Irrigation Scheduling

Irrigation scheduling includes when to irrigate and how much to apply. The optimum irrigation meets the plant needs for water and avoids excess leaching to groundwater.

Overview of Methods

Methods to Determine when to Irrigate
Source: Univ of Arizona | Provides an overview of the different management techniques for irrigation scheduling, introducing both soil moisture techniques and plant indicators/ evapotranspiration.

Guidelines for computing crop water requirements
Source: FAO | An overview of the water balance method of irrigation covering concepts, equations, a list of effective root zones for common crops and how to forecast irrigation needs.

Irrigation Water Management
Source: NRCS | Brochure provides an overview of the elements of modern irrigation scheduling and reasons for more precise water application.

Effective Irrigation Practices
Source: NRCS | Guidelines for improving water management in general and for common irrigation methods.

Irrigation Management Website
Source: UCCE | A collection of presentations and publications about irrigation management by Larry Schwankl, University of California Cooperative Extension specialist.

Irrigation Management Informational website
Source: CA Ag Water Stewardship Initiative | A website with information about irrigation management and links to practical resources to help achieve more effective irrigation and efficient water use. There are also links to support organizations, irrigation technology companies and case studies.

Irrigation Management Presentations
Source: UCCE | View presentations on several irrigation topics including irrigation efficiency, irrigation uniformity, measuring water and tail water return.

Irrigation Education
Source:  Cornerstone | An interactive online source of irrigation training over a wide array of topics with technical detail:  irrigation solutions, technology, control panels, water application, sprinklers.

Irrigation Scheduling Water Balance Method
Source: UC Davis Biometeorology | The water balance approach completely described with definition, equations and plots accompanying all the major concepts.

Basic Irrigation Scheduling
Source: UC Davis Biometeorology | The Basic Irrigation Scheduling application in MS Excel plus instructions can be downloaded from this site. Available in English and Spanish.

Irrigation Scheduling: The Water Balance Approach
Source: Co State University | Description of the water balance approach to irrigation scheduling that includes equations for calculating important factors and tables by crop type for soil management depth.

Water Budget Irrigation Scheduling and Wateright
Source: CSU Fresno | A description with examples of how the different elements involved in water budget irrigation scheduling: effective root zone, management allowable depletion (MAD) and crop evapotranspiration.

Tips on Irrigating Vegetables
Source: UCCE Small Farm Program | An overview of vegetable irrigation on small farms includes information on pre-irrigation, choice of sprinkler or drip, layout and application rate how-to’s, and guidance on how long to irrigate.

Crops: Irrigation Concepts and Crop Specific Information including MAD
Source: NESPAL | An overview of the important factors involved in irrigation scheduling, including critical periods for different plants and management allowable depletion by crop type.

Method to Improve Alfalfa & Pasture Irrigation Management
Source: UCCE | Learn about irrigation strategies, considerations, and the use of soil moisture sensors for alfalfa and pasture irrigation management.

Container Nursery & Business Management Manual
Source: UC ANR | Chapter on irrigation management practices provides information on irrigation efficiency and scheduling for nurseries and includes calculation worksheets.

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All-In-One Systems

Source: UCCE | Learn about the CropManage online database-driven tool that assists growers and farm managers in determining water and nitrogen fertilizer applications on a field-by-field basis.

Irrolis Web Based Irrigation Management Software
Source: Hortau | An integrated system of field sensors, on-site weather data and software to provide irrigation scheduling.

AgRite Automated Irrigation and Fertilizer Injection Systems
Source: AgRite | AgRite provides an automated irrigation system that includes software, control panel, valves, and sensors.

Signature Irrigation & Equipment Control
Source: Signature | This system allows scheduling and remotely activating irrigation based on sensor data transmitted to a PC, tablet or phone.

Crop Production Services
Source: Crop Production Services | Capacity to integrate multiple systems for irrigation management into graphic displays for computers, tablets or cell phones including flow metering, soil moisture sensing, and evapotranspiration data.

Hortau Simplified Irrigation
Source: Hortau | An illustrated description of the Hortau irrigation monitoring system including moisture sensors, field stations, weather station and software output seen by the system user, i.e. irrigator, grower.

Tule Irrigation Systems
Source: Tule | Technology to measure actual evapotranspiration on a field is coupled with a plant response index meausuring stress, which is then used to recommend irrigation application based on grower set points for replacing ET.

Source: gThrive | Portable, multi-sensor (soil moisture, EC, temperature, more) system that enables remote monitoring from a smartphone or laptop. Integrates with leading irrigation control systems.

