Nitrogen, phosphorus, calcium, and magnesium applied individually or as a slow release or controlled release fertilizer increase growth and yield and affect macronutrient and micronutrient concentration and content of field-grown tomato plants

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ContentslistsavailableatScienceDirect

Scientia

Horticulturae

j o u r n a l ho me p ag e :w w w . e l s e v i e r . c o m / l o c a t e / s c i h o r t i

Nitrogen,

phosphorus,

calcium,

and

magnesium

applied

individually

or

as

a

slow

release

or

controlled

release

fertilizer

increase

growth

and

yield

and

affect

macronutrient

and

micronutrient

concentration

and

content

of

ﬁeld-grown

tomato

plants

Janet

C. Cole

(Regents

Professor)

a,∗

_,

_Michael

_W.

_Smith

_(Regents

_Professor)

a

_,

Chad

J. Penn

(Former

Associate

Professor)

b

_,

_Becky

_S.

_Cheary

_(Senior

_{Agriculturist)}

a

_,

Kelley

J. Conaghan

(Former

undergraduate

student)

a

a_Department_of_Horticulture_and_Landscape_{Architecture,}_Oklahoma_State_University,₃₅₈_Ag_Hall,_Stillwater,_OK_74078-6027,_USA

b_Department_of_Plant_and_Soil_Sciences,_Oklahoma_State_University,₃₆₈_Ag_Hall,_Stillwater,_OK_74078-6028,_USA

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received30September2015

Receivedinrevisedform

15September2016

Accepted16September2016

Keywords:

Plantnutrition

Solanumlycopersicum

Magnesiumammoniumphosphate

Slowreleasefertilizer

a

b

s

t

r

a

c

t

TheU.S.EnvironmentalProtectionAgency(USEPA)hasrestrictedconcentratedanimalfeedingoperation (CAFO)releaseofwasteproductsintoU.S.waters.Thesewasteproductsmustbedisposedofusingbest managementpractices.Mostofthewasteisspreadoncropland,butsomeoperationshavefoundother creativeusesforwasteproducts.Useofaphosphorus(P)reductionsystemtoremovePfrom wastew-aterresultsinmagnesiumammoniumphosphate(MAP),aslowlysolublefertilizer.UsingaPreduction systemwillnoteliminatetheneedforlandapplicationofmanureandwastewater,butitreducesthe nutrientloadinthewastethatisappliedtherebymakingcompliancewithregulationseasier.Intheﬁrst yearofthisstudy,MAPwascomparedtoacontrolledreleasefertilizer(CRF)withasimilarnutrient ele-mentratioonplantgrowth,fruityield,nitrogen(N),P,potassium(K),calcium(Ca),magnesium(Mg), iron(Fe),manganese(Mn),andzinc(Zn)concentrationintomato(SolanumlycopersicumL.‘Mountain FreshPlus’)plantparts.Plantgrowthandfruitproductionweresimilarwiththetwofertilizers,butthe numberoftomatocullswasgreaterwitheitherfertilizerthanoncontrolplants.FoliarN,P,Ca,andMg concentrationdidnotdifferregardlessoffertilizertreatment.PlantsfertilizedwithCRFhadagreaterleaf KconcentrationthanthosefertilizedwithMAP,butfoliarKconcentrationdidnotdifferbetween fertil-izedandnonfertilizedplants.IronandMnconcentrationinabove-groundvegetativeplantparts(stems andleaves)didnotdifferregardlessoffertilizertreatment,butZnconcentrationincreasedlinearlyas CRFincreased.Inthesecondyear,MAP,eachoftheessentialelementscontainedinMAPseparately, andahandmixtureofeachoftheseelementswastestedfortheireffectontomatoplantgrowth,fruit yield,andtissueN,P,K,Ca,Mg,Fe,Mn,andZnconcentrationandcontent.Magnesiumammonium phos-phateandthehandmixtureoffertilizerresultedingreaterabove-groundbiomassexcludingfruitstem weightandfruityieldthananyoftheindividualnutrienttreatments.Calciumsulfateresultedinagreater numberandweightoftomatoesharvestedthanMAP.Nitrogenconcentrationdidnotdifferamongthe fertilizertreatmentsforroots,stems,orleaves,butNcontentwasgreaterinredfruitwiththehandmix offertilizerthanwithnofertilizerorwithammoniumsulfateorMgoxide.Inimmaturegreenfruitat terminationofthestudy,NcontentwasgreaterwithnofertilizerorCasulfatethanwithMAPortriple superphosphate(TSP).Phosphorus,K,andCaconcentrationsdidnotdifferamongfertilizertreatments foranytissuetested.Magnesiumconcentrationingreentomatoesdifferedamongfertilizertreatments suchthatMgconcentrationofgreentomatoesfromplantsfertilizedwithTSPwasgreaterthanMg con-centrationofgreentomatoesfertilizedwithammoniumsulfateorMgoxide.PhosphorusandKcontent ofgreenfruitdifferedamongfertilizertreatmentswithPandKconcentrationhighestingreenfruitfrom plantsfertilizedwithCasulfateandlowestingreenfruitfromplantsfertilizedwithMAPorTSP.

∗ Correspondingauthorat:DepartmentofHorticultureandLandscapeArchitecture,OklahomaStateUniversity,358AgHall,Stillwater,OK74078-6027,USA.

E-mailaddress:janet.cole@okstate.edu(J.C.Cole).

http://dx.doi.org/10.1016/j.scienta.2016.09.028

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IronandMnconcentrationsdidnotdifferamongfertilizertreatmentsforanytissuetested.Zinc concen-trationinleaveswasgreaterwhenplantswerefertilizedwithMAP,TSP,Casulfate,orMgoxidethan withammoniumsulfate.ZincconcentrationofgreenfruitwasgreaterwhenfertilizedwithMAPthan withthehandmix,CasulfateorMgoxide.Ironcontentwashighestingreenfruitfromplantsfertilized withTSPandlowestinplantsfertilizedwithammoniumsulfateorcontrolplants.Manganesecontentof leavesfromcontrolplantswasgreaterthanthatofplantsreceivingammoniumsulfatewhileredfruit fromplantsfertilizedwiththehandmixhadagreaterMncontentthanredfruitfromanyother treat-ment.FoliarZncontentwasgreaterinplantsfertilizedwithCasulfatethaninthosefertilizedwiththe handmix,ammoniumsulfate,orTSP.Incontrast,Zncontentofredfruitfertilizedwiththehandmixwas greaterthanforredfruitinanyothertreatment.GreenfruitfromcontrolplantsandthosereceivingMAP hadagreaterZncontentthanplantsfertilizedwiththehandmix,TSP,orMgoxide.Fertilizerapplication increasedFe,Mn,andZncontentofseveralplanttissues.Noneofthelabelsoffertilizersappliedstated thattheycontainedmicronutrients;however,smallamountsofcontaminationwerepossible.Differing micronutrientcontentsofvariousplanttissuesamongfertilizertreatmentswereprobablyassociatedwith otherelementsaffectingplantgrowthornutrientuptake.Thenutrientelementspresentinthevarious fertilizerswerenotalwaysthenutrientelementsaffectedintheplantslikelyduetoanotherelementthat mayhavelimitedplantgrowthornutrientuptake.

1. Introduction

In2003,theUSEPArevisedregulationsfor CAFOs. Withthis

revision,thenumberofCAFOsregulatedincreased,andnew

regu-lationsaddressedlandapplicationofmanurefromCAFOs(USEPA,

2003).To complywith USEPA regulations, CAFOs must have a

NationalPollutantDischargeEliminationSystemPermit. Oneof

thepermitrequirementsisdevelopmentofanutrientmanagement

plan.Thepurposeofthisplanistoreducetheamountofnutrients

leavingCAFOsitesthatmightpollutewaterways.Nodischargeof

manure,poultrylitter,orwastewaterfromaCAFOproductionarea

mayenterU.S.waters.Producersmustusebestmanagement

prac-ticestoeitherapplythemanure,which mayrequirelargeland

areas,orproducersmayuseinnovativetechnologiestoachieve

pollutantreductions.

Onewaytoreducetheamountofmanure,andthereforethe

landareaonwhichitmustbespread,istoprecipitateMAP(also

calledstruvite).ArecentlydevelopedPreductionsysteminvolves

wastewaterﬂowingthroughaﬂuidized-bedreactorcausingPto

precipitateasMAP(Rutherford,2010).PlantproducerscanuseMAP

asaslowlysolublefertilizerinproductionofcrops.Oneadvantage

ofusingslowlysolublefertilizercomparedtotraditionalhighly

sol-ublefertilizersisthatplantnutrientsarereleasedoveralongertime

periodthatmayormaynotcorrespondbetterwithplantneeds.

Becauseofslowernutrientrelease,nutrientsarelesslikelytoleach

throughthesoilproﬁlebelowplantrootsorbecarriedtowaterways

resultinginpotentialforpollutionofthosewaterways.

