By Angie Gradiz Menjivar
Timing and application rate are critical when it comes to irrigation. Applying water too early, too late, too little or in excess can lead to wasted water, reduced crop performance, and increased plant stress. As weather patterns become more unpredictable and water becomes an increasingly valuable resource, adopting strategies to apply water at the right time and in the right amount, known as irrigation scheduling, is essential for crop and water productivity.
There are several tools available to help with irrigation scheduling, but first it’s important to understand the basics. The primary role of irrigation scheduling is to apply water in a way that meets the crop’s water demand, also known as evapotranspiration (ET). The goal is to maintain adequate soil moisture within the root zone, ensuring water is readily available to the plants when they need it most.
Soil serves as a reservoir for water, and its capacity to store water varies depending on soil texture. Sandy soils drain faster and hold less water while clay soils retain more. After rainfall or irrigation, water drains through the soil, and what remains is called field capacity, the maximum water available to plants. If the soil dries out too much, it reaches the permanent wilting point, when plants can no longer access water and may begin to die. When soil pores are completely filled with water, saturation occurs, often resulting in runoff or deep percolation; water draining below the root zone and becoming unavailable to plants.