Rain Bird ClimateMinder
Source: Rain Bird | A system for monitoring climate and plant conditions and controlling irrigation using a wireless network.

PureSense Irrigation Scheduling, Monitoring and Control
Source: PureSense | Product line for PureSense describing their irrigation scheduling support tools & systems, including the software management system. Specific elements of the system include irrigation applied, depth of penetration, root health, climate, flow, pump control and nutrient events.

Ranch Systems Irrigation Scheduling, Monitoring and Control
Source: Ranch Systems | The RanchMaster program is an all-in-one system that tracks soil moisture, irrigation equipment control, weather and climate, tank and pond levels, and remote cameras. Their Alerting system allows users to set triggers for receiving notification when variables reach a critical point. Their system also allows for different levels of automation as well as frost response systems.

Irrometer Remote Data Options
Source: Irrometer | Videos of different systems for remotely communicating sensor data. Irrometer’s line of products allows for different levels of automation and control. They reference dealers and consultants on their website.

Wireless Irrigation Network
Source: RCD Santa Cruz County | Description of a community effort to improve irrigation efficiency through creating a cooperative cell tower system that transmits field sensor information for irrigation management.

Pajaro Valley Wireless Network Technology Loaner Program
Source: RCD Santa Cruz County | Description of the Pajaro Valley Wireless Network, associated water savings, and loaner program for Hourtau sensors.

Irrigation Scheduling Calculator for Avocados
Source: Hofshi Foundation | The “Tools” link on this page contains links to the irrigation scheduling calculator for avocados. The user enters Distribution Uniformity, Eto, Kc, Leaching Requirement and emmitter information and the calculator determines the gallons and irrigation time needed.

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Determining the Size of your Soil Reservoir

Identify Root Zone Depth

Root Zone Moisture Extraction Depths for Common Crops
Source: NRCS | Table NJ3.4 lists effective root zone extraction depth in unrestricted soils (top 50% of the root zone).

Readily Available Water in the root zone
Source: FAO | See MAD ranges in TABLE 22. Ranges of maximum effective rooting depth and soil water depletion fraction for no stress for common crops.

Effective Root Zone Depths
Source: So Jersey RCD Council | A list of common crops and effective root zones in inches.

Available Water Holding Capacity

The available water holding capacity (AWHC) is the portion of water that can be absorbed by plant roots. By definition it is the amount of water available, stored, or released between field capacity and the permanent wilting point water contents.

Web Soil Survey Instructions
Source: NRCS | Instructions for how to use the web soil survey online tool to obtain soil type and soil properties in a specified area of interest.

Web Soil Survey Link
Source: NRCS | The Available Water Holding Capacity for a specific location can be found using the NRCS Web Soil Survey by first going to the WSS link After defining an area of interest on the map click to the tabs: Soil Data Explorer and Soil Properties and Qualities. In the left hand menu, choose the Soil Physical Properties option and find Available Water Capacity. A menu will display and you should select the desired options and then choose “View Rating”. This will provide you with an AWC rating table for different soil types and slopes. You can find the rating at a specific location using the i tool in the map’s toolbar.

Field Capacity (FC) and Permanent Wilting Point (PWP)
Source: Decagon | Descriptions of field capacity and permanent wilting point along with measures of total available water holding capacity for different soil types.

Available Water Holding Capacity, Field Capacity (FC) and Permanent Wilting Point (PWP)
Source: Cornell University | Descriptions of field capacity and permantnt wilting point along with measures of these for different soil types. Also includes an explanation of how to estimate field capacity using soil moisture data.

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Determining Manageable Allowable Depletion

Rain Bird Management Allowable Depletion (MAD) for Irrigation Scheduling
Source: Rain Bird | This brochure describes how to use MAD for determining an irrigation schedule. It also describes Rain Bird technology for managing irrigation using MAD.

Soil Moisture Measurement – Determining Actual Depletion

Concepts – Soil Moisture Storage and Measurement

Irrometer Agricultural Videos
Source: Irrometer | View a variety of videos that demonstrate how to install sensors and that describe water savings & improved plant growth from irrigation scheduling technology. Some available in Spanish.

Selecting Soil Moisture Monitoring System / Service
Source: NRCS | Questions to ask when shopping for a soil moisture monitoring system or service

Practical Use of Soil Moisture Sensors for Irrigation Scheduling
Source: Troy Peters | Description of different types of sensors including their advantages and disadvantages plus available water capacity of different soil textures.

Soil Water Storage
Source: Cornell University | Description of soil water storage quantification and the factors that affect it. Includes soil moister tension curves for different soil types.

