First, MSMS should derive a model which can help to transfer the resistance value into water content more accurately. Right now, the MSMS can only give the resistance of the soil and the reading is unstable. Besides, MSMS shows a better performance under high water content soil compared with TDR sensors. Thus, the accuracy between the high and low water content of MSMS could be examined in the future. This study can be extended to develop a circuit board and add remote data transfer system and thus can collect data for monitoring the underground water level.
Second, the sensor of detecting the ammonia (Figure 14) will be developed to help to monitoring the soil ammonia concentration. Since ammonia can only be detected in a wet condition, hydrogel will be covered a three-electrode sensor and a layer of ionophore mixed with PVC. Eventually the in-situ ammonia sensor along with MSMS sensors will give the ammonia data to help to calibrate, constrain, and validate the nitrogen cycling in hydrology model.
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Figure and Table List
Figure 1. Installation of the sensor kits with multiple pieces of MSMS sensors (a) and multiple pieces of commercial sensors individually (b) along soil depth in the field tests.
Figure 2 The side-side comparison of the resistance readings of MSMS at the shallow depth (7 cm below the ground) and the commercial sensors over time and the linear regression. (a: the variation of MSMS data and commercial sensor data throughout the test period, b: the correlation of MSMS data with commercial sensor data in the first 26 days, c: the correlation of MSMS data with commercial sensor data throughout the test period.)
Figure 3. The contact of MSMS sensor and soil during soil sink along soil depth (a) and the contact of commercial sensor and soil during soil settlement (b).
Figure 4 The side-side comparison of the resistance readings of MSMS at the middle depth (40 cm below the ground) and the commercial sensors over time and the linear regression. (a: the variation of MSMS data and commercial sensor data throughout the test period, b: the correlation of MSMS data with commercial sensor data in the first 27 days, c: the correlation of MSMS data with commercial sensor data throughout the test period.).
Figure 5 The side-side comparison of the resistance readings of MSMS at the deep depth (75 cm below the ground) and the commercial sensors over time (a: the variation of MSMS data and commercial sensor data throughout the test period, b: the correlation of MSMS data with
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commercial sensor data in the first 27 days, c: the correlation of MSMS data with commercial sensor data throughout the test period.)
Figure 6. The side-side comparison of the capacitance readings of MSMS at the shallow depth (7 cm below ground) and commercial sensors over time (a), and the correlation between capacitance readings of MSMS and commercial sensors in the first 6 days (b).
Figure 7. MSMS sensors and commercial sensors under the water shock tests in the middle depth (a) and in the deep depth (b).
Figure 8. Soil moisture profiles obtained by MSMS sensors and commercial sensors in the middle and deep locations under different weather conditions.
Figure 9. The correlation between MSMS resistance readings and soil moisture in the lab validation tests.
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