」 ．　 B’ac ．　 fXgr． ，　 Kyss｝｝u　｛一」’Riv． ，　 45　（1） ，　 277－287　（2eOO） Meas皿ing the瞬eトAverage　Vo1㎜etric　Water　Content血the Uppermost 5　cm　of　S　oil　Using　Printed　Circuit

New｝y designed printed circuit board TDR probes （PCBPs ） were rnade ， and they were ca難bra£磁by沁d◎or exper㎞ent ． A regression e（茎撒t韮（）R罫or estima麺ng the volumetr量 。 wat愈r cOぎ｝te雛市◎1戦撫e（鮭e垂ec麺 。 c◎嚢s蝕も搬eas疑red with the PCBP響asごeもer臨ed ， w藪。｝｝is繊mosも も熱¢sa撚a asもhe we鼓一㎞◎照TOPゴs e（茎鷺山糠く）捻wh¢繋も難愈＄0嚢圭s raもher weもW罎eもhe（欝er奪難C¢ bec◎憩es玉arger as the s◎難顧es ． The PCBP w畿s（沁s顧¢dも◎raeasureもhe average waもer cQ瓢命蕊 over a soil layer 5 cin thick because tl”te thickness of soil layer invelved in measuring water eontent by rnicrowave remote sensing is several centimeters ． A comparison experirnent of raeasurements with PCBPs and those by microwave remote sensing was condueted in an arid area in the northwest of China ． The results of tr’ris experiment show that the newly desigried TII’）R probe is promising as the sensor to get ground trLith of the surface wetness ． This paper descri，bes oniy the calibration of probes and the ， observations taken using them