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SoilTes)ng
• Tomonitorlong-termchangesandtrendsinyoursoil
• Todetermineiftherearedeficienciesand/ortoxici)esinthesoilthatneedtobeaddressed
• Fullsoiltestsdonebylaboratories§ Thesearegenerallycompleteanalyses
• Quicksoiltests§ Thesearespecificteststohelpmakedecisionsonfer)liza)on–themostcommonbeingthesoilnitratetest
SoilTes)ng• Itisimportanttotakeagoodsample• Takefrommul)pleloca)ons• Beawareofdifferencesinsoil(texture,etc)• Takearepresenta)vesamplefromthetopfoot(shovelslice,soilprobe,etc)
• BecarefultonotoverrepresentsoilfromthetopfewinchesasitishigherinorganicmaIerandfer)lity
• Mixthoroughly
Howquicklydosoiltestvalueschange?
BoIomline:§ Itisagoodideatodoafullfer)litytestevery2-3years,unlessamendmentsareused
§ Rapidly(withinweeks)-NO3-N§ Moderately(withinayear)-pH,salinity§ Slowly(>ayear)-mostfer)lityparameters
UnderstandingSoilTestAnalyses
Organic matter
Total N
Estimated N release
NH4-N
NO3-N
Phosphorus (PPM)
Sample ID pH (%) (%) (lb/acre) (PPM) (PPM) Bray Olsen Smith Block 7 7.1 1.2 0.06 36 2 3 3 8 Jones Block 2-N 7.7 0.7 0.04 21 1 8 31 23 Miller Block 4 6.0 0.8 0.04 24 3 22 54 32 Ruiz Block 1W 6.8 1.6 0.09 48 1 16 170 114
Sacramento Valley
San Joaquin Valley
Santa Maria Valley
Salinas Valley
Characteris)csofsomeCaliforniasoils:
Sample ID Soil texture Smith Block 7 loam Jones Block 2-N silty clay loam Miller Block 4 sandy loam Ruiz Block 1W clay loam
Organic matter
Total N
Estimated N release
NH4-N
NO3-N
Phosphorus (PPM)
Sample ID pH (%) (%) (lb/acre) (PPM) (PPM) Bray Olsen Smith Block 7 7.1 1.2 0.06 36 2 3 3 8 Jones Block 2-N 7.7 0.7 0.04 21 1 8 31 23 Miller Block 4 6.0 0.8 0.04 24 3 22 54 32 Ruiz Block 1W 6.8 1.6 0.09 48 1 16 170 114
SoilpH:
Saturatedpasteextract§ Manyvegetablecrops
growwelloverarangeofpH’s
§ Processingtomatoesforinstance,dowellfrom6.3to8.0
§ AtlowpH’s(<4.5)toomuchmanganesebecomesavailableandcanbetoxic
Manganesetoxicity
Adjus)ngSoilpH• MostcropscanhandleawiderangeinsoilpH’s
• Nitrogenfer)liza)ontendstoreducesoilpH• Brassica’sneedsoilpH>7.3toreduceissueswithclubroot
• IfyouneedtoincreasethepH,limeisused,butothermaterialssuchaswoodasheswillincreasethesoilpH
• Also,bicarbonateinirriga)onwaterraisessoilpH
• ElementalsulfurisusedtolowersoilpH
DesiredpHchange
PoundsofCaCO3equivalentperacre
in6”depth sand sandyloam
loam siltloam
clayloam
4.0to6.5 2,600 5,000 7,000 8,400 10,0004.5to6.5 2,200 4,200 5,800 7,000 8,4005.0to6.5 1,800 3,400 4,600 5,600 6,6005.5to6.5 1,200 2,600 3,400 4,000 4,6006.0to6.5 600 1,400 1,800 2,200 2,400
