Transcript Document
Gregg Hartt
Citrus Agent I
Highlands County Extension
4509 George Boulevard
Sebring, Florida 33875-5837
Voice - 863-402-6540
FAX - 863-402-6544
SUN - 718-6540
Email – [email protected]
Irrigation Scheduling:
Maximizing Production
Efficiencies While Minimizing
Citrus Production Costs
Irrigation Considerations
Crop use requirements
– Seedy
– Seedless
– Rootstock
– Variety
– Crop load
Irrigation Considerations
Soil texture & profile
Rainfall frequency and quantity
Temperature, humidity, and wind
Evapotranspiration rate
Efficiency of irrigation system
Irrigation Considerations
Soil moisture depletion
Irrigation maintenance
Permitted quantities
Ag Mod in SWUCA II
Leaching
Development stage of crop
Irrigation Considerations
Varietal differences in water use requirements
Citrus needs about 47 acre inches per year to grow
a crop
During the spring flush the soil moisture should
not be allowed to fall below 2/3 available water
(AW) and this level of moisture should be
maintained until the fruit is at least 1” in diameter.
AW is the difference between field capacity &
wilting point
Irrigation Considerations
AW for sands & fine sands is averaged at
¾”
Sandy & fine sandy loams averages 1.25”
of AW
Very fine sandy loams to silt clay loams
average 1.5” AW
Silt clay to clay averages 2” AW
Peats & mucks average 2.25” AW
Irrigation Considerations
Seedy varieties need less water than
seedless varieties
Rootstock
February thru June is the critical irrigation
period for fruit set
Over irrigation in the fall can reduce fruit
solids
Tree age and size
Florida Automated Weather
Network (FAWN)
Air temperatures @ 2ft., 6ft., & 30ft.
Soil temperature @ 4”
Rainfall
Dew point @ 30 ft. (estimated value)
Relative humidity
Wind speed
Wind direction
Solar radiation
FAWN Management Tools
Irrigation scheduler
– Young trees
– Mature ridge
– Mature flatwoods
Based on an 80% efficiency of system
Wet bulb irrigation cutoff
Minimum temperature estimator calculated
at sunset
FAWN Management Tools
Archived weather data
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Reports
Latest readings
Graph data
Chart data
Chart historical data
Latest observations for each station in table
format
Mobile Irrigation Lab
Joint service provided by the Water
Management Districts and NRCS
– Evaluates the efficiency of your irrigation
Mass Flow
Considered to be the most important mode
of nutrient uptake
Relates to the movement of soil water
towards the root surface
The nutrient uptake through this mechanism
is directly related to the amount of water
used by the plants (transpiration)
Mass Flow
Responsible for supplying the root with
much of the plant needs for nitrogen,
calcium, and magnesium, but does not do so
in the case of phosphorous or potassium
Largely dependent on the moisture status of
the soil and is highly influenced by the soil
physical properties controlling the
movement of soil water
Diffusion
Ions in the soil move from a point of higher
concentration to a point of lower concentration
Enables the movement of nutrient ions without the
movement of water. An adequate supply of water
in the soil is essential for nutrient solubilization.
This mechanism is predominant in supplying most
of the phosphorous and potassium
Rootstock Drought Tolerance
Cleopatra Mandarin – intermediate to good
Swingle Citrumelo – poor to intermediate
Carrizo Citrange – good
Volkamer Lemon – good
Rough Lemon – good
Smooth Flat Seville – good
Sour Orange – intermediate
Sun Chu Sha – intermediate to good
Soil Series
Astatula
– Wholly within the ridge part of the state
– Very similar to Archbold, Candler, Orsino,
Paola, St. Lucie, and Tavares
– Moderately sloping, excessively drained,
droughty soils
– Soil reaction ranges from very strongly acid to
slightly acid
– Sand to fine sand to a depth of 80” or more
Soil Series
Immokalee
– Nearly level, poorly drained soils
– Found in broad areas of the flatwoods
– Very strongly acid
– Very similar to Basinger, Felda, Myakka, Pomello,
Satellite, and Smyrna
– Pomello and Satellite soils are better drained than
Immokalee
– Sand; single grained; loose