Definition: Irrigation system water demand is the amount of water required to meet the evapotranspiration (ET) needs of the crop, considering the irrigation efficiency. In other words, it's the volume of water that needs to be applied to the crop zone after accounting for losses due to evaporation, deep drainage, and other factors.
The three factors crop coefficient (Kc), irrigation efficiency (Ei), and irrigation time period, all play a crucial role in determining irrigation water demand
Irrigation Calculator
Understanding Irrigation Management: Crop Coefficient, Irrigation Efficiency, and Irrigation Time Period
Crop Coefficient (Kc):
The crop coefficient (Kc) is a factor that accounts for the difference in water use between a specific crop and the reference crop (usually well-watered grass). It essentially tells you how much a particular crop transpires compared to the reference crop under the same conditions. Kc values vary depending on the crop type, growth stage, and climatic conditions. For example, corn will have a different Kc than tomatoes, and both will have varying Kc values throughout their growing seasons.
Example of various Crop Coefficient:
Here's a table listing crop coefficients (Kc) for various irrigation plants in general use. These are averages and can vary depending on the specific growth stage and climatic conditions. It's always recommended to consult local resources or agricultural extension services for the most accurate Kc values for your specific situation.
Crop Type Kc Range
Alfalfa1.10 - 1.25
Barley0.80 - 1.10
Corn0.80 - 1.10
Cotton0.80 - 1.20
Fruits (orchards)0.70 - 1.00
Grass (lawns)0.70 - 0.85
Peanuts0.80 - 1.10
Potatoes0.70 - 1.00
Rice1.00 - 1.20
Soybeans0.80 - 1.10
Sugarcane1.20 - 1.40
Tomatoes0.70 - 1.10
Vegetables (general)0.70 - 1.00
Wheat0.80 - 1.10