RaisingsoilpHwithlime(calciumcarbonate)
Resultsaffectedbysoiltextureandthelimingmaterial
Organic matter
Total N
Estimated N release
NH4-N
NO3-N
Phosphorus (PPM)
Sample ID pH (%) (%) (lb/acre) (PPM) (PPM) Bray Olsen Smith Block 7 7.1 1.2 0.06 36 2 3 3 8 Jones Block 2-N 7.7 0.7 0.04 21 1 8 31 23 Miller Block 4 6.0 0.8 0.04 24 3 22 54 32 Ruiz Block 1W 6.8 1.6 0.09 48 1 16 170 114
SoilorganicmaIer(measuredcombus)onordiges)on):
SelectedSalinasValleySoilsSoilType %Organic
MaIerPercentClay
FineSandyLoam 0.95 12SandyLoam 1.15 18Loam 1.80 25Clayloam 2.37 36Siltloam 2.41 47
Organic matter
Total N
Estimated N release
NH4-N
NO3-N
Phosphorus (PPM)
Sample ID pH (%) (%) (lb/acre) (PPM) (PPM) Bray Olsen Smith Block 7 7.1 1.2 0.06 36 2 3 3 8 Jones Block 2-N 7.7 0.7 0.04 21 1 8 31 23 Miller Block 4 6.0 0.8 0.04 24 3 22 54 32 Ruiz Block 1W 6.8 1.6 0.09 48 1 16 170 114
SoilorganicmaIer≈58%C;≈7%N;C:Nra)o≈10:1to12:1
SalinasValleySoilsComparison
Organic matter
Total N
Estimated N release
NH4-N
NO3-N
Phosphorus (PPM)
Sample ID pH (%) (%) (lb/acre) (PPM) (PPM) Bray Olsen Smith Block 7 7.1 1.2 0.06 36 2 3 3 8 Jones Block 2-N 7.7 0.7 0.04 21 1 8 31 23 Miller Block 4 6.0 0.8 0.04 24 3 22 54 32 Ruiz Block 1W 6.8 1.6 0.09 48 1 16 170 114
Soilbuildingprac)cesthatincreasethelevelsofsoilorganicmaIerincreasetheamountofNavailabletocropsbyincreasingthetotalamountofNavailableformineraliza)onSomelabswillprovidean‘Es)matedNrelease’§ Itisnotmeasured,butcalculatedfromeitherorganicmaIerorsoiltotalN
§ Differentlabsmayusedifferentformulasforthiscalcula)on
SoilNmineraliza)onpoten)al:
NRelease(lbsN/A/day)inSalinas
FromPatriciaLazicki
Organic matter
Total N
Estimated N release
NH4-N
NO3-N
Phosphorus (PPM)
Sample ID pH (%) (%) (lb/acre) (PPM) (PPM) Bray Olsen Smith Block 7 7.1 1.2 0.06 36 2 3 3 8 Jones Block 2-N 7.7 0.7 0.04 21 1 8 31 23 Miller Block 4 6.0 0.8 0.04 24 3 22 54 32 Ruiz Block 1W 6.8 1.6 0.09 48 1 16 170 114
SoilmineralN(nitrateandammonium):
§ NO3-NisthepredominateformofNinsoil§ NH4-Nlevelsarelowinthesummer(1-2ppm)§ NO3-Ncanchangesubstan)allyover)me,basedonsoil
temperature,irriga)onorrainfallamounts,soiltexture§ Giventhatnitratelevelscanchangequicklyitisbesttotestas
closetowhenyouwanttofer)lize§ Thenitratequicktestisagoodmethodtogetrapidlygeta
nitratevaluefromwhichyoucanmakefer)lizerdecisions§ Itiswidelyusedbyconven)onalgrowers,andislessusedby
organicgrowers
MakingaFer)lizerDecisionBasedonNitrogenReleasefromSoilOrganic
