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Comparison of nuclear and capacitance‐based soil water measuring techniques in salt‐affected soils
Author(s) -
AlAin F.,
Attar J.,
Hussein F.,
Heng L. K.
Publication year - 2009
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/j.1475-2743.2009.00246.x
Subject(s) - gravimetric analysis , soil water , water content , calibration , soil science , calibration curve , soil test , moisture , capacitance probe , environmental science , analytical chemistry (journal) , chemistry , capacitance , mineralogy , environmental chemistry , geology , mathematics , detection limit , chromatography , geotechnical engineering , statistics , organic chemistry , electrode
A field calibration experiment was carried out on salt‐affected clayey soil in Syria, to compare the sensitivity to soil electrical conductivity (ECe), and bulk density ( ρ b ) of two instruments for estimating soil moisture: the neutron probe (NP) and the Diviner 2000 capacitance probe (CP). The results showed that the values of the correlation coefficient of the calibration were decreased when the ECe and ρ b values increased; this decrease was more pronounced for the Diviner 2000, indicating that it was more sensitive to ρ b and ECe than the NP. When only scaled frequency was used in the fitted equation, the Diviner 2000 in wet soil underestimated soil water content significantly at all depths, but especially in the top layer, by up to 0.09 cm 3 /cm 3 compared with gravimetric determinations. However, in dry soil, the Diviner 2000 overestimated the volumetric water content by up to 0.05 cm 3 /cm 3 in the top 15 cm, and by 0.03 cm 3 /cm 3 at 30‐45 cm depth. The performance of the neutron probe was better overall; using a factory calibration curve no significant differences were observed between NP estimates and the gravimetric values. Including both ρ b and ECe in the calibration equations improved the fits, although the regression coefficient ( R 2 ) for the Diviner 2000 remained low.