Introduction

Onion is one of the most sensitive crops to fluctuations in water and nutrient supply. Due to its shallow root system, concentrated in the top 30 cm of soil, the plant depends heavily on stable soil moisture and uniform nutrient distribution. In 2025, Breznik Farm in cooperation with DRT Agro implemented a project based on drip irrigation using well water and a fertigation program adapted to the field’s specific soil and climatic conditions. The goal was to achieve a healthy, uniform, and storable onion crop.

Advantages of drip irrigation for onions

Drip irrigation delivers water directly to the root zone, preventing excessive surface wetting and water stagnation, which are the main causes of root rot. This system can save up to 40% of water, reduce weed growth, and ensure uniform plant development. Thanks to stable soil moisture and the ability to apply fertilizers through irrigation, onions form firm, healthy bulbs with excellent storability.

Drip irrigation technology and importance of filtration

The system was designed according to the medium-loam soil type and the field layout. Drip tapes with 20 cm emitter spacing and a discharge rate of about 1 L/h at a pressure of 0.8–1.0 bar were used. This spacing ensures overlapping wetting zones and uniform moisture distribution within the active root zone (0–30 cm), where up to 80% of the onion roots are concentrated. Two drip lines per bed were installed, providing uniform watering across the entire width.

Water filtration plays a crucial role in maintaining system stability and uniform pressure throughout the network. Even small amounts of sand or organic debris can clog emitters over time, leading to uneven irrigation and plant stress. To prevent such issues, an A4 In Out 2×P2030 + HD-A4 filtration system was used, which includes a hydrocyclone and a dual automatic mesh filter with a self-cleaning function, mounted on a chassis with an integrated fertilizer tank for solution preparation and dosing. The system automatically flushes when the pressure differential increases, without interrupting water flow, ensuring stable pressure and even discharge across all drip lines.

Fertigation and agronomic supervision

Irrigation was performed in short, frequent cycles, maintaining soil moisture between 75–85% of field capacity. Fertigation was applied according to crop growth stages: nitrogen, phosphorus, and calcium during early growth; potassium, magnesium, and micronutrients during bulb thickening; and reduced nitrogen with increased potassium during ripening to improve dry matter content and storability. Fully water-soluble fertilizers from the Hydroponica and Novalon lines were used, along with micronutrient formulations Doctoleaf and Powerfol. Pesticides, including Binevia, were also applied through the drip irrigation system. The project was carried out under full agronomic supervision by DRT Agro.

Results of the 2025 season

By the end of the season, the farm achieved a yield of approximately 90 t/ha. Plants developed uniformly, with negligible losses. The onion bulbs were firm and consistent, with a dry matter content of 12–14%, and showed excellent storage performance without mass loss or signs of rot.

Conclusion

The results showed that the combination of drip irrigation, proper filtration and planned fertigation is key to successful onion production. DRT Agro technology made it possible to establish a stable irrigation regime and balanced plant nutrition, which was reflected in the quality and storability of the crop. If you are interested in this type of irrigation system, the turnkey project price depends on the size of the area. The cost of such a drip irrigation system typically starts from approximately EUR 2,150 per hectare.