MaIer/PriorCropResidues• Soilbuildingprac)cescanhelpthesoiltoreleasegoodamountsofnitrogenforcrops
• Long-seasoncropscanbenefitfromthecumula)veamountofNreleasedfromthesoil
• Short-season,high-nitrogendemandingleafygreenvegetablesaremoredifficult,andmeasuringthepoolofresidualsoilnitratemaybeabeIerindica)onofavailablenitrogenforcropgrowth
RapidSoilNitrateTest
CaCl2extrac)on
Spinach Nitrogen Fertility Trial Clay Loam Soil
4-4-2 Fertilizer Planting
lbs N/A
Topdress
lbs N/A
Total
lbs N/A
Initial NO3-N
Fresh wt
tons/A 80 80 160 21 6.9 40 80 120 21 6.9 0 0 0 21 6.4
Spinach Nitrogen Fertility Trial Sandy loam soil
4-4-2 Fertilizer Planting
lbs N/A
Topdress
lbs N/A
Total
lbs N/A
Initial NO3-N
Fresh wt
tons/A 160 0 160 27 7.7 120 0 120 27 6.8 0 120 120 27 5.7
Nitrogen Content of Various Organic Fertilizers
Fertilizer Source Dry
2.5 Poultry 3 - 4 Seed meals
4 Poultry Manure + Meat and Bone Meals 12 - 13 Feather and blood meals
8 Meat and Bone 9 - 12 Guanos
Liquid 2 - 5 Fish waste 14 Hydrolyzed soybean
Organic matter
Total N
Estimated N release
NH4-N
NO3-N
Phosphorus (PPM)
Sample ID pH (%) (%) (lb/acre) (PPM) (PPM) Bray Olsen Smith Block 7 7.1 1.2 0.06 36 2 3 3 8 Jones Block 2-N 7.7 0.7 0.04 21 1 8 31 23 Miller Block 4 6.0 0.8 0.04 24 3 22 54 32 Ruiz Block 1W 6.8 1.6 0.09 48 1 16 170 114
Thesoilphosphorustestisgoodfordiagnosingdeficiencyinthesoil;itisalsogoodformonitoringlong-termtrendsinthesoil(whetheritisincreasing,duetomanureandcompostuseordecreasingandbecomingaproblem)CommonSoilTests:Olsen(bicarbonate)extrac)on:§ forsoil>pH6.0Bray(weakacid)extrac)on:§ forsoils<pH6.0
Soilphosphorus:
PhosphorusSoilTestValuesandYieldResponsetoPhosphorusFer)liza)on
Bicarbonate-extractablesoilP*Crop Yield
improvementlikely
Possibleyield
Improvement**
Yieldimprovement
unlikelyLeIuce/Celery <40 40-60 >60OtherCoolSeasonVegetables
<25 25-35 >35
Warmseasonvegetables
<15 15-25 >25
*ForBrayextrac)onmethodmul)plyvaluesby2.5**Par)cularlyincoldsoiltemperatures
SoilTestsareanIndexoftheAvailabilityofPhosphorus
• AvailablephosphorusisinanequilibriumwithinsolublemineralsandorganicmaIer
• TheOlsenandBraytestsgiveanindica)onofplant-availablephosphorus
• Theydonotgiveadirectmeasurementofactualpoundsperacreofphosphorusthatisavailable
%Pin Material organicform phosphateform
Feedlotmanure 25 75 Compostedmanure 16 84 Dairymanure 25 75 PoultryliIer 10 90 Swinemanure 9 91
ThePhosphorusinmanure(freshorcomposted)isequalinavailabilitytosynthe)cfer)lizer
HowavailableisPinanimalmanuresandcomposts?
