Best Management Practices (BMPs) and Water Quality...
Transcript of Best Management Practices (BMPs) and Water Quality...
Best Management Practices (BMPs) and Water Quality Parameters of Selected Farms Located in the Arroyo Colorado Watershed
BMPs Implemented at Demonstration Sites• Croprotation• Cropresiduemanagement• NutrientManagement• PestManagement• IrrigationLandLeveling• IrrigationManagement• Irrigationwithpoly-pipe• Subsurfacedrainage• Vegetationfilterstrips
Agriculture in the Arroyo Colorado Watershed
ExcesswaterfromvariouslandscapeactivitiesintheLowerRioGrandeValleyaredrainedthroughtheArroyoColoradoeventuallyemptyingintothelowerLagunaMadre.TheLagunaAtascosaNationalWildlifeRefugeandseveralcountyandcityparksarelocatedwithintheArroyoColoradowatershed.Thewatershedisalsothehabitatofseveralsemi-tropicalplantsandanimalspecies.TheArroyoColoradoalsoboastsmanyrecreationalopportunitiesandattractsalargenumberoftouristsannually.Agriculture,municipalandindustrialactivitiesareallcontributorstowaterqualityissuesandimpairmentsintheArroyoColoradowatershed.Themainconcerncomingfromagriculturearechemicalssuchasfertilizersandpesticidesthatcanbecarriedwiththeirrigationwaterthroughrunoffanddeeppercolation.AgriculturalproducerscanimprovethewaterqualityoftheArroyoColoradobyimplementingbestmanagementpractices(BMPs)thatreducenonpointsource(NPS)pollutionfromagriculturallands.Severaldemonstrations,onefurtherdescribedbelow,havebeen
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developedsince2006tocharacterizethewaterqualityofirrigationandrunoffwaterandtoevaluatetheeffectivenessofBMPsonwaterqualityatthefieldandsub-watershedlevel.TheseactivitieshavebeenconductedinanefforttoimplementtheArroyoColoradoWatershedProtectionPlanandachieveitsgoalsofreducingpollutionfromvarioussources,oneofthosebeingagriculture.
ObjectivesOneofthemainsourcesofpollutionarethenutrientloadingsfromagriculturalrunoffandleachates;therefore,astudyfocusedonidentifyingtheeffectofagriculturalmanagementpracticesonNPSpollutionfromsurfaceirrigatedfarmsintheArroyoColoradowatershedwasinitiated.Theobjectiveofthestudywastoobtainwaterqualityinformation(parametersincluding:totaldissolvedsolids,nitratesandnitrites,orthophosphatephosphorus,totalphosphorus,andtotalKjeldahlnitrogen)ofirrigationwaterrunoffandgroundwaterinsixagriculturalfieldsduringthe2009and2010growingseasons.
Figure1:Irrigationpolypipeutilizedduringanirrigationevent
Best Management Practices (BMPs) and Water Quality Parameters of Selected Farms located in the Arroyo Colorado Watershed
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ResultsThepredominantirrigationsystemintheLowerRioGrandeValleyissurfaceirrigation.TheprimaryBMPsadoptedbyirrigatingfarmersintheArroyoColoradowatershedareconservationcroprotation,irrigationlandleveling,theuseofpoly-pipeandnutrientmanagement.Duringthisprojectonlyonesitehadfilterstripsatthelowerendoftherowswhichreceivedirrigationrunoff.Themainresultsofthisstudyarelistedbelow.
1. Theresultsindicatedthattheirrigationwateralreadycontainedhighconcentrationsofnitrates,nitrites,orthophosphates,totalphosphorusandtotalKjeldahlnitrogen.Also,theseconcentrationsvariedfromirrigationtoirrigation.
2. Thegainsofnitrates,nitritesandtotalKjeldahlnitrogenloadingsfromthefieldsweresmall.Theactivitythatresultedinthehighestinfluenceonnutrientloadingswastheamountofrunoff.Thiscouldbereducedthroughimprovedirrigationmanagement.
3. Nutrientloadingsduetoorthophosphatesandtotalphosphoruswereextremelylowforallsitesduringbothyears,andtheseloadingswerealsoinfluencedbytheamountofrunoff.Hightotaldissolvedsolidscouldhaveresultedfromhigherfurrowflow-ratesthatproduceincreasederosionandtransportofsediments.Thesehigherflowratesalsoresultinhighernutrientloadingsoforthophosphatesandtotalphosphorus.Theuseofpoly-pipecanreduceerosion,facilitateirrigationmanagementandmayhaveaninfluenceonorthophosphatesandtotalphosphorus.
4. Thenutrientvalueswithingroundwaterfluctuatedfromyeartoyearandfromirrigationtoirrigation,buttheyweregenerallylow.ThefewsitesthathadnutrientmanagementimplementedasaBMPwerethesitesthathadsomeofthelowestnutrientvaluesingroundwater.
Figure2:Runoffresultingfromanirrigationeventbeingmeasured.
RecommendationsProducerscanimplementmultipleBMPstoprotectthewaterqualityoftheArroyoColorado.ThecombinationofmultiplepracticescancreateagreaterimpactofnutrientreductionstotheArroyoColorado.Somepracticessuchaslandlevelingwithsomegradeandtheuseofpoly-pipefacilitateirrigationmanagementandthus,haveanimpactonimprovingyieldsandprofits.ThetwoBMPsthatreducednutrientrunoffthemostwerenutrientmanagementandirrigationmanagement.Nutrientmanagementtypicallyconsistsofapplyingfertilizerataspecificrateaccordingtoasoilanalysistest.Irrigationmanagementincludescontrollingthetotalamountofwaterappliedtothelandfocusingonusingnon-erosiveflow-rates,therebyreducingrunoff.
ThisprojectwasfundedbyaCleanWaterAct§319(h)grantthroughtheUnitedStatesEnvironmentalProtectionAgencyadministeredbytheTexasStateSoilandWaterConservationBoard.
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