AVOCADO IRRIGATION AVOCADO IRRIGATION SEMINAR Ti i S h d li Timing-Scheduling Influence of Soil and Weather Conditions Different Irrigation Strategies Tools Available Tools Available Field Experience Discussion Presented by— Presented by Andres Bascope, Agricultural Engineer & Avocado Consultant
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AVOCADO IRRIGATION AVOCADO IRRIGATION SEMINARTi i S h d liTiming-Scheduling
Influence of Soil and Weather ConditionsDifferent Irrigation Strategies
IRRIGATION SCHEDULINGSTEP 1: Determine Soil Properties: textural classification and Water Holding Capacity
Soil Water Holding CapacitySoil Textures inches/inchCorse Sand and Gravel 0.02 0.06Sands 0.04 0.09Loamy Sands 0.06 0.12Sandy-Loam 0.11 0.15Loam and Silt Loams 0.17 0.23Clay-Loam 0.14 0.21Clay Loams and Silty-Clay-Loam 0.14 0.21Silty Caly and Clays 0.13 0.18
Web search: Soil Water Holding Capacityhtt // d d / b / /i i t / b66 ht # ilhttp://www.ag.ndsu.edu/pubs/ageng/irrigate/eb66w.htm#soilhttp://www.noble.org/ag/Soils/SoilWaterRelationships/Index.htm
at the forefront of irrigation management technology.
Washington, Idaho Nebraska and Texas
AlmondsMajor Crop Types
OrangesAlfalfaApples
Avocado
gPeaches
PistachiosPomegranatesAvocado
BlueberriesCanolaCarrots
PomegranatesPotatoes
RaspberriesR di hiCarrots
CherriesCorn
RadicchioStrawberries
TomatoesLemonsMelons
Nursery Crops
WalnutsWine Grapes
Wheat SoybeansNursery CropsOnions
WheatSoybeans
Soil Moisture – What Is It?Soil Moisture is the water in the pore spaces p p
of a soil PLUS the water held by soil itself.Soil Moisture h i iSaturation – All of the pores are filled with water.
Characteristics
Field Capacity – Some water is in the pores, but it no longer drains freelyWilt Point – Only water held Wilt Point Only water held tightly by the soil is present
Water Holding Capacity (WHC) is the total amount of plant-available water when the soilamount of plant-available water when the soil is at field capacity
Measuring Soil Moisture
Capacitance Probes Use Volumetric Soil Moisture
% Water = VSM1 cu ft Soil
Taken Water
Compress the Soils to
Separate the Soil Air and % Soils
% Air
from the Field
Soil, Air, and Water
Components
Each Element Occupies a
% Soils
Occupies a Percent of the 1
cu ft Volume
Volumetric Soil Moisture (VSM) is the total water ( )content of soil by volume measured in percent.
B th WHC d VSM Both WHC and VSM Vary Widely with Soil Typey y yp
S t ti
WHC% = 4%
S t ti
WHC% = 14%
Saturation
WHC% = 12%
l Moisture, %
Saturation46%
l Moisture, %
Saturation
Field Capacity27%
46%
l Moisture, %
Saturation
Field Capacity
Wilt30%
42%
48%
Volumetric So
il
Field Capacity
Wilt5%
9%
Volumetric So
il p y
Wilt13%
27%
Volumetric So
il
Oven Dried0%SAND
Oven Dried0%LOAM
Oven Dried0%CLAY
T t M i t ZTarget Moisture ZoneMaking More Accurate Irrigation Decisions
isture
ric Soil Moi
% Volum
etr
Lower Safety FactorLower Safety Factor
%
Time
Moisture Trend Line
Soil Moisture Response Trends: Root Activity
SUM
1 ft
Stair-Step Response Shows Roots Taking Up
Water During the Day
Stair-Step Response Shows Roots Taking Up
Water During the Day
2 ft
3 ft
and Resting at Nightand Resting at Night
3 ft
4 ft
5 ftPressure
Switch
Irrigation Events
H d it ll k?H d it ll k?How does it all work?How does it all work?
HardwareHardwareHardwareHardwareWeather station
Solar‐powered on‐board field computer
Soil probes installed down to 5 ft.
Pressure switch or rain bucket to capture irrigation event
How It WorksHow It Works…
ComputerComputer
Soil moisture data automatically collected
Soil moisture data automatically collected
Weather, soil and Weather, soil and
iPhone & Droid
iPhone & Droid
IrrigateIrrigate
every 15 minutes.every 15 minutes.
pressure switch data sent to a secure server via
pressure switch data sent to a secure server via
Irrigate with
Confidence.
Irrigate with
Confidence.P it hP it h server via
cell signal.server via cell signal.
iPadiPad
Pressure switch communicates when water is on/off.
Pressure switch communicates when water is on/off.
Limited water led to the growerLimited water led to the grower adding gypsum in May and June resulting in improved penetration.resulting in improved penetration.