受盐害的土壤课件

Salt-affectedSoils1.通常發生於semiaridandaridregions∵annualprecipitation<evapotranspiration2.Naturalsourcesofsoilsalinitya)Mineralweatheringb)Fossilsaltsc)Atmosphericprecipitation3.LocalsaltaccumulationSoilsinlow-lyingareas

EvaporationCapillaryrisewatertableSalt-affectedSoils1.通常發生於semi14.HumanActivitiesSaltsfromareasofover-irrigationaccumulateinpoorlydrainedareas.Relativelysalineirrigationwaterareused.Oil-fielddevelopment,waste-spreadingoperation,andcropfertilization4.HumanActivities2受盐害的土壤课件3灌溉水質1.TotalDissolvedSolids(TDS)大部分之灌溉用水TDS<1000mg‧L-12.ElectricalConductivity(EC)C(conductance)(mho)=C=LL(specificconductance)(mho/cm)1S(Siemen)=1mho1dS‧m-1=1mmho/cm1RResistance(ohm)Addsoln.AreaA灌溉水質1.TotalDissolvedSolids(43.WaterQualityRelations(a)TDS(mg/L)≈EC(dS‧m-1)×640(b)Sumofcationsoranions(mmole(+or-)‧L-1)≈EC(dS‧m-1)×10(c)OP(bars)≈EC(dS‧m-1)×(-0.36)(d)Hardness=[Ca2++Mg2+]Alkalinity=[HCO3-+CO32-]3.WaterQualityRelations5SodiumHazard1.Irrigationwater(HighNacontent)highESPofsoilSoilcrustbadlyandswellordispersegreatlydecreasingthehydraulicconductivityor

permeabilityofsoiltowater2.為何不以Naconcentration直接來表示？不能表示出ESP.因為ESP之決定不僅在於Na+在soln.之濃度，而是在於Na+和Ca2+、Mg2+爭取exch.sites。3.SAR(sodiumadsorptionratio),U.S.SalinityLab.Conc.Unit:mmoles(+)/L來表示relativesodiumstatusofirrigationwaterandsoilsoln.SodiumHazard1.Irrigationwate6Conc.Unit:mmole/L＊assumeonlyNaandCainthesystem．Conc.Unit:mmole/L＊assume7ESR(ExchangeableSodiumRatio)=Exch.cationconc.Unit=mmole(+)/kg所以KG(Gaponexchangecoefficient):TherangeofKGiscommonly0.010~0.015(L/mmole)-1/2ESR(ExchangeableSodiumRatio8∵Ca2+andMg2+behavequitesimilar

同理ESR=KG‧SARIfconsideringNa+,Ca2+,Mg2+inthesystem∵Ca2+andMg2+behavequites9Unit:mmole(+)/LUnit:mmole(+)/L10BicarbonateHazardHighHCO3-conc.HighpHiron＆othermicronutrientsdeficiencyResidualsodiumcarbonate(RSC)

conc.unit=mmoles(+or-)/L

可用來predictthetendencyforcalciumcarbonatetoprecipitatefromhigh-bicarbonatewater.RSC>2.5hazardous1.25<RSC<2.5potentiallyhazardousRSC<1.25generallysafeEmpiricalbutworkedreasonablywellIncreasingSARofwaterBicarbonateHazardHighHCO3-c11項目限值項目限值pH值6.0~9.0鈷(Co)mg/L0.05電導度μmho/cm25℃750銅(Cu)mg/L0.2懸浮固體物mg/L100鉛(Pb)mg/L0.1氯化物(Cl-)mg/L175鋰(Li)mg/L2.5硫酸鹽(SO4-2)mg/L200錳(Mn)mg/L2總氮量(T-N)mg/L1汞(Hg)mg/L0.005清潔劑(ABS)mg/L5鉬(Mo)mg/L0.01油脂mg/L5鎳(Ni)mg/L0.5鋁(Al)mg/L5硒(Se)mg/L0.02砷(As)mg/L1釩(V)mg/L10鈹(Be)mg/L0.5鋅(Zn)mg/L2硼(B)mg/L0.75鈉吸著率(SAR)6鎘(Cd)mg/L0.01殘餘碳酸鈉RCS(meq/L)2.5鉻(總)(Cr)mg/L0.1水溫℃35表3.1台灣省灌溉用水水質標準(67.7.5府建水字第59931號公告)附註：天然之水質若超過本標準之限值，得不受本標準之限制。項目限值項目限值pH12CharacterizationofSalt-affectedSoils1.Na-status(i)ESP(ExchangeableSodiumPercent)

直接測定ESP費時麻煩，且常有誤差CharacterizationofSalt-affec13(ii)SAR(SodiumAdsorptionRatio)SoilSoln.做為exch.-Nastatus之indexConc.單位：mmoles(+)/L(ii)SAR(SodiumAdsorptionRa14受盐害的土壤课件15Effectsofsaltsonsoilsandplants1.Maineffectonplants—OsmoticEffectWaterSemipermeablemembraneHighsaltconc.Effectsofsaltsonsoilsand16OutsidethemembraneHighsaltOsmoticpotential愈負Waterpotential愈負Difficultto

extractwaterOsmoticadjustmentProductionoforganicacidsorupdateofsalts使osmoticpotential愈負

waterpotential愈負然而消耗energy，並發生葉組織細胞不斷之分裂但不增長之現象PossibletocontinuouslyobtainwaterWaterpotentialInsidethemembraneOutsidethemembraneHighsalt172.Specific-ioneffectsPlantsaresensitivetospecificionsinirrigationwaterorsoilsoln.Boron,Chloride,ESPEffect3.Nutritionalimbalancese.g.bicarbonatetoxicity是由於highpH引起iron或其他micronutrients之deficiency,而不是bicarbonate直接引起之effect.

2.Specific-ioneffects18OthertoxicSolutesB,Li,NaandClB(Boron)缺乏～毒害之間只相差afewmg/LOthertoxicSolutes19受盐害的土壤课件20LeachingRequirement(LR)Ddw:AmountofdrainagewaterDiw:AmountofirrigationwaterECiw:ElectricalconductivityofirrigationwaterECdw:Electricalconductivityofdrainagewater為了維持Saltbalance(Saltentering=Saltleaching)所需之Leachingfraction(假設nosaltpropitiation,nosaltdissolvedfromsoilminerals,andnosalttakenupbythecrop)LeachingRequirement(LR)Ddw:21Ddw‧ECdw=Diw‧ECiwECdw(allowableECofthesaturationextract)canbeobtainedfromexistingsalttolerancedata(Table9.2).e.g.SoybeanECdw≦5.5ds‧m-1at25℃Ddw‧ECdw=Diw‧ECiw22受盐害的土壤课件23Reclamation1Saline,non-sodicsoilsLeachingponding-inefficientbasin-furrowmethodReclamation1Saline,non-sodi24Reclamation2Saline-SodicSoils;Sodicsoilsa)DecreaseESP

applicationofgypsum(CaSO4‧2H2O)

ortillage(深耕)bringsubsoillimetothesurface對calcareous-sodicsoils施用Sb)LeachingReclamation2Saline-S