WayBeyond’s Optimized series is designed to turn insights into impact—one growing decision at a time.
In this edition, we focus on irrigation: how growers are using Reference Evapotranspiration (ETo) forecasting to shift from routine watering to precision scheduling.

Last month, we shared how a tomato grower reduced water use by 16% using ETo—without compromising yield or fruit quality.

Now, we’ll show you how ETo forecasting works and why it’s a simple but powerful tool for optimizing irrigation every day, in every season.

What Is ETo Forecasting?

Reference Evapotranspiration (ETo) is a climate-based estimate of how much water a reference crop (like grass) would lose through evaporation and transpiration. It uses real-time weather data to calculate this value, including:

• Temperature
• Humidity
• Wind speed
• Solar radiation

This tells you how much water your crops are likely to need—not based on guesswork or habit, but on measurable climate demand.

ETo forecasting goes a step further. Using localized weather data, it predicts this water need 24 to 48 hours in advance, allowing growers to make informed irrigation decisions ahead of time.

What ETo Forecasting Changes in Daily Irrigation

Integrating ETo forecasting into your daily planning can improve both water use and plant health. Here’s how:

1. Plan Ahead, Not After the Fact

Instead of waiting for signs of crop stress, ETo forecasts let you schedule irrigation proactively—often during early morning hours—reducing water loss and stress on the plant.

2. Adjust to Weather Changes Automatically

Weather can vary widely from day to day. ETo forecasting factors in temperature swings, humidity levels, and solar exposure, helping you avoid overwatering on cloudy days or underwatering on hot, windy ones.

3. Match Irrigation to Growth Stage

A tomato plant in flower doesn’t need the same amount of water as one in full fruit set. ETo values can be adjusted using crop coefficients (Kc) to account for each growth stage—ensuring plants get what they need, when they need it.

4. Protect the Root Zone

With more precise watering, you can avoid oversaturating substrates and keep root zone moisture within optimal levels—supporting nutrient uptake and root health.

5. Maximize Every Input

Watering based on ETo helps minimize nutrient leaching, reduce disease risk, and maintain consistent crop quality. That means healthier plants and a more efficient use of both water and fertilizer.

Why It Matters

Growers are under pressure to do more with less: fewer resources, more variability, higher quality standards.

ETo forecasting offers a practical way to move from static irrigation schedules to plant-responsive watering—based on data, not habit.

It’s not just about saving water. It’s about optimizing every input to protect yield, improve quality and increase ROI.

How to Access ETo Forecasts in FarmRoad

With FarmRoad’s Irrigation Forecast dashboard, growers get 

• Hourly ETo forecasts
• Location-specific climate data
• A clear view of predicted crop water demand

This means you can plan irrigation confidently—day by day, hour by hour—based on your environment and your crop.

Smarter irrigation starts with one shift:
Using what you already know—climate data—to do more with every drop.

Want to see how ETo forecasting fits into your system?
Let’s talk.