ManyhorticulturalcropproducersuseCRFs.Similartoslowly

solublefertilizers,CRFsreleasenutrientsoveralongertimeperiod

thanhighlysolublefertilizers,butthemechanismforthisslower

releaseisdifferentthanforslowlysolublefertilizers.Controlled

release fertilizers discharge nutrients slowly because they are

encapsulatedinasemipermeablepolymercovering.Abrahamand

Pillai (1996) noted that about 40 to 70% of applied urea was

losttotheenvironment,butlosseswerereducedbycoatingurea

withcopolymer of acrylamide.Environmental conditions affect

nutrientreleaseofslowlysolubleandCRFs.Slowlysoluble

fertil-izersrequiremoistureandsoilmicroorganismactivityfornutrient

release(Morganetal.,2009).Controlledreleasefertilizersdepend

ondiffusionthroughcoatingswhichismoistureandtemperature

dependent(Morganetal.,2009).Thuscoolordryperiodsmayresult

ininadequatenutrientreleasetosupportplantgrowthandhotor

wetconditionsmayresultinnutrientdischargefasterthanplant

uptake.

Nitrogen,P,K,Ca,andMgareessentialplantmacronutrients.

NitrateandammoniumarethemajorformsofNtakenupbyplants

(Barkerand Bryson,2007).Undernormal, aeratedconditionsin

soils,nitrateis thepredominantform ofN takenup byplants.

Nitrateisreadilymobileinplants,butitmustbereducedto

ammo-niumforsynthesisofproteinsandotherorganiccompounds.Plants

recycleNfromthecyclingofproteinsandothernitrogenous

com-poundsasammonium(BarkerandBryson,2007).Scholbergetal.

(2000)notedthatNconcentrationsinvarioustissuesoftomato

plantsvarythroughoutthegrowingseason.

ThetotalamountofsoilPisoftenmuchgreaterthantheamount

ofplantavailableP(TisdaleandNelson,1975).Themaintenanceof

asuitableconcentrationofPinthesoilsolutionforplantuptake

depends onthe relative rateof organicmatter decomposition,

and ontheability ofthesoil’sinorganicfractions toﬁxsoluble

orthophosphatesininsolubleorslightlysolubleforms. Addition

ofsolublephosphatefertilizerscanincreasetheamountofsoluble

orthophosphatesinthesoilsolutionforashorttime,butdepending

onsoilpH,Pquicklyreactswithiron,aluminum,orsilicateclays

andbecomesunavailableforplantuptake.

RehmandSchmitt(2002)notedthatKcanoccurin

unavail-able,slowlyavailable,orreadilyavailableformsin soils.Onlya

smallamountofslowlyavailableKisavailableforplantuptake

duringasinglegrowingseason.ReadilyavailableKisdissolvedin

thesoilsolutionandreadilytakenupbyplants.Potassiumuptake

isaffectedbysoilmoisturecontent,soilaerationandoxygenlevel,

soiltemperature,andcompetingions

Like K, Ca and Mg in soilsoriginatefrom decomposition of

bedrock and mineralsthat containthese elements(Tisdale and

Nelson,1975).Comparedtootherminerals,Caweathersrelatively

quicklyandcanbecomeunavailabletoplantsvialeachinginhighly

weathered(mature)soils(PilbeamandMorley,2007).

Magnesium deﬁciency symptoms may occur when Mg is

limited, but they may also be associated with an antagonistic

relationshipbetweenMgions(Mg2+₎_and_other_cations._The

com-petitionofMgwithothercationsforuptakerangesfromhighest

to lowest as follows: K>NH4+>Ca>Na (Mills and Jones, 1996;

Pe ˜nalosaetal.,1995).

Numerous fertilizer formulations provide plant

macronutri-ents individually or in combinationsto the soil.Application of

macronutrient fertilizers usually affects nutrient availability to

plants.Micronutrientsaregenerallypresentinsufﬁcientamounts

inmostsoils,buttheiravailabilitymaybelimitedduetoa

vari-etyofconditions.Mostmicronutrientsaremoreavailablewhen

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con-sequentlyavailability.Interactionswithotherelements,colloidal

organicmatter, soil moistureand temperature can have major

impactsonavailabilityoruptakeofcertainmicronutrients.In

addi-tion,non-targetorganismsimmobilizemicronutrientsandsmall

amountsarelostbyerosionandleaching.

TotalFecontentofsoilisoflittlevalueindiagnosingFe

deﬁcien-ciesinplants(TisdaleandNelson,1975).Soilconditionsthatleadto

FedeﬁciencyincludepHabove7,lowsoilmoistureandloworganic

mattercontent(FothandEllis,1997).Ironuptakecanbereduced

byhighconcentrationsofP,Mn,copper,nickelorZn(Tisdaleand

Nelson,1975).

Manganeseavailabilityfor plantuptakedecreasesassoilpH

increases.DivalentMnistheformabsorbedattherootsurfacecell

membrane.AssoilpHdecreases,theproportionofexchangeable

Mn2+_increases_dramatically₍_Bromﬁeld_et_al.,₁₉₈₃_)._Manganese

deﬁciencyislargelyduetohighsoilpH,butitcantoalesserextent

beinducedbyanimbalanceofotherelementssuchasCa,Mg,and

ferrousiron(TisdaleandNelson,1975).

SimilartoFeandMn,plantavailabilityofZndependsonsoilpH,

Pconcentration,organicmattercontentandadsorptionbyclays

(TisdaleandNelson,1975).TheamountofZnpresentinthesoil

isnotareliableindicatorofplantavailability.Zinc deﬁciencyis

commoninplantsgrowinginhighlyweatheredacidorcalcareous

soils(TrehanandSekhon,1977).Zincionscanbeimmobilizedin

organicmattersothat theybecomeunavailableforrootuptake

(Ballingeretal.,1966;Storey,1957).However,inmostsituations

theZncomplexwithcolloidalorganicmatterincreasesavailability

(FothandEllis,1997).HighconcentrationsofsoilPintensifyZn deﬁciency.

AdditionofN,P,K,Ca,andMgmustoccurfrequentlyenoughto

supplyplantneedsbymaintainingeachofthesenutrientsinthesoil

solution.BecauseslowlysolubleandCRFfertilizersrelease

nutri-entsovertime,theyreplenishnutrientsinthesoilsolutionasthose

nutrientsarereleasedfromthefertilizer.Presenceandavailability

ofadequateplantnutrientsarevitalforplantgrowthandfruit

pro-duction.Theobjectivesofthisstudyweretodetermine(1)ifthe

slowreleasefertilizer,MAP(precipitatedfromanimalwastewater

throughaﬂuidized-bedreactor)andaCRFwithasimilarnutrient

ratio,affectsplantgrowth,yieldandN,P,K,Ca,Mg,Fe,Mn,orZn

concentrationinﬁeld-growntomatoplantfoliage,and(2)theeffect

ofN,P,Ca,andMgaloneorincombinationasahandmixtureof

theindividualelementsortheslowreleasefertilizerMAPonplant

growth,yield,andtissueN,P,K,Ca,Mg,Fe,Mn,orZn

concentra-tionandcontentofﬁeld-growntomatoplants.Applyingelements

individuallyallowedevaluationofacriticalnutrientshortageofa

singleelementversussupplyingallelementsasinthecaseofMAP

orthemixture.

2. Materialsandmethods

2.1. Experiment1,magnesiumammoniumphosphateversus

controlledreleasefertilizer

2.1.1. Culturalpractices

‘MountainFreshPlus’tomatoseedlings(Gardner,1999,2002)

wereplantedintoaRenfrowloam(ﬁne,mixed,superactive,

ther-micUderticPaleustolls)soilatStillwater,OK(N36◦09.412,W97◦

01.788)on4May2011.Plantspacingwithinrowwas1.8mand

1.8mbetweenrows.Thisspacingwasusedtoassurethatfertilizer

treatmentswereuniquetoeachplantandnotreatmentinﬂuenced

adjacentfertilizertreatments.Thespacingalsoallowedfor easy

harvestoffruit.Plantingholesweredugwitha15-cm-diameter

augertoadepthofabout15cm.Plantswerehand-wateredwith

ahoseimmediatelyafterplantingandthenasneededuntildrip

irrigationwasinstalledon8May2011.Thenplantswerewatered

dailyat0700HRfor1handat1300HRfor1hwithdripirrigation

(62mlm−1min−1)untilthestudywasterminated.Airtemperature

wasmeasuredat30minintervalsusingdataloggers(WatchDog

1225,SpectrumTechnologies,Aurora,IL).Highandlow

tempera-turesweredeterminedforeachdayduringtheexperimentthen

averagedailymaximum/minimumtemperaturesof 35.4/21.4◦C

werecalculated.

Baskets constructed from woven ﬁeld fence (Red Brand;

Peoria, IL) with 10cm by 10cm spaces between the wires

were placed around each plant 48h after planting.

Bas-kets were 53.3cm in diameter and 122cm tall. Glyphosate

((N-phosphonomethyl)glycine, Eraser; Surrender brand, Control

Solutions,Pasadena,TX)wasapplied5June,2011at7.5gL−1a.i.

outsideofthebasketsforweedcontrol.Weedswerecontrolled

insideofthebasketsbyhandweeding.