Estimating Generalized soil water characteristics from texture
Source: Saxton et al. | Soil texture influences the water holding characteristics and how difficult it is for the plant to extract water from the soil. This paper includes curves for soil moisture tension characteristics for different soil textures.

Sensors and Instruments

Measuring Water Application
Source: McCrometer | Different technologies for measuring flow so that you can track how much water is applied.

Instruments for Measuring Water Potential
Source: Decagon | Display of the water potential range measured by different sensor types.

Volumetric Water Content Concepts
Source: Argonne National Laboratory | Description and equations for computing volumetric water content.

Volumetric Water Content Sensors
Source: Decagon | Descriptions of the Decagon product line of volumetric water content sensors, installation video and how to choose a sensor.

Volumetric Water Content Sensors
Source: Campbell Scientific | Descriptions of the Vernier volumetric water content sensors.

Volumetric Water Content Sensors
Source: Vernier | Descriptions of the Campbell Scientific product line of volumetric water content sensors plus Q&A facts.

Irrometer Soil Moisture Measurement
Source: Irrometer | Description of soil moisture sensors, tensiometers, and watermark sensors.

Decagon Soil Moisture Sensors
Source: Decagon | Overview of the types of sensors provided by Decagon and their services.

Matrix Sensor to Measure Soil Matric Potential for Irrigation Management
Source: U of Nebraska | Overview of irrigation management based on soil water potential and the principles and use of Watermark sensors.

Tensiometers for Soil Moisture Measurement and Irrigation Scheduling
Source: U. of Florida | Description of how soil moisture tensiometers work, where to place them, field installation guidance, and how field data looks graphically.

Product Line of Irrometer Tensiometers
Source: Spectrum Technologies Inc. | Product Line of Irrometer Tensiometers.

Tensiometers and common design flaws
Source: Decagon | Description of basic design flaws of old school tensiometers.

Product line of tensiometers and other moisture sensors
Source: Decagon | Soil water potential with a video describing the different types of sensors, their uses and precision.

Electrical Interface for Watermark or Gypsum Block Sensors
Source: EME Systems | Description of the Watermark or gypsum block sensors and the electrical interface for routing to data logger, controller or meter.

Effectiveness of tensiometers and electrical resistance sensors varies with soil conditions
Source: UCCE | An evaluation of different types of sensors for their response to soil moisture content and appropriateness for irrigation scheduling.

Estimating Soil Moisture by Feel
Source: UCCE | How different soil types feel or look at different levels of soil moisture.

Estimating Soil Moisture by Feel and Appearance
Source: NRCS | Methods for estimating soil moisture by feel and apprearance, with links to different soil textures and photo imagery.

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Evapotranspiration Based Irrigation Management

CA ETo Data for Irrigation Scheduling & Design
Source: Cal Poly ITRC | Download data tables for crop evapo-transpiration rates by month for different zones for wet, dry and typical years.

Using Modified Atmometers for Irrigation Management
Source: Univ of Nebraska | Learn how to use an atmometer to measure evapotranspiration rates onsite and how to calculate crop water needs for irrigation scheduling.

Irrigation Management using CIMIS stations
Source: DWR | CIMIS provides daily ETo from weather stations located throughout California and information on how to convert to ETc based on crop coefficients.

Crop Water Use based on Crop Coefficients
Source: CDWR | Description of crop coefficients and how they are used in managing irrigation water application.

Avocado Irrigation Calculator Using CIMIS
Source: UCCE | Instructions for using the Avocado Irrigation Calculator.

Irrigation Scheduling Calculator for Avocados
Source: Hofshi Foundation | The “Tools” link on this page contains links to the irrigation scheduling calculator for avocados. The user enters Distribution Uniformity, ETo, Kc, Leaching Requirement and emmitter information and the calculator determines the gallons and irrigation time needed.

Salt Leaching Requirement

Drip Irrigation Salinity Management for Row Crops
Source: UCCE | Concepts and techniques for controlling salinity under drip irrigation.

Factoring in Irrigation Efficiency

Irrigation Systems and Water Application Efficiencies
Source: CSU Fresno | The importance of irrigation efficiency and distribution uniformity and how these relate to irrigation scheduling. Includes a table of different irrigation types and their attainable efficiencies.

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Toolkit at FarmsReach
Source: FarmsReach | View the tools compiled by FarmsReach related to Water and Irrigation.

Irrigation Assessment Toolkit

The development of this toolkit was funded by a grant from the Western Sustainable Agriculture Research and Education Program. Programs and projects supported by Western SARE are equally open to all people.

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