Rockphosphateandbonemealareslowlyavailableinacidsoilsandareunavailablein
alkalinesoils
Organic Fertilizer Trials Salinas Valley Phosphate released from 4-4-2 Fertilizer
Perc
ent
Days after Planting Given soil pH’s in these evaluations (7.3-8.2), the phosphorus
in 4-4-2 that comes from bone meal, is not available to the crop and remains in the soil as an insoluble mineral
Exchangeable cations (PPM)
Percent cation saturation
Cation exchange capacity
Sample ID K Ca Mg Na K Ca Mg Na H (meq/100g) Smith Block 7 70 1147 992 272 1.2 37.3 53.8 7.7 0.0 15.4 Jones Block 2-N 331 4325 438 638 2.9 74.9 12.6 9.6 0.0 28.9 Miller Block 4 48 878 187 67 1.6 58.6 20.8 3.9 15.0 7.5 Ruiz Block 1W 416 2826 436 60 5.4 71.8 18.5 1.3 3.0 19.7
Ammoniumacetate(NH4Oac)extrac)on:§ 1.0NNH4
+displacesca)onsfromexchangesites
Exchangeablesoilca)ons:
10:1ra)oofsolu)ontosoil
SoilPotassiumDynamics
Usually<20PPM
50-400PPM
uptoseveralthousandPPM
§ Potassiumisotentakenupbymanyvegetablesingreaterquan))esthannitrogen
§ Onmanyfarmsmorepotassiumistakenoffthatisadded§ Potassiumvaluesinfer)lizersisreportedatK20(83%actualpotassium)
SourcesofPotassium
§ Minedminerals:§ Potassiumsulfate(40%actualpotassium),potassiumchloride(17%)
§ Greensand(1-5%)–lowsolubility§ Woodash(4%)§ Seaweed(upto2%)§ Compost(dependingonfeedstock,generallynomorethan2%)
§ Manures§ Chicken(2.5%)§ Cow(15-20%)
Organic Fertilizer Trials Salinas Valley Potassium released from 4-4-2 Fertilizer
Perc
ent
Days after Planting
PotassiumNutri)on
§ Issueswithpotassiumresultfromlowlevelsofpotassiuminthesoil
§ Also,‘fixa)on’resultsfromvermiculi)c(2:1)mineralscan
trapKionsininterlayersite
Potassiumdeficiencyonpeppers
§ Potassiumistakenupbyrootintercep)on§ Factorsthatreduceroo)ngortheamountofsoilthattherootsexploreaffectpotassiumnutri)on
§ Forinstance,intheearly1990’swhenpepperswerebeingtransi)onedtodripirriga)on,potassiumdeficiencybegantoshowupintheGilroyarea
§ Also,nematodeissuescanresultinpotassiumdeficiencysymptomsontheplant
Potassiumcropnutri)on
Exchangeable cations (PPM)
Percent cation saturation
Cation exchange capacity
Sample ID K Ca Mg Na K Ca Mg Na H (meq/100g) Smith Block 7 70 1147 992 272 1.2 37.3 53.8 7.7 0.0 15.4 Jones Block 2-N 331 4325 438 638 2.9 74.9 12.6 9.6 0.0 28.9 Miller Block 4 48 878 187 67 1.6 58.6 20.8 3.9 15.0 7.5 Ruiz Block 1W 416 2826 436 60 5.4 71.8 18.5 1.3 3.0 19.7
Exchangeablesoilca)ons:
§ Theca)onsarereleasedtothesoilsolu)onfromthenega)vechargesonclay,organicmaIerandsoilcolloids
§ Theyareinanequilibriumwiththesesources
Whataboutsoilca)onra)os?Manyproponentsof‘ideal’soilca)onra)os:• ≈10%H• 60-75%Ca• 10-20%Mg• 2-5%K• 1-5%Na
