Journal of Bio-Environment Control (생물환경조절학회지)

The Korean Society for Bio-Environment Control (한국생물환경조절학회)
권호 표지
DOI QR코드

DOI QR Code

Quantification of Rockwool Substrate Water Content using a Capacitive Water Sensor

정전용량 수분센서의 배지 함수량 정량화

  • Baek, Jeong-Hyeon (Department of Agriculture and Life Science, Graduate School, Korea National Open University) ;
  • Park, Ju-Sung (Department of Electronics Engineering, Pusan National University) ;
  • Lee, Ho-Jin (Department of Environmental Horticulture, Graduate School, The University of Seoul) ;
  • An, Jin-Hee (Department of Agriculture and Industries, Kangwon National University Graduate School) ;
  • Choi, Eun-Young (Department of Agricultural Science, Korea National Open University)
  • 백정현 (한국방송통신대학교 대학원 농업생명과학대학) ;
  • 박주성 (부산대학교 전자공학과) ;
  • 이호진 (서울시립대학교 대학원 환경원예학과) ;
  • 안진희 (강원대학교 농산업학부 대학원) ;
  • 최은영 (한국방송통신대학교 농학과)
  • Received : 2020.11.19
  • Accepted : 2021.01.12
  • Published : 2021.01.31
Download PDF
⟨ Previous Next ⟩

Abstract

A capacitive water sensor was developed to measure the capacitance over a wide part of a substrate using an insulated electrode plate (30 cm × 10 cm) with copper and Teflon attached on either side of the substrate. This study aimed to convert the capacitance output obtained from the condenser-type capacitance sensor into the substrate water content. The quantification experiment was performed by measuring the changes in substrate water weight and capacitance while providing a nutrient solution and by subsequently comparing these values. The substrate water weight and capacitance were measured every 20 to 30 seconds using the sensor and load cell with a software developed specifically for this study. Using a curve-fitting program, the substrate water content was estimated from the output of the capacitance using the water weight and capacitance of the substrate as variables. When the amount of water supplied was increased, the capacitance tended to increase. Coefficient of variation (CV) in capacitance according to the water weight in substrate was greater with the 1.0 kg of water weight, compared with other weights. Thus, the fitting was performed with higher than 1.0 kg, from 1.7 to 6.0 kg of water weight. The correlation coefficient between the capacitance and water weight in substrate was 0.9696. The calibration equation estimated water content from the capacitance, and it was compared with the substrate water weight measured by the load cell.

정전용량 수분측정 센서는 수경용 배지 양쪽에 구리 및 테플론으로 절연된 전극판(30cm×10cm)을 부착하여 배지의 넓은 부분에 걸쳐 측정하도록 개발되었다. 본 연구는 콘덴서형 정전용량 센서로부터 출력되는 정전용량 값을 배지 함수량으로 변환하는 것이다. 정량화 실험은 양액을 공급하면서 배지 물무게와 정전용량 변화를 측정하고 그 값을 비교하는 방식으로 수행되었다. 배지 함수량과 정전용량은 본 연구를 위해 특별히 개발된 소프트웨어와 함께 센서와 로드셀을 사용하여 20~30초마다 측정되었다. 상용 curve-fitting 프로그램을 이용하여 배지 함수량과 정전용량을 변수로 정전용량 값으로 배지 함수량을 추정하였다. 공급하는 물의 양이 증가하면 정전용량도 증가하는 경향을 보였다. 배지 내 물무게에 따른 정전용량에 대한 변동계수(coefficient of variation, cv)는 배지 내 물무게가 1.0kg 수준에서 다른 무게에 비해 높아 함수량 보정은 물무게를 1.7~6.0kg 수준에서 수행하였다. 정전용량과 물무게 사이의 상관 계수는 0.996이었고 보정식에 의해 정전용량으로 추정된 함수량은 로드셀로 측정한 배지 함수량과 비교하였다.

