Example: air traffic controller

Irrigation Water Quality Standards and Salinity Management ...

Irrigation Water QualityStandardsandSalinity ManagementStrategiesB-16674-03Ne arlyall waterscontain dis -solved saltsandtrac e ele ments ,manyof whichresultfromthenatural weatheringof theearth addition,drainagewaters fromirrigatedlandsandef fl uentfromcity sewageandindustrialwastewatercanim pactwater mostirrigationsit ua tio ns,theprimarywate r qual-ity concernis salinitylevels, sincesa lts can affe ct boththe soi l st ruc -tureandcropyi ever,anumberof tra ce elements arefoundin waterwhichcan limit nerally, salt is thoughtof asordinary tablesa lt (s odiumchlo -ride).Ho w-ev er , many types ofsa lts exi st and arecommonlyfoundin Texaswate rs (T abl e 1).

Irrigation Water Several different measurements are used to classify the suitability of water for irrigation, including EC iw, the total dissolved solids, ... cause saline soils are very soluble in water; therefore, leaching is usually quite effective in reclaim - ing these soils. Sodic soils (resulting from sodi -

Tags:

  Water, Irrigation, Saline, Irrigation water

Information

Domain:

Source:

Link to this page:

Please notify us if you found a problem with this document:

Other abuse

Transcription of Irrigation Water Quality Standards and Salinity Management ...

1 Irrigation Water QualityStandardsandSalinity ManagementStrategiesB-16674-03Ne arlyall waterscontain dis -solved saltsandtrac e ele ments ,manyof whichresultfromthenatural weatheringof theearth addition,drainagewaters fromirrigatedlandsandef fl uentfromcity sewageandindustrialwastewatercanim pactwater mostirrigationsit ua tio ns,theprimarywate r qual-ity concernis salinitylevels, sincesa lts can affe ct boththe soi l st ruc -tureandcropyi ever,anumberof tra ce elements arefoundin waterwhichcan limit nerally, salt is thoughtof asordinary tablesa lt (s odiumchlo -ride).Ho w-ev er , many types ofsa lts exi st and arecommonlyfoundin Texaswate rs (T abl e 1).

2 Most sal inityproblemsin agricul -tureres ul t directlyfromthesal tscarri ed in theirrigationwate at workis illustrat edin Fi gure1, which shows abe ake r of wa ter containinga sa ltconcent ra tionof 1 percent. Aswater ev aporate s, thedissolvedsa lts remain, res ultingin a sol u-tionwith a higher concentrati onof sa lt. The sameprocess oc cursin soil s. Sa lts as well as oth er di s-sol vedsubstances beginto accu -mulate as wa ter ev aporates fromthesurfac e and as cropswit :Units,TermsandSamplingNumerouspa ra me te rs are usedtode fineirri gat ionwa ter Quality , toasse ss sa linity ha zards,and tode te rmine appropriate ma nagementst ra tegies.

3 A complete Water quali-ty ana lysi s wil l inc ludethe det er -mi na ti on of:1) thetota l concentrationof sol u-bl e sa lt s,2) there la tiv e proportion of sodi-umto the other ca tions,3) thebi carbonate concent rat ionasre lated to theconcentrationofcalciumand magnesium, and3 Irr igationWaterQualityStandardsandSalinityM an ag ementGuyFi pps*Table 1. Ki ndsof saltsnormall y fou nd in irriga tionwaters,wi thch emi calsymbols andapp roxi-mate proportions of (L on geneck er andLyerly,1994)Che mical na meChemicalsymbolApproximateproportionof tot al sal t co ntentSo dium ch lor id eNaClModerateto largeSo dium su lfateNa2SO4 Moderate to la rgeCa lc ium chlor ideCaCl2 ModerateCa lc ium su lfate (gy psum )

4 CaSO42H2 OModerate to smallMa gn es iu m ch lo rid eMg Cl2 ModerateMa gn es iu m su lfateMg S04 Moderate to sma llPo tassi um chlo ri deKClSmallPo tassi um sulf ateK2SO4 Sma llSo dium bic arbon ateNaHC O3 Sma llCa lc ium carbon ateCaCO3 Very SmallSo dium ca rb onateNa2CO3 Tra ce to noneBo ra tesBO-3 Tra ce to noneNitr ate sNO-3 Sma ll to none1 Wat ers vary gr eatly in amoun ts an d ki nds of dissol ved sa lts. This wat er typi fie s many used for irrigationin Te xas.*AssociateProfessorandExtensionAgric ulturalEngineer,DepartmentofAgricultural Engineering,TheTexasA&MSystem,CollegeSta tion, ) the concentrationsof spe ci ficele me ountsan d combinationsofthese substancesdefinethe sui t-ability of Water forirrigationandthepotentialforpl ble2 definescommonparame -tersforanalyzingthesui ta bility ofwater forirrigationandpro videssomeus sa mplesforlaboratoryanalysis,ke ep in mindthatwaterfr omthesamesourcecanvaryin Quality wit h ,samplesshouldbe tes t-ed at intervalsthroughouttheyear,particularlyd uringthepot ent ial irrigationpe Water TestingLa b atTexasA&M Un iv ersitycan do acompletesalinityanalysis of irri -gat ionwateran d soilsamples.