Inreality:§ highplantproduc)vityispossiblewithawiderangeofca)onra)os(lookatpartsoftheSacramentoValley–aroundDavis)
§ significantlymodifyingca)onra)osinsoilisusuallyprohibi)velyexpensive
Exchangeable cations (PPM)
Percent cation saturation
Cation exchange capacity
Sample ID K Ca Mg Na K Ca Mg Na H (meq/100g) Smith Block 7 70 1147 992 272 1.2 37.3 53.8 7.7 0.0 15.4 Jones Block 2-N 331 4325 438 638 2.9 74.9 12.6 9.6 0.0 28.9 Miller Block 4 48 878 187 67 1.6 58.6 20.8 3.9 15.0 7.5 Ruiz Block 1W 416 2826 436 60 5.4 71.8 18.5 1.3 3.0 19.7
§ InCaliforniasoils,calciumnormallydominatesthepercentofca)ons
§ Calciumdeficiencyisrareandmayonlybeseenverysandysoilsorhighlyacidicsoils
Exchangeablesoilca)ons:
§ TheSmith,block7isfromtheSacramentoValleyandthemagnesiumishigherinrela)ontocalcium(soilformedfromserpen)nerocks)
§ Thishasnotaffectedtheyieldofcropsbuthasaffectedquality:§ Tomatoeshavemorecolor
defectsandcantaloupestendtobesoter
YellowShoulder
PPMx4≈lb/acreintopfootofsoil
Evenassumingonlyhalfofexchangeableca)onsareplant-available,soilCaandMg
supplyistypicallyhigh
Exchangeable cations (PPM) Sample ID K Ca Mg Na
Smith Block 7 70 1147 992 272 Jones Block 2-N 331 4325 438 638 Miller Block 4 48 878 187 67 Ruiz Block 1W 416 2826 436 60
SoilCaandMgsupplynearlyalwaysmuchgreaterthancroprequirement
Actualcroprequirementsseldomexceed150lbCaand50lbMgperacre
Therearethingstoconsiderregardingsoilca)onra)os:
§ LowCa:Mgra)ocancausesoilstructuralproblems:hardsevng,lowwaterinfiltra)on
§ ExtremecasesofCa:Mgimbalanceresultinserpen)nesoilsinwildlandwhereonlyspecificplantsareadaptedandcangrow
CrustedSoil Serpen)neSoil
Physiological/WeatherInducedCalciumDeficiency
Cauliflower
Romaine
Tomato
Cabbage
Strawberry
Celery
Exchangeable cations (PPM)
Percent cation saturation
Cation exchange capacity
Sample ID K Ca Mg Na K Ca Mg Na H (meq/100g) Smith Block 7 70 1147 992 272 1.2 37.3 53.8 7.7 0.0 15.4 Jones Block 2-N 331 4325 438 638 2.9 74.9 12.6 9.6 0.0 28.9 Miller Block 4 48 878 187 67 1.6 58.6 20.8 3.9 15.0 7.5 Ruiz Block 1W 416 2826 436 60 5.4 71.8 18.5 1.3 3.0 19.7
Ca)onexchangecapacity(CEC):
§ TheCECisasumoftheca)ons*.Itisanindica)onofthesoiltextureandtheamountoforganicmaIer.
§ Thisisaninteres)ngindicatortoseeifitincreasesasorganicmaIerincreasesinyoursoilbuildingprocess
Sample ID Soil texture Smith Block 7 loam Jones Block 2-N silty clay loam Miller Block 4 sandy loam Ruiz Block 1W clay loam
Sulfur• SulfurisabundantinCaliforniasoils• Itcomesfrommineraliza)onfromorganicmaIer,atmosphericdeposi)on,infer)lizers,ingypsumandinirriga)onwater
• Itisimportanttoknowhowmuchsulfate(SO4-S)isintheirriga)onwatertobeIerunderstandhowmuchsulfurisavailabletothecrop
Soluble salts
