Soil solution electrical conductivity measurements using different dielectric techniques

摘要: Accurate measurements of soil solution electrical conductivity (or.) are needed in various applications. One recently developed technique that measures sigma(w) is the Sigma Probe (SP). The SP supposed to give accurate readings only-slightly dependent on water content (theta) and type. To test performance SP, it was compared with another dielectric technique, time domain reflectometry (TDR). Both techniques utilize constant (K-a) bulk (sigma(a)) estimate sigma(w). Measurements were obtained a laboratory experiment using nine different types theta range 0.05 0.50 m(3) m(-3). In each type, three used (approximately 0.3, 1.2, 3.0 dS m(-1)). linear sigma(w)-sigma(a)-theta model by contains only one specific parameter (K-0) Using this model, over encountered 0, whereas TDR estimation calculated same typically increased at K-a values below 10 15. default K-0 value 4.1 gave 20% true when > 1 m(-1). error for or, lower than m(-1) can be much larger except sandy soils. conventional more all theta, root mean square errors about 50% readings. However, requires parameters have during calibration experiment. (Less)