soil tesng - ecological farming...adjus)ng soil ph • most crops can handle a wide range in soil...

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