2.1.2. Treatments

Asoiltestconductedpriortothestudyshowedthatthesitewas

lowinNandP,andrecommendedasingleapplicationof4.9gm−2N

andapplying12gm−2Pannually.Nofertilizerwasappliedpriorto

theexperimentalfertilizertreatments.Forplantsreceiving

fertil-izertreatments,fertilizerwasspreaduniformlyinthebottomof

theplantingholepriortoplantingtheplants.TheMAPfertilizer

(TerraPhos;KansasEnvironmentalManagementAssociates,Salina,

KS)consistedof4N-11.2P-0.4K(4N-26P2O5-0.5K2O)with8%Ca

and9%MgandFloricoteCRF(Floricote;Florikan,Sarasota,FL)was

10N-21P-0K(10N-49P2O5-0K2O).BothMAPandCRFwereapplied

at0,2.45,4.9,or9.8gm−2N.Theseapplicationratesprovided0,

2.7,5.5, or11.0gm−2P,respectivelywithMAPand0,5.1, 10.3,

or20.6gm−2,respectivelywithCRF.Themanufacturerestimated

completereleaseofnutrientsintheCRFwithin90dat26.6◦C.

2.1.3. Datacollection

Plant height and width (two perpendicular measurements)

weremeasured2,4,and8weeksafterplanting.Fruitwere

har-vesteddailyasredcolorappeared(breakerredstage).Fruitwere

gradedasediblefruitor consideredculls iftheyweredamaged

suchthattheywereunacceptableforthefreshmarket.Generally

damagewasduetofeedingbybirdsandotherwildlife.Fruitswere

countedandweigheddaily,includingweekends.

Above-groundplantpartswereharvested beginning29 Aug.

2011andseparatedintoimmaturetomatoesandstemswithleaves.

Leavesandstemsweredriedinanovenat55◦Ctoaconstantweight

andthenweighed.

Priortoplantharvest,theuppermostthreetoﬁvefullyexpanded

leavesofplantsfromalltreatmentsintheﬁrstfourblockswere

removedanddriedinadryingovenat55◦Ctoaconstantweight

then weighed. Dried leaves wereground witha Wiley millto

pass through a 0.84mm mesh screen and stored in glass jars

forlateranalysis.LeafelementalconcentrationsofNwere

deter-minedwithaLecoNanalyzer(TruSpecN,St.Joseph,MI).Samples

weredry ashed in a mufﬂefurnace at 500◦C, dissolvedin 20%

HCl, ﬁltered throughWhatman 41 ﬁlterpaper, and broughtto

theappropriatedilutionwith2%lanthanumsolution.Phosphorus

wasdeterminedcolorimetrically(Genesys10Spectrophotometer,

ThermoSpectronic,Rochester,NY)andK,Ca,Mg,Fe,Mn,andZn

wereanalyzedusingatomicabsorptionspectroscopy(PerkinElmer

model2380,Waltham,MA).

2.1.4. Experimentaldesignanddataanalysis

The experiment consisted of a randomized complete block

designwith10single-plantreplications.Becauseofﬁnancial

limi-tationsonlytheﬁrst4blockswereusedforfoliageNanalysis.Eight

treatments(twofertilizersappliedatfourrateseach)wereapplied.

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SASInstitute,Cary,NC),andapplicationratetrendswerecalculated

usingorthogonalcontrastswithineachfertilizertype.

2.2. Experiment2,elementalcombinations

2.2.1. Culturalpractices

‘MountainFreshPlus’tomatoseedlings weretransplantedas

describedaboveon25April.,2012.Thesiteandirrigationsystem

werethesameasthoseusedinexperiment1describedabove.

Cul-turalpracticeswereperformedasdescribedabove.Averagedaily

maximum/minimumairtemperatureswere32.3/19.1◦C.

2.2.2. Treatments

Thefollowingfertilizer treatmentswereapplied: (1)MAPat

4.9gm−2N,(2) calcium sulfate (CaSO4,23% Ca)at 9.8gm−2Ca,

(3)magnesiumoxide(MgO,58%Mg,CropMag58;Martin

Mari-etta, Baltimore, MD) at 11.0gm−2 Mg, (4) ammonium sulfate

((NH4)2SO4)Sulf-N;Honeywell,Morristown,NJ)at4.9gm−2N,(5),

TSP(Bonide, Oriskany,NY);0N-19.4P-0K(0N-45P2O5-0K2O,)at

7.1gm−2P,(6)handmixofCasulfate,Mgoxide,ammonium

sul-fate,andTSPattherateslistedintreatments2through5above,and

(7)nofertilizertreatment(control).AllN,P,Ca,andMgtreatments

wereappliedatratesequaltothatappliedwithMAP.Fertilizers

wereplacedinthebottomoftheplantingholeasdescribedabove

forplantsinrespectivefertilizertreatments.

2.2.3. Datacollection

Fruitwereharvestedbetween21June,2012and24July,2012

asredcolorappeared.Gradingwasasdescribedabovewithfruit

countedandweighed.

Plantswereharvested24July,2012andseparatedintomature

fruit,immaturefruit,leaves,stems,androots.Matureand

imma-ture fruit were air dried in a greenhouse with a daily high

temperatureofabout50◦C untildryand thenweighed.Leaves,

stems,androotsweredriedinovensat55◦Ctoaconstantweight

andweightsrecorded.

Nitrogen,P,K,Ca,Mg,Fe,Mn,andZnconcentrationwere

deter-minedasdescribedabove.WeightofN,P,K,Ca,Mg,Fe,Mn,orZn

foreachcomponentoftheplantwasdeterminedbymultiplying

thecomponentweightbytherespectivenutrientconcentration.

2.2.4. Experimentaldesignanddataanalysis

Treatments were arranged in a randomized complete block

designwithseventreatments(describedabove)and ten

single-plantreplications.Datawereanalyzedusingamixedmodel(PROC

MIXEDin SAS 9.4 software; SAS Institute, Cary,NC). Weighted

meanswerecalculatedusingLSMEANS withmeancomparisons

usingtheprotectedLSD(DIFFoption).

2.3. Experiment3,fertilizersolubilitykinetics

Thekineticsof nutrientrelease fromeach fertilizer material

listedabovefortreatments1–6(Section2.2.2),plusCRF,was

mon-itoredunderlaboratoryconditions.Fertilizerswereweighedand

placed in250mLbottles witha pH6 buffersolution(0.1MNa

acetate)toachieve asolid:solutionratioof1:2500.A pH6was

chosensincethiswasrepresentativeofthepHofthesoilusedin

theﬁeldexperiments.Foreachoftheseventreatments,six

sam-plesrepresentednutrientconcentrationsmeasuredat0.5,1,3,6,

24,and48hafterinitiationoftheexperiment.Eachtreatment-time

wasreplicatedthreetimes.Bottleswereplacedonareciprocating

shakerandremovedattheappropriatetimesforanalysis.Solutions

wereallowedtosettleforﬁveminutesbeforedecanting,andthen

analyzedforP,Ca,andMgbyatomicemissionspectroscopy,and

NH4-NandNO3-Nbyﬂowinjectionautoanalyzer(LACHAT,1994).

Solubility wasquantiﬁed and normalized by expressing the

massofthenutrientdissolvedpermassofnutrientcontainedin

thematerial.Thus,avalueofoneindicates100%solubilitywith

respecttoagivennutrient.

3. Results

3.1. Experiment1,magnesiumammoniumphosphateversus

controlledreleasefertilizer

Plantheightandwidth2weeksafterplantingandplantwidth

4 weeks after planting were greater for plants fertilized with

MAP(12.4cm,20.0cm,and34.4cm,respectively)thanforthose

fertilizedwithCRF (11.5cm, 18.5cm, and32.2cm, respectively)

(Table 1). Plants receiving fertilizer, regardless of source were

taller(26.2cm)andwider (34.5cm)4 weeksafterplantingand

wider(68.0cm)8weeksafterplantingthancontrolplants(22.5cm,

29.8cm,and61.0cm,respectively).Plantheightandwidthofplants

receivingMAPincreasedlinearlyasrateincreasedat2,4,and8

weeksafterplanting.Plantheightandwidthat4weeksafter

plant-ingandplantwidth8weeksaftertransplantingincreasedlinearly

as CRF rateincreased.Above-ground plantbiomass (stems and

leaves)wasgreaterwithfertilizerthanwithout,butdidnotdiffer

betweenthefertilizers.Above-groundbiomassincreasedlinearly

withMAPrate,butnorelationshipexistedbetweenabove-ground

biomassandCRFrate.

Thenumber,weightandperfruitweightofediblefruitdidnot

differamongfertilizersorbetweenuntreatedcontrolplantsand

thosereceivingfertilizer(Table2).Incontrast,totalweightand

perfruitweightofcullswasgreaterwithMAP(278.2gand22.7g,

respectively)thanwithCRF(193.9gand19.4g,respectively).The

numberofcullsandtotalweightofcullswasgreaterwitheither

fertilizer(8culls and284g,respectively)thanfornon-fertilized

controlplants(3cullsand93g,respectively).Thenumberofedible

fruit,numberofculls,andtotalweightofcullsincreasedlinearly

withincreasedMAPrate.Numberofcullsincreasedlinearlywhile

totalcullweightincreasedcurvilinearlyasCRFrateincreased.