5 Andwil l pro videa detaile d computerprintouton theint erpretationoftheres contact theLab at(979) SaltProblemsTwotypes of sa lt problemsexi stwhich areve ry different:thoseassociat ed with thetotal sa linit yand th os e ass ociated y be affe cte d onlybysa linityor by a combinationofbothsa linityand li nity HazardWa te r with highsalinityis toxicto pla ntsand poses asalinityhaz-ard. Soils with highlevels oftotalsal inityare sa lt in thesoilca n res ult in a physiologi-cal ,eventhoughthefieldappear s tohaveplentyof moisture,theplantswilt be ca usetherootsareunableto absorbthewater. Wa te rsa linityis us ua lly measured bytheTDS(t ota l dis solved solids)ortheEC (el ectric conducti vit y).

6 TDS is sometime s referre d to asthetot al sa li nit y and is me asuredor expresse d in parts pe r mill ion(ppm)or in the equival ent units ofmi lli gra mspe r lite r (mg/L).ECis actua ll y a meas urementofelect ric current and is re po rtedinoneof thre e possibleunitsasgiv en in Tabl e 2. Subscripts areused wi th thesymbolEC to iden-ti fy the source of thesam theele ctri c conductivityof the irri gat ionwat er. ECeis theelect ric conducti vi ty of thesoi l asme asure d in a soil sa mple (satu-rat ed ext rac t) ta ken fromtherootzone. ECdis thesoil sal ini ty ofthesatura te d ext rac t taken frombe lowtherootzone.

7 ECdis usedto det erminethesal ini ty of thedraina ge Water which leachesbe ure 1. Ef fect of wate r evapor ation on the concentration of salts in liter is grams ounces or about 1 of Sali ni ty Problemsaffectscan lead tosa lin it ypla ntssalinesoilha zar dconditionaffectscan lead tosodi umsoilssodic soilconditioningly imperviousto wate r pene-tra ti ne text ure d soils, espe-cia ll y thosehi gh in cla y, aremostsubjec t to thi s rtainame ndment s may be re qui redtoma int ain soils underhighSA lc iumand magnesium, if pre -se nt in thesoil in large enoughquantitie s, wi ll counter the effectsof the sodiumandhe lp ma int aingoodsoi l properti es.

8 Soluble sodium pe r cent(SSP)isalsoused to ev al uat e sodium de fined as the rationof sodiumin epm(equiva lentspermi ll ion)to thetota l cat ionepmmulti pli ed by Water with aSSPgre ater tha n 60 percentmayre sul t in sod iumacc um ul ati onstha t will causea bre akdown in thesoi l s physic al propert ie ,Tr aceElementsandOtherProblemsA number ofot he r substancesma y be foundin irri ga tion waterand can cause toxi c re act io ns inpla nts(T abl e 3). After sodium,chlorideandboronare of cert ain are as of Texas,boronconcent ra ti onsare exces-si ve ly hi gh andre nderwaterunsuita bleforirri ga tions.

9 Boroncan alsoacc umulate in the soi soi ls having anim bal anc e of calc iumand magne-si umma y also exhibit toxicsymptoms. Sulfa te sal ts affectse nsi tive cropsby lim it ingtheuptake of cal ciumand inc reasingtheads orptionof sodiumandpotass ium,re sultingin a di stur-ba ncein thecati onicba la ncewi thinthepla nt . The bi carbonateionin soi l solutionharms themi neral nut riti on of thepl antthroughit s effe cts on the upt akeand metabolis m of nut ri pot assi ummayint roducea ma gnesi umde fi ciencyand ironchlorosis. An imbalanceof magnesiumand pot as siummaybe toxic, but the effe cts of bothcan be re duced by hi gh calciumlev el 2.

10 Terms, units,an d us ef ul conversionsfo r understandin gwat er qualityanalysi s re linitya. ECel ect ri c conductivit ymm hos/cm mho s/cmdS /mb. TDStota l diss olv ed soli dsmg /LppmSodium Hazarda. SA Rsod ium adsor pti on ratio b. ESPex cha ng ea ble sodi um pe rcent age DeterminationSymbolUnit of measureAtomicweightConstituents(1 ) cat ionscal ci umCamol/m340. 1mag ne si umMgmol/m324. 3sodi umNamol/m323. 0pot assi umKmol/m339. 1(2 ) ani on sbicar bo nateHC O3mol/ m361. 0sul ph at eSO4mol/ m396. 1chl or ideClmol/m335. 5car bo nat eCO3mol/ m360. 0nit rat eNO3mg/ L62. 0 TraceElementsbor dS/ m = 1 mmho s/cm = 1000 mhos/cm1 mg/L = 1 pp mTD S (m g/ L) EC (dS/m)x 64 0 for EC < 5 dS/mTD S (m g/ L EC (dS/m)x 80 0for EC > 5 dS/mTD S (l bs/a c-ft) TDS (mg /L ) x ncen tr at ion (p pm) = Con cen tr at ion (mol /m3) tim es the atomicweightSu m of ca tions/a ni ons(m eq/ L) EC (d S/ m) x 10Ke ymg/L = milligrams per lite rppm = parts per milliondS/m = deci Siem en s per met er at 25 CSodium Haz ardIrri gationwa ter containing largeamountsof sodiumis of specia lconcerndueto sodium s ef fec tson thesoil andposesasodiumhazard.)


Related search queries