Transpiration Irrigation & Water Management
• Reducing Water Use in the Landscape– Goal: Reduce evaporation
• water at night or early morning
• water deep to develop deep rooted plants
• apply 5 cm organic mulch to cool soil
– Goal: Put the water where you want it• directional sprinklers
• berms or swales
Water & Transpiration Irrigation & Water Management
• Reducing Water Use in the Landscape– Goal: Use low water plants
• xeriscaping
• plant breeding
• not ‘zeroscaping’
– Goal: Improve irrigation efficiency• drip irrigation
• sub-irrigation
Things to Know
• Colligative properties• Hydrologic cycle• Irrigation• Solvent• Solute• Field Capacity• Permanent Wilting Point• Water Use Efficiency• Potential Evapotranspiration
• Transpiration• Turgor• Wilting• MAD• RH• AWC• Water Potential• Xeriscaping
Water & TranspirationFactors Influencing Transpiration/ Musk mallow leaves
Base of Plant Top of Plant
Water & Transpiration
Heat of Fusion/Frost protection in vineyard
495 L/min/ha
103 L/min/ha
Water & Transpiration
Heat of Vaporization/ Peach bud bloom delay
Water & TranspirationFactors Influencing Transpiration/ Light, T, H2O
Intact leaf
Air T
Excised leaf
Citrullus colocynthis