FoliarNconcentrationdidnotdifferbetweenthetwofertilizer

treatments orbetweenplants receivingfertilizerand untreated

controlplants(Table3).AcurvilinearrelationshipbetweenMAP

concentrationandfoliarNconcentrationoccurredsuchthatplants

receiving2.45or4.9gm−2Nhadlowerfoliarconcentrationsthan

plantsreceivingnoMAPorMAPat9.8gm−2N.

Phosphorus concentrationin leavesdidnotdiffer regardless

offertilizertreatment,andPconcentrationinleavesfromplants

receivingeitherfertilizerdidnotdifferfromthatofnonfertilized

controlplants (Table3).Acurvilinear relationshipbetweenleaf

PconcentrationandMAPapplicationrateindicatedfertilization

with9.8gm−2NderivedfromMAPresultedinthehighestleafP

concentration.ThusitappearsthatMAPaddedmorePthanCRF

resultinginasigniﬁcanttrendbetweenapplicationrateandplant

Pconcentration.ControlledreleasefertilizerdidnotaffectleafP

concentration.

Plantsreceivingfertilizer(regardlessofsource)hadagreater

leafKconcentrationthannonfertilizedplants(Table3).Notrends

betweenKconcentrationandfertilizerapplicationrateoccurred

foreitherfertilizer.Notethatbothfertilizerscontainedonlytrace

amountsofK.LeafCaandMg concentrationswerenotaffected

bypresenceorabsenceoffertilizerorbyfertilizertype(datanot

shown).

NodifferencesinfoliarFe,Mn,orZnconcentrationoccurred

betweenplantsfertilizedwithMAPorCRForbetweenthe

non-fertilizedandfertilizedplants(datanotpresented).Likewise,no

trendsinfoliarFeorMnconcentrationoccurredwhenplantswere

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Table1

Tomatoplantheightandwidth(averageoftwoperpendicularmeasurements)2,4,and8weeksafterplanting(WAP)andabove-groundplantbiomass(stemsandleaves)at

harvestwithselectedratesofmagnesiumammoniumphosphate(MAP)orcontrolledreleasefertilizer(CRF)in2011.n=10.

Fertilizer Concentration(g/m2₎ ₂_WAP ₄_WAP ₈_WAP _Above-ground_biomass_(g)

Height(cm) Width(cm) Height(cm) Width(cm) Height(cm) Width(cm)

None 0 11.4 19.4 22.5 29.8 65.4 61.0 1596 MAP 2.45 11.7 18.2 24.2 33.8 67.4 64.0 1730 4.90 12.3 19.9 25.8 35.6 68.0 68.5 1833 9.80 13.9 22.4 29.8 38.6 71.6 70.2 2182 CRF 2.45 11.3 17.5 24.5 30.8 66.0 69.1 2009 4.90 11.9 19.1 26.6 34.3 67.9 67.2 1835 9.80 11.4 18.0 26.3 34.1 70.6 69.3 1811 Contrasts: MAPvs.CRF * ** NS ** NS NS NS Controlvs.fertilizer NS NS *** *** NS ** * MAP Lineara _** _** _*** _*** _* _** _** CRF Linear NS NS ** ** NS * NS

NS_,*_,**_,***_Contrasts_not_signiﬁcant_(NS)_or_signiﬁcant_at_P_≤_0.05,_0.01,_or_0.001,_{respectively.}

a_Quadratic_and_Residual_trends_were_not_signiﬁcant_for_height_or_width_at_any_number_of_days_after_treatment_for_either_fertilizer_(P_≤_0.05)._Likewise_quadratic_and_residual

trendswerenotsigniﬁcantforabove-groundbiomass.

Table2

Cumulativeedibleandcullfruitnumber,freshweight,andweightperfruitfromtomatoplantsfertilizedwithselectedratesofmagnesiumammoniumphosphate(MAP)or

controlledreleasefertilizer(CRF)in2011.n=10.

Fertilizer Rate(g/m2₎ _Edible_fruit _Culls

Fruit(no.) Totalwt.(g) Perfruitwt.(g) Fruit(no.) Totalwt.(g) Perfruitwt.(g)

None 0 18 887 50.8 3 93 22.2 MAP 2.45 19 904 51.0 8 334 29.7 4.90 16 996 69.1 7 278 18.3 9.80 25 1213 46.7 11 408 20.7 CRF 2.45 23 1053 48.2 7 220 14.4 4.90 22 1129 51.6 7 259 27.2 9.80 22 1030 41.8 7 203 13.6 Contrasts: MAPvs.CRF NS NS NS NS * * Controlvs.fertilizer NS NS NS *** *** NS MAP Linear * NS NS *** *** NS Quadratic NS NS * NS NS NS Residual NS NS NS * * NS CRF Linear NS NS NS * NS NS Quadratic NS NS NS NS * NS Residual NS NS NS NS NS NS

NS_,*_,**_,***_Contrasts_not_signiﬁcant_(NS)_or_signiﬁcant_at_P_≤_0.05,_0.01,_or_0.001,_{respectively.}

Table3

Nitrogen(N),phosphorus(P)andpotassium(K)percentageinleavesoftomatoplantsfertilizedwithselectedratesofmagnesiumammoniumphosphate(MAP),controlled releasefertilizer(CRF),ornofertilizer(control)in2011.n=4.Orthogonalcontrastsindicateifthereweresigniﬁcantdifferencesbetweenfertilizertreatmentsorsigniﬁcant trends(linearorquadratic)betweenappliedNrateandleafN,P,orKconcentrationwithineachfertilizer.

Fertilizer Rate(g/m2₎ _Leaf_N_concn_(%) _Leaf_P_concn_(%) _Leaf_K_concn_(%)

None 0 3.94 0.186 3.37 MAP 2.45 3.69 0.168 3.06 4.90 3.69 0.162 3.24 9.80 4.02 0.201 3.44 CRF 2.45 3.98 0.215 3.52 4.90 3.88 0.180 3.46 9.80 3.98 0.184 3.47 Contrasts: Controlvs.fertilizer NS NS * MAPvs.CRF NS NS NS MAP Linear NS NS NS Quadratic ** * NS Residual NS NS NS CRF Linear NS NS NS Quadratic NS NS NS Residual NS * NS

(6)

Table4

Foliarzinc(Zn)concentrationsfromtomatoplantsfertilizedwithselectedratesof magnesiumammoniumphosphate(MAP)oracontrolledreleasefertilizer(CRF). n=4.

Fertilizer Rate(g/m2₎ _Zn_concn(␮g/g_DW)

None 0 34.8 MAP 2.45 28.2 4.90 30.5 9.80 31.8 CRF 2.45 39.2 4.90 34.2 9.80 28.2 Contrasts: MAPvs.CRF NS Controlvs.fertilizer NS MAP Lineara _NS CRF Linear *

NS,*_Contrasts_not_signiﬁcant_or_signiﬁcant_at_P_≤_0.05,_{respectively.}

a_Quadratic_and_Residual_trends_were_not_signiﬁcant_for_Zn_{concentrations}_with

eitherfertilizer(P≤0.05).

Table5

Stemdryweightoftomatoplantsreceivingselectedfertilizertreatmentsin2012.

n=10.

Fertilizeradded Stemdryweight(g)

None 141abz

MAPy _171b

Handmixy _136ab

Ammoniumsulfate 116a

Triplesuperphosphatey _120a

Calciumsulfate 119a

Magnesiumoxide 110a

z _Means_followed_by_the_same_letter_are_not_{signiﬁcantly}_different_by_the_protected

LSD,P≤0.05.

y_MAP₌_magnesium_ammonium _phosphate;_hand_mix_refers _to_a_mixture_of

ammoniumsulfate((NH4)2SO4),triplesuperphosphate,calciumsulfate(CaSO4),

andMgoxide(MgO)atthesameconcentrationaseachofthesefertilizersapplied

inindividualfertilizertreatments.

concentrationwasnegativelyrelatedtoCRFratebutnotrendwas

apparentwithMAP(Table4).

3.2. Experiment2,elementalcombinations

StemdryweightofplantsreceivingMAPwasgreaterthanthat

ofplantsfertilizedwithammoniumsulfate,TSP,Casulfate,orMg

oxide(Table5).Root,leaf,andtotaldryweightdidnotdifferamong

fertilizertreatments(datanotpresented).

ThetotalfreshweightofediblefruitwasgreaterwithMAPor

thehandmixtureoffertilizerthanwithnofertilizerorwith

ammo-niumsulfate,Casulfate,orMgoxide(Table6).Theweightofgreen

fruitharvestedwasgreaterwithCasulfatethanwithMAP,butthe

weightofgreenfruitfromplantsinotherfertilizertreatmentsor

thecontroltreatmentdidnotdifferfromeithertheMAPtreatment

ortheCasulfatetreatment.Likewise,thenumberofgreenfruitper

plantwasgreaterwithCasulfatethanwithMAP,butother

treat-mentsdidnotdifferinnumberofgreenfruitperplantfromthose

treatedwithCasulfateorMAP.Cullandtotalfruitfreshweight

andediblefruit,cullandtotalfruitnumberperplantdidnotdiffer

amongtreatments(datanotpresented.

