Park et al. (2026) Irrigation Control System Based on Hanging-Gutter-Scale Evapotranspiration Measurement for Tomato (Solanum lycopersicum L.) Cultivation in Greenhouse Hydroponics

Identification

• Journal: Journal of Biosystems Engineering
• Year: 2026
• Date: 2026-01-12
• Authors: Sung Kwon Park, Min-Seok Gang, Woo-Jae Cho, H. Kim
• DOI: 10.1007/s42853-025-00285-w

Research Groups

• Department of Biosystems Engineering, Seoul National University, Seoul, Korea
• Integrated Major in Global Smart Farm, Seoul National University, Seoul, Korea
• Convergence Research Center for Smart Farm Solution, Korea Institute of Science and Technology, Seoul, Korea
• Department of Bio-Industrial Machinery Engineering, Gyeongsang National University, Jinju, Korea

Short Summary

This study developed and evaluated an hourly gutter-scale evapotranspiration (ET)–based irrigation system for greenhouse tomatoes, demonstrating its ability to reduce nutrient solution use by 23.9% compared to conventional methods while maintaining comparable crop growth and yield.

Objective

• To develop an hourly gutter-scale evapotranspiration–based irrigation system for greenhouse tomatoes cultivated in South Korea.
• To evaluate the feasibility and resource-saving effect of the developed system compared with cumulative solar radiation–based irrigation.

Study Configuration

• Spatial Scale: A single-span plastic-type greenhouse (5 m wide, 14 m long, 4 m high) in Suwon, South Korea. Two 1-meter-long hanging gutters were used, each cultivating 10 Dotaerang Dia tomato plants in four cocopeat substrate slabs.
• Temporal Scale: Two cropping cycles were conducted: the first from April 4 to May 20, 2025, for system validation, and the second from May 21 to July 1, 2025, for comparative evaluation. Evapotranspiration was measured hourly, and crop growth parameters were collected at 7-day intervals.

Methodology and Data

• Models used:
  • Water balance method for evapotranspiration (ETt = IRRt - ∆BDWt - DRAt).
  • Irrigation volume calculation: IRRt = ETt-1 × 1.2 (120% of previous hour's ET).
  • Leaf Area Index (LAI) estimation: LA = 0.347 × (leaf length × leaf width) - 10.7; LAI = ΣLAi / A.
  • Statistical analysis: T-tests (p > 0.05 for no significant difference).
• Data sources:
  • Evapotranspiration Measurement System: Three tension-type load cells (SB-75L) for gutter weight, an ultrasonic level sensor (DL-10) for drainage volume, and pre-measured dripper discharge rates (1.8 L/h). Data collected and processed by an embedded board (Raspberry Pi 4 Model B).
  • Environmental Data: Internal weather station (SH-VT260) and external weather station (Vantage Pro2) for greenhouse climate data (air temperature, relative humidity). Two pyranometers (SP-214 SS) for solar radiation.
  • Crop Growth Data: Manual measurements of plant height, stem diameter, leaf length, leaf width, and fruit yield (number and mass).

Main Results

• The developed system accurately measured hourly gutter-scale evapotranspiration, with load cells detecting simulated weight reductions of 36 ± 4 g/h.
• During the first cultivation cycle, daily evapotranspiration varied significantly (13.13 kg/day to 26.27 kg/day) based on environmental conditions and increased with crop growth, confirming the system's responsiveness to microclimate and plant development.
• In the second cycle, the evapotranspiration rate–based irrigation method reduced total nutrient solution use by 23.9% compared to the cumulative solar radiation–based method, with higher reductions (up to 33.22%) observed during early growth stages.
• The actual drainage volume was consistently maintained within the recommended range of 20–50% of irrigation volume, improving nutrient uptake and salinity control.
• No statistically significant differences (p > 0.05) were found in key crop growth parameters (leaf area index, plant height, stem diameter) or fruit yield between the two irrigation methods, indicating that resource savings did not compromise crop development.

Contributions

• Development of a novel, real-time, hourly gutter-scale evapotranspiration measurement system that addresses spatial variability in hanging-gutter hydroponic systems.
• Implementation and validation of an evapotranspiration rate–based irrigation control system for greenhouse tomatoes.
• Quantification of significant resource savings (23.9% reduction in nutrient solution) without negatively impacting crop growth or yield.
• Enhancement of water and nutrient use efficiency, contributing to environmental protection by minimizing drainage in hydroponic systems.
• Provides a foundation for integrating precise, demand-driven irrigation strategies into smart-farming platforms.

Funding

• "New Agriculture Climate Change Adaptation System Project" (RS-2023-00219322), Rural Development Administration (RDA).
• Brain Korea 21 Fostering Outstanding Universities for Research, funded by the Ministry of Education of Korea and the National Research Foundation of Korea.

Citation

@article{Park2026Irrigation,
  author = {Park, Sung Kwon and Gang, Min-Seok and Cho, Woo-Jae and Kim, H.},
  title = {Irrigation Control System Based on Hanging-Gutter-Scale Evapotranspiration Measurement for Tomato (Solanum lycopersicum L.) Cultivation in Greenhouse Hydroponics},
  journal = {Journal of Biosystems Engineering},
  year = {2026},
  doi = {10.1007/s42853-025-00285-w},
  url = {https://doi.org/10.1007/s42853-025-00285-w}
}