Environmentally sustainable production of tomato in a coir substrate hydroponic system using a frequency domain reflectometry sensor

Abstract

Open hydroponic systems are the most widely used hydroponic systems in Korea. However, water drainage from the open hydroponics often causes significant environmental pollution due to agrochemicals and loss of water and nutrients. The objectives of this study were to show the potential application of an irrigation schedule based on threshold values of volumetric substrate water content tomato (Solanum lycopersicum L. 'Betatini') cultivation in a commercial hydroponic farm. This study was performed for minimizing effluent from coir substrate hydroponics using a frequency domain reflectometry (FDR) sensor-automated irrigation (FAI), as compared with conventional timer-irrigation (TIMER) from the farmer's experience. The irrigation volume and retained water volume in the substrate of the TIMER during autumn to winter cultivation were 6.1-fold and 2-fold higher, respectively, than those of the FAI with slightly higher fruit weight and no difference in plant growth in the TIMER. This resulted in 1.9-fold higher water use efficiency (WUE) in the FAI. The irrigation volume and retained water volume in the substrate of TIMER during spring to summer were 3.2-fold and 1.8-fold higher, respectively, than those of the FAI with no difference in fruit weight or plant growth between the two treatments, which led to a 1.9-fold higher WUE in FAI. Approximately 61% fertilizer cost savings and a substantial decrease in drained solution volume were observed for FAI compared to those with TIMER. The use of the FAI technique for a least-drainage hydroponic system can be achieved in a large-scale hydroponic farm, resulting in efficient and environmentally sustainable use of water and fertilizer.Additional key words: leachate, retained water volume, volumetric water content, water use efficiency Hort.

Evaluation of installation procedures of volumetric water content and matric potential probes: fundamentals for obtaining field and laboratory accordance

“…About the probe's range, the Decagon's operator manual emphasizes that higher measurement frequency allows the EC-5 to measure VWC from 0 to 100% (VWC of saturated soils is generally 35 to 60% depending on the soil), and the accuracy might reach 1% for calibrated soils. However, authors like Veldkamp & O'Brien (2000) [21], Choi et al, (2015) [22], and Bore et al, (2015) [23] highlight to increase data accuracy, the equipment must be calibrated.…”

Field Measurements and Numerical Simulations of Temperature and Moisture in Highway Engineering Using a Frequency Domain Reflectometry Sensor

“…Soil moisture sensors based on FDR technology are advantageous for their features such as cheapness, speed, easy handling and less soil disturbance, and are one of the common instruments for measuring in situ soil volumetric moisture content [ 19 ]. Ye et al [ 20 ] and Choi et al [ 21 ] studied the application of FDR sensors in environmental testing and evaluation, reaching the conclusion that they were effective in the field of environmental engineering. Skierucha et al [ 22 ] studied the use of FDR for measuring the water content in different frequency ranges.…”

Influence of Volumetric Water Content in a Peat-Perlite Medium on Mother Plant Growth and Daughter Plant Occurrence during ‘Seolhyang’ Strawberry Propagatio

“…FDR 방식은 고주파를 토양에 송출 및 수신하여 수분함량별 유전율(dielectric constant)에 따라 정전용량(electric capacity)을 평가함으로써 토양수분함량을 측정하는 것이다 (Choi et al, 2016a). 그러나 아직 많은 채소작 물에 적용되지 않고 있으며, Choi et al(2014Choi et al( , 2015Choi et al( , 2016a 하수로 관수하여 식물체의 무기원소 함량을 최저수준으로 조절하고 본엽 3매를 남긴 채 적엽하였으며 GS3 센서를 설치하였 다(Fig. 1A).…”