Theweightofediblefruitharvesteddidnotdifferamongthe

nonfertilized,MAP,andhandmixtreatmentsduringtheﬁrstthree

4-dayharvestintervals(Fig.1).Duringharvestinterval4through6,

plantsreceivingMAPorthehandmixtureyieldedagreaterweight

ofediblefruitthanplantsthatreceivednofertilizer.Neartheendof

thegrowingseason(harvestintervals7and8),presenceorabsence

offertilizerdidnotaffectediblefruityield.Thelackofresponseto

fertilizertreatmentattheendofthegrowingseasonmayberelated

Table6

Cumulativefreshweightandnumberofedibleorgreenfruitfromtomatoplants

receivingselectedfertilizertreatmentsin2012.n=10.

Fertilizeradded Ediblefruit Greenfruit Freshfruitweight/plant(g)

None 3861az _2996bc

MAPy _5478b _1961a

Handmixy _5770b _2636abc

Ammoniumsulfate 4263a 2834abc

Triplesuperphosphate 4838ab 2107ab

Calciumsulfate 4030a 3368c

Magnesiumoxide 3534a 2523abc

Fruitnumber/plant

None 19 25ab

MAPy ₂₈ _19a

Handmixy ₃₀ _25ab

Ammoniumsulfate 21 26ab

Triplesuperphosphate 24 23ab

Calciumsulfate 20 33b

Magnesiumoxide 19 25ab

z _Means_within_columns_and_fruit_weight_or_fruit_number_followed_by_the_same

letterarenotsigniﬁcantlydifferentbytheprotectedLSD,P≤0.05.

y_MAP₌_magnesium_ammonium_phosphate;_hand_mix_refers_to_a_mixture_of

andmagnesiumoxide(MgO)atthesameconcentrationaseachofthesefertilizers

appliedinindividualfertilizertreatments.

toexcessivetemperaturesreducingfruitsetinalltreatments.Sato

etal.(2000)showedthatthereleaseofpollengrainsandpollen

graingerminationisdecreasedinelevatedtemperaturesresulting

inlowerfruitset.Greaterﬂowerabortionalsoresultsinlowerfruit

setunderelevatedtemperatures(Satoetal.,2004).

Nitrogen concentrationdid notdiffer among fertilizer

treat-ments for anyplant parttested (datanot presented). Nitrogen

contentdidnotdifferamongfertilizertreatmentsforroots,stems,

orleaves,butredandgreenfruitNcontentdifferedamong

treat-ments.Plantsreceivingthehandmix offertilizerhadgreaterN

contentinredfruitthanredfruitreceivingnofertilizer,

ammo-niumsulfate,orMgoxide(Table7).Nitrogencontentofredfruitin

MAP,TSPorCasulfatetreatmentsdidnotdifferfromthatoffruit

fromplantsreceivingthehandmixtureorplantsreceivingno

fer-tilizer,ammoniumsulfate,orMgoxide.Nitrogencontentofgreen

fruitatterminationofthestudywasgreaterwithnofertilizerorCa

sulfatethanwithMAPorTSP.GreenfruitNconcentrationinplants

treatedwiththehandmix,ammoniumsulfate,orMgoxidedidnot

differfromthoseofplantsreceivingnofertilizerorCasulfateor

fromplantsreceivingMAPorTSP.

PhosphorusandKconcentrationdidnotdifferamongfertilizer

typeforanyofthetissuestested(datanotpresented).Phosphorus

andKcontentweregreatestingreenfruitfromnonfertilizedplants

orthosereceivingCasulfatewhilegreenfruitfromplantsfertilized

withMAPorTSPhadthelowestPandKconcentrations(Table7).

PhosphorusandKconcentrationingreenfruitfromplants

receiv-ingthehandmixture,ammoniumsulfate,orMgoxidedidnotdiffer

fromthatofanyotherfertilizertreatment.PhosphorusandK

con-tentdidnotdifferamongfertilizertreatmentsforanyotherplant

part.

Calciumconcentrationdidnotdifferamongfertilizertreatments

for anyplant part(datanot presented).Leaves of nonfertilized

plantsorthosereceivingMAPhadgreaterCacontentsthanthose

fertilizedwithammoniumsulfateorMgoxide(Table7).Leavesof

plantsfertilizedwiththehandmix,TSP,orCasulfatedidnot

dif-ferinCacontentfromleavesofplantsfertilizedwithanyother

fertilizer.RedfruitofplantsfertilizedwithMAPhadagreaterCa

contentthanredfruitfromanyotherfertilizertreatment(including

thenonfertilizedcontrol)exceptforthehandmix.Redfruitfrom

plantsfertilizedwiththehandmixdidnotdifferinCacontentfrom

(7)

nonfer-Fig.1.Tomatoharvestat4-dayintervalsfromplantsfertilizedwith4.9gm−2_magnesium_ammonium_phosphate_(MAP),_a_hand_mixture_of_calcium_sulfate,_magnesium

oxide,ammoniumsulfate,andtriplesuperphosphatetoprovidethesameamountofCa,Mg,N,andPastheMAP,ornotfertilized.Barswiththesameletterwithinharvest

intervalarenotsigniﬁcantlydifferentbytheprotectedLSD,P≤0.05.

Table7

Nitrogen(N),phosphorus(P),potassium(K)andcalcium(Ca)content(g/plantpart)

intomatoleaves,redfruit,andgreenfruitatharvestofplantsreceivingselected

fertilizertreatmentsin2012.n=10.

Fertilizerapplied Leaf Redfruit Greenfruit Total Ncontent(g/plantpart)

None 8.99 12.0az _4.12b _31.2

MAPy _8.68 _16.0ab _2.77a _34.0

Handmixy _7.30 _17.9b _3.51ab _32.4

Ammoniumsulfate 6.81 12.0a 3.71ab 26.6

Triplesuperphosphate 7.00 14.3ab 2.75a 27.7

Calciumsulfate 9.18 13.4ab 4.52b 32.9

Magnesiumoxide 6.46 11.4a 3.20ab 21.2

Pcontent(g/plantpart)

None 0.454 1.15 0.439b 2.52

MAPy _0.415 _1.37 _0.280a _2.52

Handmixy _0.330 _1.55 _0.361ab _2.48

Ammoniumsulfate 0.325 1.18 0.381ab 2.19

Triplesuperphosphate 0.362 1.35 0.289a 2.28

Calciumsulfate 0.461 1.23 0.476b 2.62

Magnesiumoxide 0.300 1.00 0.344ab 1.60

Kcontent(g/plantpart)

None 6.28 20.98 7.05b 43.27

MAPy _5.26 _27.07 _4.48a _46.59

Handmixy _4.37 _30.02 _5.89ab _45.49

Ammoniumsulfate 4.28 22.06 6.29ab 38.930

Triplesuperphosphate 4.79 25.85 4.84a 41.11

Calciumsulfate 5.99 23.48 7.70b 45.52

Magnesiumoxide 5.20 19.25 5.59ab 29.50

Cacontent(g/plantpart)

None 9.83b 0.457a 0.18b 13.52c

MAPy _10.16b _0.621b _0.10a _13.88c

Handmixy _7.90ab _0.603ab _0.13ab _10.85ac

Ammoniumsulfate 6.49a 0.502a 0.15ab 9.78ab

Triplesuperphosphate 7.28ab 0.520a 0.12a 9.89ab

Calciumsulfate 9.17ab 0.444a 0.19b 13.00bc

Magnesiumoxide 5.67a 0.427a 0.13ab 7.87a

z _Means_within_columns_and_N,_P,_K,_or_Ca_content_followed_by_the_same_letter_do

notsigniﬁcantlydifferbyLSD,P≤0.05.

y_MAP₌_magnesium_ammonium _phosphate,_hand_mix_refers_to_a_mixture_of

tilizedplants.Calciumcontentofgreenfruitfromplantsfertilized

withMAPorTSPwaslowerthanthatofgreenfruitfrom

nonfer-tilizedplantsorthosefertilizedwithCasulfate.Calciumcontent

ofgreenfruitfromplantsfertilizedwiththehandmix,ammonium

sulfate,orMgoxidedidnotdifferfromthatofgreen fruitfrom

anyotherfertilizertreatment.TotalplantCacontentwas

great-estinnonfertilizedplantsorthosefertilizedwithMAP,andlowest

inthosefertilizedwithMgoxide,TSPorammoniumsulfate.Total

plantCaofplantsreceivingCasulfatewasgreaterthantotalplant

CaofplantsreceivingMgoxide,butdidnotdifferfromthatof

non-fertilizedplantsorthosefertilizedwithMAP.Plantsfertilizedwith

thehandmixdidnotdifferinplantCacontentfromplantsinany

fertilizertreatmentornonfertilizedcontrolplants.

Magnesiumconcentrationandcontentdidnotdifferamong

fer-tilizertreatmentsforroots,stems,orleaves(datanotpresented).

Magnesiumconcentrationalsodidnotdifferamongfertilizer

treat-mentsforredfruit,butgreenfruitfromplantsfertilizedwithtriple

superphosphatehadagreaterMgconcentrationthangreenfruit

fromplantsfertilizedwiththehandmixorMg oxide(Table8).

