TY - JOUR
T1 - Time-domain and frequency-domain reflectometry type soil moisture sensor performance and soil temperature effects in fine- And coarse-textured soils
AU - Zhu, Yan
AU - Irmak, Suat
AU - Jhala, Amit J.
AU - Vuran, Mehmet C.
AU - Diotto, Adriano
N1 - Publisher Copyright:
© 2019 American Society of Agricultural and Biological Engineers.
PY - 2019
Y1 - 2019
N2 - The performances of six time-domain reflectometry (TDR) and frequency-domain reflectometry (FDR) type soil moisture sensors were investigated for measuring volumetric soil-water content ( θ v) in two different soil types. Soilspecific calibration equations were developed for each sensor using calibrated neutron probe-measured θ v. Sensors were also investigated for their performance response in measuring θ v to changes in soil temperature. The performance of all sensors was significantly different (P<0.05) than the neutron probe-measured θ v, with the same sensor also exhibiting variation between soils. In the silt loam soil, the 5TE sensor had the lowest root mean squared error (RMSE) of 0.041 m3/m3, indicating the best performance among all sensors investigated. The performance ranking of the other sensors from high performance to low was: TDR300 (High Clay Mode), CS616 (H) and 10HS, SM150, TDR300 (Standard Mode), and CS616 (V) (H: Horizontal installation and V: Vertical installation). In the loamy sand, the CS616 (H) performed best with an RMSE of 0.014 m3/m3 and the performance ranking of other sensors was: 5TE, CS616 (V), TDR300 (S), SM150, and 10HS. When θ v was near or above field capacity, the performance error of most sensors increased. Most sensors exhibited a linear response to increase in soil temperature. Most sensors exhibited substantial sensitivity to changes in soil temperature and the θ v response of the same sensor to high vs. normal soil temperatures differed significantly between the soils. All sensors underestimated θ v in high temperature range in both soils. The ranking order of the magnitude of change in θ v in response to 1°C increase in soil temperature (from the lowest to the greatest impact of soil temperature on sensor performance) in silt loam soil was: SM150, 5TE, TDR300 (S), 10HS, CS620, CS616 (H), and CS616 (V). The ranking order from lower to higher sensitivity to soil temperature changes in loamy sand was: 10HS, CS616 (H), 5TE, CS616 (V), SM150, and TDR300 (S). When the data from all sensors and soils are pooled, the overall average of change in θ v for a 1°C increase in soil temperature was 0.21 m3/m3 in silt loam soil and -0.052 m3/m3 in loamy sand. When all TDR- and FDR-type sensors were pooled separately for both soils, the average change in θ v for a 1°C increase in soil temperature for the TDR- and FDR-type sensors was 0.1918 and -0.0273 m3/m3, respectively, indicating that overall TDRtype sensors are more sensitive to soil temperature changes than FDR-type sensors when measuring θ v .
AB - The performances of six time-domain reflectometry (TDR) and frequency-domain reflectometry (FDR) type soil moisture sensors were investigated for measuring volumetric soil-water content ( θ v) in two different soil types. Soilspecific calibration equations were developed for each sensor using calibrated neutron probe-measured θ v. Sensors were also investigated for their performance response in measuring θ v to changes in soil temperature. The performance of all sensors was significantly different (P<0.05) than the neutron probe-measured θ v, with the same sensor also exhibiting variation between soils. In the silt loam soil, the 5TE sensor had the lowest root mean squared error (RMSE) of 0.041 m3/m3, indicating the best performance among all sensors investigated. The performance ranking of the other sensors from high performance to low was: TDR300 (High Clay Mode), CS616 (H) and 10HS, SM150, TDR300 (Standard Mode), and CS616 (V) (H: Horizontal installation and V: Vertical installation). In the loamy sand, the CS616 (H) performed best with an RMSE of 0.014 m3/m3 and the performance ranking of other sensors was: 5TE, CS616 (V), TDR300 (S), SM150, and 10HS. When θ v was near or above field capacity, the performance error of most sensors increased. Most sensors exhibited a linear response to increase in soil temperature. Most sensors exhibited substantial sensitivity to changes in soil temperature and the θ v response of the same sensor to high vs. normal soil temperatures differed significantly between the soils. All sensors underestimated θ v in high temperature range in both soils. The ranking order of the magnitude of change in θ v in response to 1°C increase in soil temperature (from the lowest to the greatest impact of soil temperature on sensor performance) in silt loam soil was: SM150, 5TE, TDR300 (S), 10HS, CS620, CS616 (H), and CS616 (V). The ranking order from lower to higher sensitivity to soil temperature changes in loamy sand was: 10HS, CS616 (H), 5TE, CS616 (V), SM150, and TDR300 (S). When the data from all sensors and soils are pooled, the overall average of change in θ v for a 1°C increase in soil temperature was 0.21 m3/m3 in silt loam soil and -0.052 m3/m3 in loamy sand. When all TDR- and FDR-type sensors were pooled separately for both soils, the average change in θ v for a 1°C increase in soil temperature for the TDR- and FDR-type sensors was 0.1918 and -0.0273 m3/m3, respectively, indicating that overall TDRtype sensors are more sensitive to soil temperature changes than FDR-type sensors when measuring θ v .
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U2 - 10.13031/aea.12908
DO - 10.13031/aea.12908
M3 - Article
AN - SCOPUS:85071841100
SN - 0883-8542
VL - 35
SP - 117
EP - 134
JO - Applied Engineering in Agriculture
JF - Applied Engineering in Agriculture
IS - 2
ER -