Deciding when to irrigate a crop and how much water to apply is a re-occurring decision that is made when managing irrigated crops. It is an important decision that affects crop productivity and quality, the cost of production, and profits. Sometimes water conveyance and distribution schedules or a limited supply of water and time for irrigation largely influence these decisions. However, as more groundwater is used for crop irrigation and as advances with surface water delivery systems progress producers can consider irrigating more according to crop water demand, which is dependent upon the type of crop, stage of crop development, soil types, weather conditions, and other factors.
Types of Irrigation Scheduling Tools
Irrigation scheduling tools consist of devices and techniques that may help understand crop water demand and help answer the question of when and how much irrigation water to apply. Any one or a combination of three approaches may be taken to acquire information on crop water demand. They include:
- Tracking weather conditions;
- Monitoring soil moisture ; and
- Measuring crop water stress.
Selected Research Reports and Publications
University of California Cooperative Extension Farm Advisors, Extension Specialists, and faculty have worked collaboratively to experiment with a variety of irrigation scheduling tools. Below are some related publications and research reports.Effects of Water Stress on Walnuts
Regulated Deficit Irrigation in English Walnuts
Understanding Regulated Deficit Irrigation in Walnuts
Relationships between SCP, Soil Moisture and Shoot Growth
Deficit Irrigation Management During Almond Hull Split
Almond RDI and Consumptive Water Use
Seeking Information
Weekly Soil Moisture Loss Reports based upon real-time regional weather conditions from public databases are provided on this website to help understand crop water demand.
Soil moisture monitoring tools are discussed below along with a brief example of field data and general interpretive guidelines for soil moisture tension measurements:
Soil Moisture Monitoring
Example Set of Soil Moisture Tension Data
Guidelines for Interpreting Soil Moisture Tensions
Tools for measuring crop water status, a brief example of field data, and brief interpretative guidelines for midday stem water potential measurements with a pressure chamber are provided below:
Measuring Crop Water Status in Orchard Crops
Example Set of SWP Data in Walnut
Midday Stem Water Potential Interpretative Guidelines