GreenfruitofplantsfertilizedwithMAPorCasulfatedidnotdiffer

inMgconcentrationfromgreenfruitofplantsfertilizedwithany

otherfertilizerornonfertilizedplants.Magnesiumcontentinred

fruitfromplantsfertilizedwithMAPorthehandmixwasgreater

thanforredfruitfromplantsfertilizedwithMgoxide.Redfruit

fromnonfertilizedplantsorplantsfertilizedwithammonium

sul-fatehadalowerMgcontentthanredfruitfromplantsfertilized

withthehandmix.Redfruitfromplantsfertilizedwithtriple

super-phosphateorCasulfatedidnotdifferinMgcontentfromredfruit

ofnonfertilizedplantsorplantsfertilizedwithanyotherfertilizer.

Incontrast,greenfruitfromplantsfertilizedwithCasulfatehad

agreaterMgcontentthangreenfruitfromplantsfertilizedwith

MAPorTSP.Green fruitfromnonfertilizedcontrolplantshad a

greaterMgcontentthangreenfruitfromplantsfertilizedwithMAP.

Greenfruitfromplantsfertilizedwiththehandmix,ammonium

sulfate,orMgoxidedidnotdifferinMgcontentfromgreenfruitof

nonfertilizedplantsorplantsreceivinganyotherfertilizer.

IronandMnconcentrationsweresimilaramongfertilizer

treat-mentsforallplantpartstested(datanotpresented).Likewise,Fe

andMncontentofrootsandstemsandtotalplantFeandMn

con-tentdidnotdifferamongfertilizertreatments(datanotpresented).

(8)

Table8

Magnesium(Mg)concentration(%)andcontent(g/plantpart)inredandgreen

tomatofruitatharvestofplantsreceivingselectedfertilizertreatmentsin2012.

n=10forallotherplantparts.

Fertilizerapplied Plantpart

Redfruit Greenfruit Mgconcn(%DW)

None 0.167 0.242bcz

MAPy _0.158 _0.238abc

Handmixy _0.165 _0.232ab

Ammoniumsulfate 0.153 0.229a

Triplesuperphosphate 0.166 0.251c

Calciumsulfate 0.182 0.238abc

Magnesiumoxide 0.153 0.235ab

Mgcontent(g/plantpart)

None 0.750ab 0.312bc

MAPy _1.003bc _0.204a

Handmixy _1.105c _0.261abc

Ammoniumsulfate 0.745ab 0.276abc

Triplesuperphosphate 0.913abc 0.225ab

Calciumsulfate 0.876abc 0.341c

Magnesiumoxide 0.664a 0.252abc

z _Means_within_columns_and_Mg_{concentration}_or_content_followed_by_the_same

letterdidnotsigniﬁcantlydifferbyLSD,P≤0.05.Meanswithincolumnsand

ele-mentalconcentrationorcontentwithoutlettersdidnotsigniﬁcantlydiffer(P≤0.05)

amongtreatments.

y_MAP₌_magnesium_ammonium _phosphate,_hand_mix_refers_to_a _mixture_of

treatments,butFecontentofgreenfruitfromplantsfertilizedwith

ammoniumsulfate,Casulfate,ornonfertilizedcontrolplantswas

greaterthanwhenfertilizedwiththehandmixorTSP(Table9).

GreenfruitfromplantsfertilizedwithCasulfatehadagreaterFe

contentthanwhenfertilizedwithMgoxide,TSP,orthehandmix.

Leaf Mn contentwas greaterin nonfertilized plants than in

plantsfertilizedwithammoniumsulfate(Table9).Manganese

con-tentofleavesfromnonfertilizedplants orplantsfertilizedwith

ammoniumsulfatedidnotdifferfromthatofleavesfromplants

receivinganyotherfertilizertreatment.Manganesecontentofred

fruitfromplantsfertilizedwiththehandmixwasgreaterthanthat

ofredfruitfromplantsfertilizedwithMAP.Manganesecontentof

redfruitfertilizedwithMAPwasgreaterthanforredfruitfrom

plantsfertilizedwithMgoxideornonfertilizedplants.Redfruit

fromplantsfertilizedwithammoniumsulfate,TSP,orCasulfate

didnotdifferinMncontentfromredfruitofplantsfertilizedwith

MAP,Mgoxide,ornonfertilizedplants.Fertilizertreatmentsdid

notaffectMncontentofgreenfruit.

Zincconcentrationandcontentdidnotdifferamongfertilizer

treatmentsforrootsorstems,andtotalplantZncontentwassimilar

amongfertilizertreatments(datanotpresented).Zinc

concentra-tionwasgreaterinleavesofplantsfertilizedwithCasulfateorMg

oxidethaninfoliagefromplantsfertilizedwithammoniumsulfate,

thehandmix,ornonfertilizedplants(Table9).FoliarZn

concen-trationofplantsfertilizedwithMAPorTSPwasgreaterthanfoliar

Znconcentrationofplantstreatedwithammoniumsulfate,butdid

notdifferfromplantsreceivinganyotherfertilizerornonfertilized

plants.Zincconcentrationofgreenfruitfromplantsfertilizedwith

MAPwasgreaterthanZnconcentrationofgreenfruitfromplants

fertilizedwiththehandmix,Casulfate,orMgoxide,butgreenfruit

fromplantsfertilizedwithammoniumsulfate,TSP,ornonfertilized

plantsdidnotdifferinZnconcentrationfromgreenfruitofplants

fertilizedwithMAP,thehandmix,Casulfate,orMgsulfate.

Foliar Zncontent from plants fertilizedwith Casulfate was

greaterthanforplantsfertilizedwiththehandmix,ammonium

sulfate,orTSP.Zinccontentofredfruitfromplantsfertilizedwith

thehandmixwasgreaterthanforredfruitfromanyotherfertilizer

Table9

Iron(Fe)andmanganese(Mn)contentandzinc(Zn)concentrationandcontent

inleaves,redfruitandgreenfruitoftomatoplantsreceivingselectedfertilizer

treatmentsin2012.n=10forallplantparts.

Fertilizerapplied Plantpart

Leaf Redfruit Greenfruit Ironcontent(mg/plantpart)

None 22.9 21.5 11.2cdz

MAPy _23.0 _27.0 _10.3bcd

Handmixy _18.6 _32.1 _7.4ab

Ammoniumsulfate 16.3 27.1 11.4cd

Triplesuperphosphate 17.1 26.7 5.7a

Calciumsulfate 22.1 25.3 12.8d

Magnesiumoxide 14.9 22.3 7.9abc

Manganesecontent(mg/plantpart)

None 30.2b 7.7a 3.1

MAPy _26.6ab _10.5b _2.2

Handmixy _20.3ab _12.7c _2.8

Ammoniumsulfate 17.4a 8.1ab 2.9

Triplesuperphosphate 18.6ab 9.3ab 2.2

Calciumsulfate 25.0ab 9.4ab 3.5

Magnesiumoxide 19.9ab 6.9a 2.8

Zincconcn.(␮g/gDW)

None 29ab 25 64ab

MAPy _34bc ₂₂ _103b

Handmixy _31ab ₂₉ _49a

Ammoniumsulfate 27a 26 66ab

Triplesuperphosphate 35bc 27 60ab

Calciumsulfate 39c 28 56a

Magnesiumoxide 38c 26 32a

Zinccontent(mg/plantpart)

None 8.7abc 11.2a 8.3c

MAPy _9.8bc _13.9a _9.8c

Handmixy _7.2ab _19.4b _5.5ab

Ammoniumsulfate 6.0a 12.6a 7.9bc

Triplesuperphosphate 7.8ab 15.1a 5.4ab

Calciumsulfate 11.1c 13.1a 8.1bc

Magnesiumoxide 7.9abc 11.0a 3.4a

z _Means_within_columns_and_Fe_or_Mn_content_or_Zn_{concentration}_or_content

followedbythesameletterdonotsigniﬁcantlydifferbyLSD,5%level.Meanswithin

columnsandFeorMncontentwithoutlettersdidnotsigniﬁcantlydiffer(5%level)

amongtreatments.

y_MAP₌_magnesium_ammonium_phosphate,_hand_mix_refers_to _a_mixture_of

treatment(Table9).Zinccontentofgreenfruitfromnonfertilized

plantsorthosefertilizedwithMAPwasgreaterthanZncontent

ofgreenfruitfromplantsfertilizedwiththehandmix,TSP,orMg

oxide.

3.3. Experiment3,fertilizersolubilitykinetics

Basedonthesolubilityindexexperiment,nutrientreleasewas

alwaysfasterforconventionalsourcessuchasCasulfate,

ammo-niumsulfate,andTSP,comparedtoMAPandCRF(Fig.2).Infact,the

conventionalfertilizersreachednear100%solubilityveryquickly

forNandCa.Althoughthereleasewasslower,MAPwasgenerally

abletoachievenearlyequalnutrientreleasetoconventional

nutri-entsourcesbyhour48ofthesolubilityexperiment.Anexception

tothisgeneralobservationwasforMg;MAPreleasedmoreMgin

ashortertimecomparedtoMgoxide.Ingeneral,MAPwasmuch

moresolubleandhadfasterdissolutionkineticsthanCRP.