Soluble cations (meq/liter)
Sodium adsorption
Chloride
Boron
Sample ID (dS/m) Ca Mg Na ratio (SAR) (PPM) (PPM) Smith Block 7 0.3 1.0 1.5 5.9 5.3 42 0.2 Jones Block 2-N 1.5 26.7 6.4 17.4 4.3 74 2.5 Miller Block 7 3.5 22.6 13.0 7.8 1.8 67 0.5 Ruiz Block 1W 1.4 7.8 3.4 3.6 1.5 28 0.3
Filteredextract
Soilsalinity:
‘Saturatedpasteextract’
MeasurementisElectricalConduc)vity(EC)§ conduc)vityispropor)onaltotheconcentra)onofions
Ca)ons:Ca2+Mg2+Na+(toxicion)
K+
Anions:Cl-(toxicion)SO4
2-
CO32-
HCO3-
NO3-
pH
SpecificIonToxicity:Na,Cl,Boron
Alkalinity:CO3
--+HCO3-
Cons)tuentsofsalinity
ECw=0.2 ECw=1 ECw=3 ECw=6
Osmotic Effect of Salts
Stun)ngisthefirstsymptomofsalinity
Specific Ion Toxicity
5.00 10.00 15.00 20.00 25.00 30.00 35.00Distance Across Bed (inches)
-45.00
-40.00
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
Dep
th (i
nche
s)
0.00.51.01.52.02.53.03.54.04.55.05.56.0
Drip Line Drip Line
Low Leaching Fraction under Drip in Strawberry
ECe (dS/m)
5 10 15 20 25 30 35Distance Across Bed (inches)
-45
-40
-35
-30
-25
-20
-15
-10
-5
Dep
th (i
nche
s)
0.00.51.01.52.02.53.03.54.04.55.05.56.0
Drip Line Drip Line
ECe(dS/m)
High Leaching Fraction under Drip in Strawberry
Soluble salts
Soluble cations (meq/liter)
Sodium adsorption
Chloride
Boron
Sample ID (dS/m) Ca Mg Na ratio (SAR) (PPM) (PPM) Smith Block 7 0.3 1.0 1.5 5.9 5.3 42 0.2 Jones Block 2-N 1.5 26.7 6.4 17.4 4.3 74 2.5 Miller Block 7 3.5 22.6 13.0 7.8 1.8 67 0.5 Ruiz Block 1W 1.4 7.8 3.4 3.6 1.5 28 0.3
Filteredextract
Source:ALPtes)ngprogram
Soilsalinity:
The1:1methodgivesdifferentresults‘Saturatedpasteextract’
Soluble salts
Soluble cations (meq/liter)
Sodium adsorption
Chloride
Boron
Sample ID (dS/m) Ca Mg Na ratio (SAR) (PPM) (PPM) Smith Block 7 0.3 1.0 1.5 5.9 5.3 42 0.2 Jones Block 2-N 1.5 26.7 6.4 17.4 4.3 74 2.5 Miller Block 7 3.5 22.6 13.0 7.8 1.8 67 0.5 Ruiz Block 1W 1.4 7.8 3.4 3.6 1.5 28 0.3
Valuesdifferinbothmagnitudeandra)ofromexchangeableca)onsbecause§ extractsaredifferent(deionizedwatervs.1MNH4Oac)§ propor)onsaredifferent§ unitsaredifferent
Solubleca)ons:
Soluble salts
Soluble cations (meq/liter)
Sodium adsorption
Chloride
Boron
Sample ID (dS/m) Ca Mg Na ratio (SAR) (PPM) (PPM) Smith Block 7 0.3 1.0 1.5 5.9 5.3 42 0.2 Jones Block 2-N 1.5 26.7 6.4 17.4 4.3 74 2.5 Miller Block 7 3.5 22.6 13.0 7.8 1.8 67 0.5 Ruiz Block 1W 1.4 7.8 3.4 3.6 1.5 28 0.3
√meqNa
(meqCa+meqMg)/2SAR=
Sodiumadsorp)onra)o(SAR):
Thesodiumabsorp)onra)omeasuresiftheadverseeffectofsodiumonwaterinfiltra)onandaera)oninthe
soilaremi)gatedbythepresenceofcalciumandmagnesiuminthesoil.WhentheSARra)oincreasesto12–15,seriousphysicalproper)esariseinthesoiland
plantshavetroubleabsorbingwater.