Keywords

References

  1. Atkins R.T., T. Pangburn, R.E. Bates, and B.E. Brockett. 1998. Soil moisture determinations using capacitance probe methodology. US Army Corps of Engineers. 98-2. CRREL Spec Rep. 98-2:1-49.
  2. Bass R. and N.A. Straver. 2001. In situ monitoring water content and electrical conductivity in soilless media using a frequency-domain sensor. Acta Hortic. 562:295-303. https://doi.org/10.17660/actahortic.2001.562.34
  3. Brandelik A. and C. Hubner. 1996. Soil water determination; accurate, large and deep. Phys Chem Earth. 21:157-160. https://doi.org/10.1016/S0079-1946(97)85577-2
  4. Burnett S.E. and M.W. van Iersel. 2008. Morphology and irrigation efficiency of Gaura lindheimeri grown with capacitance sensor-controlled irrigation. HortSci. 43:1555-1560. https://doi.org/10.21273/hortsci.43.5.1555
  5. Chen L., L. Zhangzhong, W. Zheng, J. Yu, Z. Wang, L. Wang, C. Huang. 2019. Data-driven calibration of soil moisture sensor considering impacts of temperature: A case study on FDR sensors. Sensors 19:4381-4392. https://doi.org/10.3390/s19204381
  6. Erika K., G. Schmidt, and U. Bruckner. 1999. Scheduling strawberry irrigation based upon tensiometer measurement and a climatic water balance model. Sci Hortic. 81:409-424. https://doi.org/10.1016/S0304-4238(99)00030-8
  7. Gong Y., Q. Cao, and Z. Sun. 2003. The effects of soil bulk density, clay content, and temperature on soil water content measurement using time-domain reflectometry. Hydrol Process 17:3601-3614. https://doi.org/10.1002/hyp.1358
  8. Han D., J. Baek, J. Park, W. Shin, I. Cho, and E. Choi. 2019. Determination of proper irrigation scheduling for automated irrigation system based on substrate capacitance measurement device in tomato rockwool hydroponics. Protected Hort Plant Fac. 28:366-375. https://doi.org/10.12791/KSBEC.2019.28.4.366
  9. Hoppula K.I. and T.J. Salo. 2006. Tensiometer-based irrigation scheduling in perennial strawberry cultivation. Irrig Sci. 25:401-409. https://doi.org/10.1007/s00271-006-0055-7
  10. Hsiao T.C., E. Acevedo, E. Fereres, and D.W. Henderson. 1976. Water Stress, Growth and Osmotic Adjustment. Phil Trans R Soc Lond. B273:479-500.
  11. Kim S.K., H.J. Lee, H.S. Lee, B. Mun, and S.G. Lee. 2017. Effect of soil water content on growth, photosynthetic rate, and stomatal conductance of kimchi cabbage at the early growth stage after transplanting. Kor J Crop Sci. 26:151-157.
  12. Kwon Y.H., J.M. Lee, H.H. Han, S. Ryu, J.H. Jeong, G.R. Do, J.H. Han, H.C. Lee, and H.S. Park. 2016. Physiological responses for soil water stresses in 'Mihong' peach tree. Protected Hort Plant Fac. 25:255-261. https://doi.org/10.12791/KSBEC.2016.25.4.255
  13. Lee S.G., Y.W. Seo, J.W. Johnson, and B.H. Kang. 1997. Effects of water stress on leaf water potential, photosynthesis and root development in Tobacco plant. Kor J Crop Sci. 42:146-152.
  14. Murray J.D., J.D. Lea-Cox, and D.S. Ross. 2004. Time domain reflectometry accurately monitors and controls irrigation water applications in soilless substrates. Acta Hortic. 633:75-82. https://doi.org/10.17660/actahortic.2004.633.8
  15. Nemali K.S., F. Montesano, S.K. Dove, and M. W. van Iersel. 2007. Calibration and performance of water sensors in soilless substrates: ECH2O and Theta probes. Sci Hortic. 112:227-234. https://doi.org/10.1016/j.scienta.2006.12.013
  16. Park J.S., N.H. Tai, T.I. An, and J.E. Son. 2009. Analysis of moisture characteristics in rockwool slabs using time domain reflectometry (TDR) sensors and their applications to paprika cultivation. J Bio-Env Con. 18:238-243.
  17. Park S.T., K.Y. Choi, and Y.B. Lee. 2010. Water content characteristics of coconut coir substrates on different mixture ratios and irrigation rates and times. Kor J Hortic Sci Tech. 28:227-233
  18. Rhie Y.H. and J. Kim. 2017. Changes in physical properties of various coir dust and perlite mixes and their capacitance sensor volumetric water content calibrations. HortSci. 52:162-166. https://doi.org/10.21273/HORTSCI11362-16
  19. Rial W.S., and Y.J. Han. 2000. Assessing soil water content using complex permittivity. ASAE. 43:1979-1985. https://doi.org/10.13031/2013.3104
  20. Sakaki T., A. Limsuwat, and T.H. Illangasekare. 2011. A simple method for calibrating dielectric soil moisture sensors: laboratory validation in sands. Vadose Zone J. 10:526-531. https://doi.org/10.2136/vzj2010.0036
  21. Shin J.H. and J.E. Son. 2015. Irrigation criteria based on estimated transpiration and seasonal light environmental condition for greenhouse cultivation of paprika. Protected Hort Plant Fac. 24:1-7. https://doi.org/10.12791/KSBEC.2015.24.1.001
  22. Sim S.Y., S.Y. Lee, S.W. Lee, M.W. Seo, J.W. Lim, S.J. Kim, and Y.S. Kim. 2006a. Characteristics of root media water in various irrigation control methods for tomato perlite bag culture. J Bio-Environ Control. 15:225-230.
  23. Sim S.Y., S.Y. Lee, S.W. Lee, M.W. Seo, J.W. Lim, S.J. Kim, and Y.S. Kim. 2006b. Appropriate set time in irrigation system by time clock in tomato perlite bag culture. J Bio-Environ Control. 15:327-334.
  24. Smajstrla A.G. and S. J. Locascio. 1996. Tensiometer-controlled, drip-irrigation scheduling of tomato. ASABE. 12:315-319.
  25. Topp G.C., J.L. Davis, and A.P. Annan. 1980. Electromagnetic determination of soil water content: measurements in coaxial transmission lines. Water Resour Res. 16:574-582. https://doi.org/10.1029/WR016i003p00574
  26. Woo Y.H., H.J. Kim, Y.I. Nam, I.H. Cho, and Y.S. Kwon. 2000. Predicting and measuring transpiration based on phytomonitoring of tomato in greenhouse. Hort Environ Biotechnol. 41:459-463.
  27. Wraith J.M. and D. Or. 1999. Temperature effects on soil bulk dielectric permittivity measured by time domain reflectometry: experimental evidence. Water Resour. Res 35:361-369. https://doi.org/10.1029/1998WR900006