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討吻鏃量畿購屎 隧攣薔慇汎輻鰊購‡童量晰櫻‡膊 埒檬辟鶴 はま".量杉鰊‡隆詭曝畿‡‡浴 囀 yγ 炸 塀‡
‡oot、 vater uptake and sOil water llow/which carry heatand variOus substances′ are caused by the difference inハ、″ater Potential between the inv01ved llledia Microbial

during evaporation′ andく ‑05° C undereeze/thaw conditions′ with no disturll・bance Of mOisture or the therllnal envi―

activity in soils and Po｀ Vder alsO depends on the water Poten―

ronment The indings suggestthat sOiltial lt is fundamentally important to evaluate、 ハ″
ater Potential
in dry lnedia for research on、 vilting and Plant gro、 へ/th′ water、vater potential in frozen sOil requires
tillle to reach equilibrium after a temperature change andinduces nOn― equilibrium water llow during soil freezing

and nutrient managementin arid areas′soil salinization dur―ing evaporation′ and grain storage Furtherlllore′ estimatingwater potential in relatively dry soil is required in the devel

opment of accurate soil hydraulic conductivity lnodels

under ield cOnditions Additionally/a combinatiOn Of other

ヤVhen soilis exPoSed to subzerO temperatures′ most ofthe
ハ、/ater in the soil POreS freezes/butsOme remains unfrozenヱ ヽdecrease in unfrozen water with temperature produces a dry―like envirOnment′ resulting in iOぃ ′er soil water potential infrozen sOil TherefOre′ measuring water potential in relativelydry(frOzen)soiliS alsO important to design ellective use ofcold regions and tO investigate energy and heat balancesin the cryosphere′ which Play key r01es in g10bal climatechangelf sampling is available′

FINEDEl´ √is a Po、 verful and PrOSPectiVe senso↓ but
further studies are needed ofits use in long― terll■ lnonitoring

allnOst all ranges Of soil v̀ater Po―

tential can be llleasured by combined use Of the falling― headand Pressure Plate lllethods and equilibratiOn over a salt
solution HO、 eveL a″ small′ ′sensor is required to rnOnitor

sensors is still required to llleasure all sOil water potential

ranges This future apPliCation、 ハ″ould lnake it possible toclarify、 へrater POtentialin environments in which it has neverbeen lneasured and improve numerical models and、 へ/atermanagementin various ields
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reねtiveヶdryθρσa″ねs So″ Sc∴ρρ り4ノl「Soὸerハm」 ̀/a/わ76,7938‑79イ 5Иθ″めe″〃a月 吹〕
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the ever― changing water potential at PartiCular Observation

Points Recent PrOgreSS in sensor technology is remarkable′
as the llneasurement range of tensiometers has been extended
to about‑200 kPa SensOrs that rneasure the dielectric cOn―
stant or heat dissipation Of a POrouS ll■

atrix in equilibriumwith surrOunding soil are available′ and they can estimate
へ、″
ater potential fron■ ‑10 to‑2500 kPa′ but their accuracy andreSPOnse tilnes need to be improved
換ater Potentialin dry soil can also be estimated from therelative hun■ idity of、 ハ/ater vaPor in equilibrium with soil

water Techno10gy based on dew POint measurement using achilled inirror is exceptional from the viewpoint of accuracy

and resPOnse tilne HoweveL current chilled inirror potential
meters require a sampling chamber and′ thus′ cannot directly
monitor temPoral Changes in、 へ
rater Potential in sOil、 へ/ithwater flo、 へ/Azbil COrPOratiOn(TokyO/Japan)deVe10Ped a finger―
sized chilled lllirror hygrometeし called the FINEDE櫂 i、 へ/hichis small′dOes nOtrequire a samPling Chambet and can beplaced directly in POrOuS Inedia ln the November― Decen、
ber 2012 issue of the Sο

ノ7 Sε た″εa Sο ε′ス″θ″た′ルタ′″′7′

̀lyげresearchers used FINEDE1/V to lnonitor soil water potential

under variOus conditions FINEDEVV quickly and accurately
measured soil water potentials at<‑500 kPa in sOil undernear― equilibriun■ cOnditions′ く‑1000 kPa v√ ith、 vater now

doi:102134/csa201 3‑58‑1‑5」anuary 2013ろsル /

̀ゎatsc′eη cesocプ e″ es O■9/pυ わ″
car ons/soos到/aわ Sク lacFs/76/6/7938

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