Soluble salts
Soluble cations (meq/liter)
Sodium adsorption
Chloride
Boron
Sample ID (dS/m) Ca Mg Na ratio (SAR) (PPM) (PPM) Smith Block 7 0.3 1.0 1.5 5.9 5.3 42 0.2 Jones Block 2-N 1.5 26.7 6.4 17.4 4.3 74 2.5 Miller Block 7 3.5 22.6 13.0 7.8 1.8 67 0.5 Ruiz Block 1W 1.4 7.8 3.4 3.6 1.5 28 0.3
PPMClmaybereportedasmeq/liter:35.5PPM=1.0meq/liter
Saturatedpastechloride:
ppm meq/liter Comment<70 <2.0 Generallysafeforallplants
70-140 2.0–3.9 Sensi)veplantsshowinjury(beans,onion,leIuce,carrot)
141-350 3.9–9.8 Moderatelytolerantplantsshowinjury(potato,alfalfa,squash)
>350 >9.8 Severeproblems(sugarbeets,barley)
Soluble salts
Soluble cations (meq/liter)
Sodium adsorption
Chloride
Boron
Sample ID (dS/m) Ca Mg Na ratio (SAR) (PPM) (PPM) Smith Block 7 0.3 1.0 1.5 5.9 5.3 42 0.2 Jones Block 2-N 1.5 26.7 6.4 17.4 4.3 74 2.5 Miller Block 7 3.5 22.6 13.0 7.8 1.8 67 0.5 Ruiz Block 1W 1.4 7.8 3.4 3.6 1.5 28 0.3
§ BorondeficiencyinCaliforniaisunusual§ Borontoxicityoccursincertainareas(e.g.somepartsofSanBenitoCounty)
§ Boroncontentofthewaterneedstobeevaluatedtoseeifitiscontribu)ngtotheissue
§ saturatedpasteBismostsuitedfortoxicityevalua)on
Saturatedpasteboron:
DTPA micronutrients (PPM) Soil texture (% by weight)
Sample ID Zinc (Zn)
Iron (Fe)
Manganese (Mn)
Copper (Cu)
sand
silt
clay
Smith Block 7 0.1 9.2 5.4 0.2 48 37 15 Jones Block 2-N 1.8 1.4 1.4 0.6 20 51 29 Miller Block 4 1.8 15.0 5.7 0.6 65 26 9 Ruiz Block 1W 2.0 15.4 13.4 0.9 31 35 34
§ DTPA(diethylenetriaminepentaace)cacid)isachela)ngagent
§ Theseelementsexistinmanychemicalcompoundsinsoil,ofvaryingsolubility
§ Theextractantsolu)onandmethodarestructuredtoextractmicronutrientslikelytobeplant-available
DTPAextractablemicronutrients:
PPM DeficiencylikelytooccurCopper 0.8-1.2 Organicsoils,sandsIron 5-15 HighsoilpH,veryhighZnand
Mn;carbonateinirriga)onwater
Manganese 2-10 HighsoilpHZinc 0.7-1.5 HighsoilpH,sandy/lowOM(cut
areas),veryhighavailablePinsoil
Cri)calrangesforsoilDTPAcopper,iron,manganeseandzinc:
Interpre)ngsoilmicronutrientlevels
Whydocommercialtes)nglabssome)mesgivedifferentresultsforthesamesoilsample?§ labsmayusedifferentanaly)caltechniques§ labsmayreportresultsindifferentunits
Electronicresource:
Whydocommercialtes)nglabssome)mesgivedifferentresultsforthesamesoilsample?§ thereisinherentvariabilityineachtestprocedure
Medianabsolutedevia)onpH 2%E.C. 15%‘soluble’ca)ons 20%OlsenorBrayP 15%Exchangeableca)ons 10%DTPAmicronutrients 15%NO3-N 10%OrganicmaIer 10%
NAPTprogram
Whydocommercialtes)nglabssome)mesgivedifferentresultsforthesamesoilsample?§ labaccuracymaydiffer
Organic Soil Fertility Short-Course February 12, 2019
ThankYouforYourA.en0on
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