4. Discussion

Intheﬁrstexperiment,plantsreceivingtheslowlysoluble

fer-tilizerMAPweretallerandwiderthanthosereceivingCRFearly

(9)

Fig.2. Relativesolubility(nutrientmassreleased/totalnutrientcontent,avalueof0indicatescompleteinsolubilityand1completesolubility)ofnitrogen,controlled

releasefertilizer(CRF.circle)Y=0.0144logX-0.0004,R2₌_0.84,_p₌_0.01;_hand_mix_(square),_Y₌_0.0126logX₊_0.9612,_R2₌_0.39,_p₌_not_{signiﬁcant;}_triple_{superphosphate}_(TSP,

triangle),Y=0.1933logX+0.091,R2₌_0.87,_p₌_0.01;_ammonium_sulfate_is_not_shown,_all_relative_solubility_values_were_1._Phosphorus,_CRF_(circle)_Y₌_{0.009logX-0.0006,}

R2₌_0.81,_p₌_0.01;_hand_mix_(triangle)_Y₌_0.11logX₊_0.32,_R2₌_0.98,_p₌_0.001,_magnesium_ammonium_phosphate_(MAP,_square)_Y₌_0.17logX₊_0.10,_R2₌_0.86,_p₌_0.01,_TSP

(X)Y=0.12logX+0.37,R2₌_0.95,_p₌_0.001._Calcium,_hand_mix_(triangle)_Y₌_0.11logX₊_0.62,_R2₌_0.97,_p₌_0.001;_MAP_(square)_Y₌_0.11logX₊_0.006,_R2₌_0.77,_p₌_0.05,_TSP_(X)

Y=0.072logX+0.21,R2₌_0.88,_p₌_0.01;_calcium_sulfate_(circle)_Y₌_0.09logX₊_0.68,_R2₌_0.73,_p₌_0.05._Magnesium,_hand_mix_(triangle)_Y₌_{0.12logX-0.004,}_R2₌_0.81,_p₌_0.01;

MAP(square)Y=0.17logX+0.97,R2₌_0.87,_p₌_0.01;_magnesium_oxide_(circle)_Y₌_{0.027logX-0.0035,}_R2₌_0.75,_p₌_0.05.

wasprobablyquickerthantheCRFresultinginfasterplantgrowth.

Plantheightsbetweenfertilizedplantsweresimilarbyfourweeks

afterplantingandplantwidthsweresimilarbyeightweeks.The

positiverelationshipbetweenMAPconcentrationwithheightand

widthbutlackofaffectusingCRFaftertwoweeksgrowthsupports

thistheory.Byfourweeks,positivetrendsbetweenfertilizerwith

heightandwidthwereapparentforbothfertilizers(Table1).

NeitherslowlysolubleMAPnorCRFconsistentlyaffected

edi-blefruityieldduringtheﬁrstyear,butthenumberandweightof

cullswasgreaterwithbothfertilizersthanwithnofertilizer.This

differencemaybeexplainedbythelargernumberandweightof

fruitformedinthepresenceoffertilizercomparedtowithout

fer-tilizer.Cullswereprimarilyduetomechanicaldamagefrombirds

andotherwildlife.Thelargernumberoffruitorlargersizedfruit

infertilizedtreatmentsmayhavebeenmorevisiblyappealingand

readilyaccessibletowildlifethanintreatmentswithoutfertilizer.

AstudyofAmericanrobins(Turdismigratorius)showedthatberry

choicesmadeamong Crataegusmonogynafruitswerecorrelated

withfruitabundance, fruitsize,and fruitpulpiness(Sallabanks,

1993).Whilenottestedinthisstudy,itisalsopossiblethatfruit

fromfertilizedplantscontainedcompoundsthatmadethosefruit

moreattractivethanfruitfromnonfertilizedplants.Flemingetal.

(2008)foundthatinnectarivorousbirdlineageshexosewasthe

preferredsugar rather thansucrose in dilute diets,but sucrose

wasthepreferredsugar sourcein moreconcentrated diets.We

speculatethatthegreaterfruitabundance,highersolublesolids

orproteinconcentrationinfruitfromfertilizedplantsmayhave

contributedtogreaterdepredationlosses.

Inthesecondexperimentstemdryweightsofplantsandtotal

freshweightofedible fruitreceivingMAPorthehandmixture

ofindividualelementsgenerallywerelargerandproducedmore

fruitthanthoseplantsthatreceivedindividualnutrientsor

con-trolplants.Nonutrientdeﬁciencysymptomswerevisibleinany

treatment,includingthecontrols.Liebig’sLawof theMinimum

statesthatdeﬁciencyorabsenceofonenutrientwithallothers

presentlimitsplantgrowth(vanderPloegetal.,1999).Magnesium

ammoniumphosphateandthehandmixturehadseveral

nutri-entsmixedtogethertomeetplantdemands;whereas,ammonium

sulfate,Casulfate,orMgoxideprovidedonlyoneortwonutrient

elementsforplantuse.Fertilizationwithasingleelementappeared

toresultinbelowoptimalconcentrationsofcertainessential

ele-mentsonthose treatmentsthataffectedplantgrowthandfruit

development.Differencesinplantperformancedidnotconsistently

pointtoasingleelementbeinginadequate,butsuggestedthatfor

certainaspectsofplantdevelopmentdifferentelementswerein

shortsupply.PlantsreceivingCasulfatehadgreaternumbersand

weightsofgreenfruitatterminationoftheexperimentthanplants

receivingMAP(Table6).Calciumisimportantinfruitcellwalland

cellmembranestability,andCadeﬁcienciesoftenappearasfruit

malformationsincludingblossomendrotandcatfacingin

toma-toes(MayﬁeldandKelley,2012).Whilethesesymptomswerenot

presentinanytreatment,thehighlysolubleCasulfatemayhave

providedmoreCaforplantuptakeresultingingreatergreenfruit

numbersandweightsattheconclusionofthestudythanwiththe

slowlysolubleMAP.

Davidsonet al.(2000)notedthatnutrientintensityand

bal-ancearereﬂectedinthechemicalcompositionofplantpartswhen

plantsareinthesamestageofgrowthordevelopment,allother

factorsbeingconstant.In2011foliarNconcentrationinall

fertil-izertreatmentswaswithinthesufﬁciencyrangeof3.5%to5.1%for

broadleavedvegetableplants(BarkerandBryson,2007).However,

asigniﬁcanttrendofincreasingfoliarNconcentrationwithMAP

applicationrateexisted(Table3).Thefactthatthistrendoccurred

forMAPandnotCRFsuggeststhatNsuppliedfromCRFwasnot

assolubleasMAP.ThesolubilityindextestconﬁrmedthatMAP

releasedmoreNthanCRF,andatafasterrate(Fig.2).In2012,foliar

NconcentrationforuntreatedplantsandthosereceivingMAPwere

belowthesufﬁciencyrange,buttheydidnotdifferfromthoseof

plantsinothertreatmentsandwerenotlowenoughthatN

deﬁ-ciencysymptomswereapparent.Nitrogenconcentrationinboth

redandgreenfruitwassimilartofruitNconcentrationsreported

(10)

showednitrate-Ntobelacking,plantsabsorbedsimilaramountsof

Nregardlessoffertilizertreatments.Inthe1920sand1930s

cot-ton(GossypiumhirsutumL.)andwasacommoncropinthisregion,

anditwasoftengrownannuallyuntilsoilnutrientswere

inade-quatetoproduceaneconomicalreturn.Thisstudywasconducted

onsuchasite. Whencottonwasnolongerdeemedproductive,

theﬁeldwasabandonedandallowedtorevegetatenaturallyover

thenext60to80years.Whenitwastilledforthisstudy,the

pre-dominantvegetationwasnativeprairiegrassesandforbs.Organic

matterconcentrationsarerelativelyhighinsoilspopulatedwith

prairievegetation(Funderburg,1997)andwasabout2.3percent

inthis soil.Organicmatteris stableinuntilledsoiland usually

onlyabout5percentofitmineralizesyearly.Therateof

decom-positionisincreasedwithtillagewhentemperatureisfavorable

andtillageexposessoilorganicmattertooxygen,andirrigation

maintainsadequatemoisturetosupportrapidmineralizationby

microorganisms.WespeculatethatthissourceofN,notidentiﬁed

inthesoiltest,resultedinfewdifferencesintissueNconcentration

amongtreatments,despitelowsoilnitratepriortothestudy.

DifferencesinNcontentamongfertilizertreatmentsinredand

greenfruitwerenotduetodifferencesinNconcentrationamong

treatments,butratherduetodifferencesintheweightofredand

green fruit produced among the treatments. Elia and Conversa

(2012)notedthatexcessNresultsingreatervegetativegrowth

andlowerfruit set.In ourstudy,ammoniumnitratelikely

pro-videdNmorequicklythanMAP(Fig.2),butredfruitNcontent

didnotdifferbetweentheammoniumsulfate-treatedplantsand

MAP-treatedplants(Table7).TheinitialﬂushofsolubleNfrom

ammoniumsulfatemaynothavecorrespondedwiththetimingof

plantneedsforN,whileMAPservedasa slow-releaseNsource

(Fig.2).Incontrast,ammoniumsulfate waspresentinthehand

mix,andNcontentofredfruitwasgreaterwiththehandmixthan

withammoniumsulfatealone(Table7).Thissuggeststhatplantsin

theammoniumsulfatetreatmentlackedsomeotheressential

ele-mentthatresultedinlessfruitsetthanplantsreceivingthemixture

ofnutrientelementsinMAPorthehandmix.BecauseNcontent

ofredfruitfromthehandmix(containedN,P,S,Ca,andMg)was

greaterthanammoniumsulfate(containedNandS),andsincethe

handmixresultedinequalNcontentstoMAP(containedN,P,Ca,

andMg)andTSP(containedPandCa),itislikelythatincreasing

applicationofPaloneorincombinationwithCaimprovedoverall

Nuptake.

