By Andi Anderson
Irrigation plays a key role in helping crops grow well, especially as weather becomes more uncertain. Using water at the right time and in the right amount, known as irrigation scheduling, improves yields and conserves water.
The goal of irrigation scheduling is to meet a crop's water needs, also called evapotranspiration (ET), while keeping enough moisture in the soil's root zone. Different soil types hold water differently. Sandy soils drain fast and hold less water, while clay soils hold more.
Soil water levels change after rain or irrigation. Field capacity is the maximum amount of water soil can hold for plants. When soil dries too much, it reaches the permanent wilting point. The water between these two points is available water. Farmers are advised to irrigate before 40–50% of this water is used up to avoid plant stress and yield loss.
A practical method to track water use is the checkbook method. Like balancing a bank account, farmers track rainfall and irrigation as deposits and plant water use as withdrawals. When the water balance drops near the stress point, it's time to irrigate.
Michigan State University Extension offers tools like an irrigation scheduler app and soil water balance sheets. These tools use weather data from local Enviroweather stations to help guide water use. Farmers can also estimate crop water use by multiplying the evapotranspiration rate with a crop coefficient (Kc) based on crop type and growth stage.
For real-time field data, farmers can use soil moisture sensors. These provide direct measurements and are explained in MSU Extension’s factsheet on efficient irrigation management.
By using these methods, farmers can ensure their crops get water when needed, improving both yields and water use efficiency.
Photo Credit: michigan-state-university-msu
Categories: Michigan, Crops, Corn, Soybeans