Transcript Soil and Water

Soil and Water
SOILS
Texture: % of sand, silt, and clay
 Amount of water stored in soil
Texture
SOILS
Structure: arrangement of particles
 Amount of pore space
SOIL MOISTURE
 Gravitational water: drains through soil
by gravity
SOIL MOISTURE
 Field capacity: soil moisture after
gravitational water has been allowed to
drain (24 hours)
SOIL MOISTURE
 Permanent wilting point: plants can no
longer extract moisture
INTAKE RATE
 How quickly water enters the soil
 Slows down as soil becomes wet
 Cycle and Soak programs
AVAILABLE WATER
HOLDING CAPACITY (AW)
 Amount of soil moisture between field
capacity and permanent wilting point
EVAPOTRANSPIRATION (ET)
 Total water loss from evaporation and
transpiration
 Evaporation: loss of water from soil
surface
 Transpiration: loss of water through
plant for cooling
EVAPOTRANSPIRATION (ET)
 ET0 is a reference ET, locally or
regionally
 http://www.clemson.edu/public/rec/edisto/
facilities/
 http://fawn.ifas.ufl.edu/
 http://edis.ifas.ufl.edu/ae455
PLANT REQUIREMENTS
 Plant water needs vary
 Root depth and physiology
 Hydrozones: separating irrigation zones
by plants
 Turf, flowers, tree and shrub beds
IRRIGATION SCHEDULING
1. HOW MUCH WATER IS LOST PER
DAY?
 Loss of water through ET (inches per
day)
WATER LOSS = ET
IRRIGATION SCHEDULING
2. HOW MUCH WATER CAN BE LOST
BEFORE REPLACING IT WITH
IRRIGATION?
 The READILY AVAILABLE WATER!
IRRIGATION SCHEDULING
READILY AVAILABLE WATER
 Don’t wait until all the water is gone from
the soil!
Readily Available Water =
Root Water x Management Allowed Depletion
IRRIGATION SCHEDULING
Root Water
= Root Depth x Available Water Holding Capacity
 Root depth of plants to be irrigated
 Available water holding capacity of soil
 Sand
 Silt
 Clay
IRRIGATION SCHEDULING
Management Allowed Depletion
 The amount of water allowed to deplete
from soil before it’s replaced
 Use table
IRRIGATION SCHEDULING
3. HOW OFTEN SHOULD YOU
IRRIGATE? (Days)
 Readily Available Water ÷ ET
 Round the days up or down to a whole number
IRRIGATION SCHEDULING
4. HOW MUCH SHOULD YOU
IRRIGATE?
 = Days X ET
IRRIGATION SCHEDULING
5. HOW MANY MINUTES DO YOU RUN
IRRIGATION?
 (Irrigation Amount ÷ Precipitation Rate) X 60
 Precipitation rate: how fast water is being
applied
 Inches / hour