Inbothyears,Pconcentrationinallvegetativeplantparts

(rang-ingfrom0.109%to0.150%)regardlessoffertilizertreatmentwasat

thelowendofthesufﬁciencyrange(Sanchez,2007),andno

deﬁ-ciencysymptomsappearedsupportingthatPconcentrationwas

adequate.Phosphorus concentrationofred andgreen fruitwas

greaterthanforvegetativeplantpartsandwaswellwithinthe

sufﬁ-ciencyrange(Sanchez,2007)forplantsinallfertilizertreatments.

LeafK(3.36%),Ca(1.87%),andMg(0.51%)regardlessofpresence

orabsenceoffertilizerwerewithinestablishedsufﬁciencyranges

fortomato(Mengal, 2007;PilbeamandMorley,2007;Merhaut,

2007).TheunconventionalMAPreleasedPtothesamedegreeas

TSP,bothaloneandinamix,althoughthePreleasewassomewhat

delayedcomparedtoTSP.Comparedtotheun-conventionalCRF,

MAPreleasedmorePatafasterrate(Fig.2).

In2012,althoughP,K,andCaconcentrationdidnotdifferamong

fertilizertreatmentsinanyplanttissue,thetotalPandKcontentof

greenfruitandCacontentofleaves,redfruit,greenfruit,andtotal

Cacontentforplantsdifferedamongfertilizertreatments(Table7).

Thesevarianceswereattributedtodifferencesingrowthandfruit

yieldamong thefertilizer treatmentsin which biggerplants or

plantswithlargeryieldhadmorePandKingreenfruitandgreater

Cainleavesandfruit.Forexample,itisinterestingtonotethat

twoofthemostsolublePsources,asindicatedbythesolubility

experiment(MAPand TSP;Fig.2),containedsigniﬁcantlylessP

inthegreenfruitcomparedtothecontrolandCasulfate,which

receivednoP.ForCacontentsinleaves,redandgreenfruit,and

totalCa,noticethattheMAPandcontrolfertilitytreatmentswere

alwaysamongthetoptwo.Again,thissuggeststhattheabilityof

thefertilizertoreleasethenutrient(Fig.2)isnottheonlyfactor

thathasanimpactonCacontent.Itispossiblethatthetimingof

nutrientreleasecouldhaveaffectedthetotalCacontent;for

exam-ple,MAP,whichdidnotreleaseasmuchCaasCasulfate,provided

aslowreleaseofthenutrientthatmayhavecoincidedwithplant

uptakedemand.EventhoughCasulfate(eitheraloneorina

mix-ture)releasedmoreCathanMAP,theMAPtreatmentresultedin

greaterCacontentthanCasulfate,althoughnotalwayssigniﬁcant

(Table7).

Likewise,Mgconcentrationdidnotdifferforanytissuetested

exceptgreenfruit,buttheMgcontentofredfruitdifferedamong

fertilizertreatmentsduetomorefruitmassinsometreatments.

Magnesiumconcentrationofgreenfruitdifferedamongfertilizer

treatments,butitisinterestingtonotethatthegreatestMg

con-centration occurredwithTSP which contains noMg.Applied P

increasesrootgrowth(AnghinoniandBarber,1980;Borkertand

Barber,1985)andmayhavecontributedtoenhancedMguptake

andpartitioningtothegreenfruit.DespitethegreaterMg

concen-trationwithTSP,greenfruitfromplantsfertilizedwithCasulfate

containedmoreMgthanfruitfromplantsfertilizedwithTSP.Thus,

fruit yieldimprovedwithCa sulfate suchthat Mgcontent was

greaterinfruitfromthattreatmentdespitetheMgconcentration

advantageoffruitfromplantsfertilizedwithTSP.Theseresults

sug-gestthattheabilityofthefertilizertosupplyMghadlessimpact

ontheMgcontentofredandgreenfruitthandidthenutrient

bal-anceandaddedPsincethetopthreetreatmentsthatcontained

themostMginredfruitweretheonlyfertilizertreatmentsthat

addedP(Table8;mix,MAP,andTSP).Fromanotherperspective,

threeofthefourtreatmentswiththehighestMgcontentingreen

fruit(Table8;mix,MAP,andCasulfate)alladdedsulfate,which

increasesMgsolubility.Regardless,Fig.2showsthattheraw

abil-ityofthefertilizerstosupplyMgtosolutionwasthelargestand

mostefﬁcient(withregardtotime)forMAPcomparedtotheother

fertilizerthatcontainedMg,eitheraloneorinamix(e.g.Mgoxide).

FoliarFe,Mn,and Znconcentrationswerewithinsufﬁciency

rangesfor ﬁeld typetomato plants inalltreatments (Mills and

Jones, 1996).Ironand Mnconcentrations inthevarioustissues

testeddidnotdifferbyfertilizertreatment,buttotalFeandMn

contentinsometissuesdifferedbyfertilizertreatment.These

dif-ferenceswereassociatedwithtreatmentsaffectingdryweightof

thevariousplantparts.Thus,uptakeofFeandMnwasgreaterwhen

plantswerelargeralthoughconcentrationsofthesetwoelements

suggestednotreatmentdifferences.Incontrast,Znconcentration

differedinleavesandgreenfruitamongthefertilizertreatments.

AlthoughZnwasnotaddedasafertilizerothernutrientshada

small, but noticeable impacton leafZn concentration.BothCa

sulfateandMgoxidetreatmentsenhancedleafZnconcentration

compared tothecontrol,butotherplantparts wereunaffected

(Table9).TheZncontentofleavesandgreenfruitdidnotfollowthe

samepatternasZnconcentrationsinthesetissues,thustissue

con-centrationdoesnotaccountforallofthedifferencesinZncontent.

TheothervariableaffectingZncontentisdryweightofthevarious

plantpartsatharvest,whichimpactedZncontentofleaves,red

fruit,andgreenfruitmorethantheconcentration.

Fromthisstudy,weconcludethatthevariousfertilizerswere

effectiveinincreasingN,P,K,Ca,andMgand theymaintained,

increased,ordecreasedFe,Mn,andZninvariousplantparts.The

intensityoftheeffectsdiffereddependingonplantparttestedand

fertilizersource.Fertilizerdifferencesweremoreapparentintotal

nutrientcontentofvariousplantpartsthaninnutrient

concen-trationfor allofthenutrientsinvestigated.Thisreﬂectscertain

(11)

pro-ductionresultinginalargeamountofthenutrientabsorbedand

allocatedtoademandcenterthatwasnotdetectablebymeasuring

concentrationsbecauseofinherentvariability.Mixturesof

fertiliz-ers(MAP,CRF,andhandmix)didnotgreatlyaffectconcentration

ofN,P,K,Ca,orMgcomparedtotheindividualfertilizers.

Micronutrientcontentwasmoresensitivetofertilizertreatment

thanconcentrationforFeandMn.Thisreﬂectscertainnutrientsor

combinationsofnutrientsenhancinggrowthorproduction

result-inginalargeamountofthenutrientabsorbedandallocatedtoa

demandcenterthatwasnotdetectablebymeasuring

concentra-tions.Likewise,althoughdifferencesinZnconcentrationexisted

inleavesand green fruit,thedifferences in totalZncontent of

leaves,redfruitandgreenfruitfollowedadifferentpattern.

Mix-turesoffertilizers(MAP,CRF,andhandmix)minimallyaffected

theconcentrationofFeandMncomparedtotheindividual

fertil-izers.Sincenoneofthefertilizerscontainedmicronutrients,unless

unknowinglycontaminated,theelementspresentinthefertilizers

affectedmicronutrientuptakeandallocationpatternsindirectly.

Theabsenceofanelementlimitedplantgrowthornutrientuptake

in somesituations, and in other casesenhanced growth

creat-ingmoredemandforanotherelement.Inthisstudy,nonutrients

wereclearlydeﬁcient,butplantsrespondedinsomeinstanceswith

improvedgrowthoryield.Thissuggeststhateitherelemental

suf-ﬁciencyrangesmayrequireminoradjustmentorthattheratioof

certainnutrientsinindextissuemaybeusefulinﬁnetuningfertility

programs.

Acknowledgements

Approvedfor publicationbytheDirector,Oklahoma

Agricul-turalExperimentStation.Fundingforthisprojectwasprovidedby

theKansasLivestockFoundation.WethankKansasEnvironmental

ManagementAssociates,LLCforprovidingTerraPhos,Floricotefor

providingcontrolledreleasefertilizer,MartinMariettaMagnesia

SpecialtiesforprovidingCropMag58,andHoneywellforproviding

Sulf-N.WeappreciatethehelpofWilliamColeinﬁeldmaintenance

andweedcontrol.

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