Introduction: Irrigation Challenges in the Heatwave of the Summer Months
The summer months are critical period for Greek farmers, as high temperatures and intense solar radiation dramatically increase the water needs of crops. However, many producers tend to over-irrigate “just to be safe”, which results in significant water loss through runoff or evaporation. Conversely, untimely or insufficient irrigation-based on visual estimates-can leave crops under stress, reducing yields.
The Mediterranean climate, with its characteristic dry summers, and increasingly frequent heatwaves and prolonged droughts due to climate change, creates high evapotranspiration conditions that demand strategic management of every drop of irrigation water. In these demanding conditions, precision irrigation systems and smart technologies are the solution for efficient use of water resources and maintaining productivity. And evapotranspiration is the main factor in determining a crop’s water needs.
What is Evapotranspiration and Why It is Critical
Evapotranspiration (ET) is the combination of water evaporation from the soil and plant surfaces and water transpiration through plant tissues. In simple terms, ET expresses how much water is “lost” from a field to the atmosphere every day, both from the soil and from plants. This indicator is critical for irrigation because it corresponds to the amount of water that needs to be replenished by irrigation to keep the crop healthy.
The factors that affect evapotranspiration are mainly the weather conditions – temperature, solar radiation, air humidity and wind speed – as well as soil moisture (soil texture and composition affect water retention and evaporation) and the type/stage of the crop. On hot summer days, ET spikes: in a Greek orchard in July, daily evapotranspiration can exceed 5-6 mm, i.e. over 50 cubic metres of water per hectare ‘evaporates’ every day. If this water is not replenished, plants will start to suffer water stress.
ET is usually measured in millimetres of water per day and can be estimated in several ways. In modern agriculture, agro-meteorological stations installed in the field record local meteorological conditions (temperature, humidity, solar radiation, wind, rainfall, etc.). Based on this data, specialised software applies scientific formulas to accurately calculate the daily reference evapotranspiration (ETo), i.e. how much water a typical plant cover (usually grass) would need under the given conditions. Then, by applying a crop coefficient (Kc) to adjust for the specific crop type and its stage and co-assessing non-ideal factors, the actual crop evapotranspiration can be estimated.
In practical terms, knowing ET accurately answers the question: “How much water does my field need today?” For instance, if a vineyard has an ET of 5 mm on a hot day, it means each square meter has lost 5 liters of water. Smart irrigation scheduling would replace exactly those 5 liters per m² (minus any effective rainfall), ensuring that plants are neither thirsty nor waterlogged.
Smart Irrigation: Sensors, Data, and Automated Control
Smart irrigation utilizes evapotranspiration information combined with modern sensor and automation technologies, transforming the traditional irrigation system into a smart water management system. Such a system usually includes three key components:
- Field Sensors: Wireless soil sensors measure soil moisture in the root zone, while weather sensors capture meteorological conditions (temperature, air humidity, solar radiation, wind, rain). Advanced setups may also include plant sensors (e.g., stem or leaf thickness sensors) that directly detect plant water stress. All this data is collected from the field in real time.
- Software & Data Analysis: Sensor data is transmitted via internet (e.g., cellular or LoRa) to a cloud platform, where algorithms process the readings. Daily ET is calculated based on local weather data and, at the same time, soil moisture trends are monitored. The cloud platform acts as the system’s “brain”: it decides when and how much to irrigate based on crop water consumption. The farmer through the cloud platform, via computer or mobile app, sees and assesses crop conditions (e.g., soil moisture, ET, weather forecast), and receives alerts. In addition, the farmer can set rules (e.g., moisture thresholds) which can trigger automatic irrigation or alerts.
- Automatic Control Systems: Software commands are executed in the field via solenoid valves, pumps, and automation. When irrigation is needed in a specific zone, the system opens the relevant valve and irrigates only that zone and for just as long as necessary. Once the water requirement (e.g., 5 mm lost to ET) is met, the valve closes automatically. Advanced platforms also factor in weather forecasts — postponing or canceling irrigation when rain is expected, thus preventing water waste and over-saturation.
Benefits of Smart Water Management for Crops
Transitioning from conventional to smart, customized irrigation offers multiple benefits for farmers, crops, and the environment:
- Significant water savings: By adjusting the irrigation dose exactly to the ET and real-time needs, water wastage is drastically reduced. Field applications have shown 20–40% reductions in water consumption compared to conventional programs. Modern smart irrigation solutions, such as SynField, can optimize irrigation by reducing water requirements by up to 55%. This means immediate cost savings for the farmer (lower water or pumping electricity bills) and more water available in reservoirs for other uses or emergency irrigation.
- Improved crop health and yields: Irrigating at the right time and amount fosters robust plant growth and avoids drought or overwatering stress. Issues like leaf wilting, flower drop, or poor fruit set are minimized. Smart irrigation has been observed to boost yields by 20–40%, while also improving product quality (e.g., size, sugars, bioactive compounds).
- Damage prevention: In sensitive crops, timely irrigation can prevent serious losses. For instance, in citrus, water stress during heatwaves worsens fruit drop and splitting. A smart system keeping soil moist during critical periods reduces such risks. Similarly, in vineyards, smart irrigation avoids drought shock that can delay ripening or lower wine quality. Even in resilient crops like olives, targeted watering during fruiting improves significantly both quantity and quality of olive fruits and olive oil.
- Higher Water Use Efficiency: Water Use Efficiency (WUE) measures yield per unit of water consumed. With smart irrigation techniques, this efficiency is maximised. Studies have shown that practices such as drip irrigation combined with regulated deficit irrigation can lead to water savings and increased water efficiency without compromising production quality. In other words, every litre of water applied to the crop yields more fruit.
- Lower environmental impact: Avoiding over-irrigation reduces nutrient leaching from the soil. Excess water draining beyond the root zone can carry fertilizers (nitrates, phosphates) into groundwater, polluting it. Smart irrigation minimizes this, protects soil and water quality, and reduces energy consumption (fewer pump hours), lowering the carbon footprint of the farm.
- Less effort, better oversight: Automation and remote monitoring reduce labor needs. Farmers can manage irrigation from their phone, get real-time alerts, and maintain a precise log of actions—knowing when and how much they irrigated, the soil moisture, and ET. This supports data-driven management and better long-term planning.
SynField: A Greek Smart Irrigation Solution
A practical implementation of the above principles is SynField – a Greek smart farming and irrigation system developed by Synelixis. It’s a flexible and cost-effective precision agriculture solution for both small and large farms, making it ideal for the average size producer.
Conclusions: Every Drop Counts
Extreme summer temperatures and water scarcity leave no room for outdated practices. Smart water management based on evapotranspiration offers a practical, viable solution for Greek agriculture, empowering farmers with tools to meet today’s challenges. Using sensors, stations, and advanced systems, farmers become data managers-making informed decisions and automating critical processes.
The benefits from water and cost savings to higher yields and environmental protection are proven and undeniable. As climate change intensifies and competition for water resources increases, smart irrigation becomes not just a technological trend but a necessity for the sustainability of our agriculture. By investing in such solutions, farmers protect their crops from drought and heat, ensure their production in hard times, and contribute to a more efficient and sustainable agricultural future.
Let’s remember: Water is no longer just a resource-it’s a driving force of competitiveness and resilience.
Gina Athanasiou, MSc, MMus, MSc – Agronomist, Synelixis
