How to Find Plant Available Water

Plants need water to survive and thrive, and the amount of water available to them can greatly affect their growth and yield. Understanding how much water is available to plants is essential for efficient irrigation and helps farmers and gardeners optimize their water use while ensuring that plants receive the necessary water to thrive.

Evapotranspiration and Soil Moisture

Two factors play a significant role in finding plant-available water: evapotranspiration and soil moisture. Evapotranspiration is the water lost from a plant's leaves and the surrounding soil due to evaporation and transpiration. Transpiration is the process by which water moves from plant roots through the plant to the leaves, where it is evaporated. Soil moisture refers to the amount of water present in the soil that plants can access.

Measuring Soil Moisture

There are several methods to measure soil moisture, including tensiometers, gypsum blocks, and capacitance sensors. Tensiometers measure the amount of suction that the soil exerts on water, while gypsum blocks detect the electrical conductivity of soil water. Capacitance sensors measure the soil's ability to hold an electric charge, which is related to soil moisture content.

Using the Feel Method

One low-tech method to estimate soil moisture is the feel method. By taking a handful of soil and squeezing it, you can estimate soil moisture content. If the soil holds its shape when squeezed but breaks apart when touched, it is likely at around 50% of its moisture-holding capacity, which is considered an ideal level for plant growth.

Estimating Water Use

Knowing how much water plants are using is also essential for efficient irrigation. Plant water use depends on several factors, including the plant's species, stage of growth, and environmental conditions such as temperature, humidity, and wind. Weather stations can help estimate plant water use by measuring temperature, humidity, and wind speed. By combining these data with plant-specific coefficients, farmers and gardeners can estimate plant water use and determine how much water is needed for irrigation.

Conclusion

By understanding evapotranspiration and soil moisture and using appropriate methods for measuring and estimating them, farmers and gardeners can optimize plant available water and ensure that plants receive the necessary water to thrive while minimizing water waste. Efficient irrigation not only helps save water but can also lower production costs and increase plant yield.