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Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/17/2017 Publication Date: 11/1/2017 Citation: Jabro, J.D., Iversen, W.M., Stevens, W.B., Allen, B.L., Sainju, U.M. 2017. A new automated passive capillary lysimeter for logging real-time drainage water fluxes. Applied Engineering in Agriculture. 33(6):849-857. doi:10.13031/aea.12433. Interpretive Summary: Water samplers or lysimeters are devices used to capture and measure soil water from within the soil root zone in order to quantify chemical characteristics of water which has leached through the soil profile. We designed and built sixteen automated passive capillary water samplers (PCAPs) with a collection system superior in design, technology, and sophistication to other previous designs. The PCAPs were constructed of 32 cm diameter polyvinyl chloride pipe 75 cm long with a collecting surface constructed of high density polyethylene 1 cm thick and the collection surface area of 1000 cm2. Automated drainage water monitoring provides a maximally efficient and cost effective means of estimating nitrate leaching below the rootzone. These new water samplers are equipped with sensing technologies and automated data loggers. Our 4-yr results confirm that our automated PCAPs offers a reliable and convenient way to constantly monitored real-time online drainage water amounts below the rootzone of a cropping system without the necessity for costly and time-consuming methods. Technical Abstract: Effective monitoring of chemical transport through the soil profile requires accurate and appropriate instrumentation to measure drainage water fluxes below the root zone of cropping system. The objectives of this study were to methodically describe in detail the construction and installation of a new automated PCAP (passive capillary) lysimeter design, and to evaluate the performance and efficiency of this design for logging and monitoring real-time drainage water fluxes occurring below the rootzone of corn (Zea mays L.) and soybean (Glycine max L.) under an overhead sprinkler irrigation system. Sixteen automated PCAP lysimeters with outside dimensions of 32.39 cm in diameter ×74.8 cm height (1000 cm2 surface area) were designed, constructed, and placed 90 cm below the soil surface in a Lihen sandy loam. Two watermark soil moisture and temperature sensors were positioned at 30 and 76 cm depths above each PCAP to monitor soil temperature and water potential continuously. This new design incorporated wireless spread spectrum technology to enable an automated datalogger to transmit drainage water amounts simultaneously every 15 minutes to a remote host. Logged drainage amounts were compared with those manually collected using several statistical methods. The RMSE, EF, and MD were 0.0375 mm, 0.964 and 0.0335 mm, respectively, for 4-yr combined data. The mean difference (MD) between logged and collected drainage amounts was very small and not significantly different from zero for 4-yr combined results. Statistical results indicated that the new lysimeter performed exceptionally well and was capable of monitoring drainage water fluxes in the vadose zone. Real-time seamless monitoring and logging drainage water fluxes was thus possible without the need for costly time-consuming supportive procedures. |
