35Solibiodiversityeffectsfromfieldtofork

OpinionSoilBiodiversityEffectsfromFieldtoForkMatthiasC.Rillig,1,2,*,@AnikaLehmann,1,2JohannesLehmann,3TessaCamenzind,1,2andCorneliaRauh4Ourknowledgeofsoilbiodiversityinagricultureingeneraliscurrentlyincreas-ingrapidly.However,almostallstudieshavestoppedwiththequantificationofsoilbiodiversityeffectsoncropsatharvesttime,ignoringsubsequentpro-cessesalongtheagrifoodchainuntilfoodarrivesonourplates.Herewedevelopaconceptualframeworkforthestudyofsuchpostharvesteffects.Wepresentthemainmechanisms(directandindirect)viawhichsoilbiodiver-sitycaninfluencecropqualityaspectsandgiveexamplesofhoweffectsatharvesttimemaybecomeattenuatedthroughpostharvestoperationsandhowbiodiversitymayalsoaffectsomeoftheseoperations(i.e.,storage)themselves.Futureresearchwithabroaderfocushasthepotentialtounveilhowsoilbiodiversitymaybenefitfromwhatendsuponourforks.KnowledgeofSoilBiodiversityEffectsStopsontheFieldTheenormouschallengesrelatedtoachievingfoodsecurityforanexpected9billionpeoplehaveledtocloserscrutinyofagrifoodchains(seeGlossary)[1].Inadditiontoprimaryproductioninfields,thisencompassesaseriesof‘post-farmgate’processes,whichincludeprocessing,packaging,storing,distribution,resale,preparation,andconsumption.Alloftheseprocessesarecriticaltofoodsecurity(e.g.,[2]),togetherwiththeprevailingsocioeconomicconditions.Inparalleltherehasbeenagrowingappreciationoftheinterrelationshipbetweensoilbiodiversity(Box1)andagroecosystems.Thislineofresearchhasfocusedmostlyonpotentiallyadverseeffectsofagricultureonsoilbiota,theroleofsoilbiotaininfluencingyield,andthechallengeofsustainablymanagingsoilsandtheirbiotawhilesecuringfoodproduction[3–5].Researchiswellunderwaytoshedlightontheseproblems.Forexample,theliteratureisrichwithexamplesoftheeffectsofvarioussoilbiota,suchassymbioticarbuscularmycor-rhizal(AM)fungi,onvariousaspectsofcropyieldandaspectsofcropquality(e.g.,[6–8]).Suchdataontheeffectsofsoilbiotaoncropyieldandqualityarevaluableandhavebeeninstrumentalinformulatingcallstooptimizethemanagementofsoilbiodiversityforsustainableagricultureandyieldstability[3,9,10].Nevertheless,researchhasmostlystoppedshortoflookingathowinteractionsinthefielddeterminewhatendsuponourplates.Hereweintroducetheconceptthatripple-oneffectsofsoilbiodiversityshouldalsobeexaminedaftertheplant’sharvest,followingthechainofeventsthatleadstovariousfoodproducts.Weknowastonish-inglylittleaboutthis,andherewedevelopaframeworktoextendthescopeofhowweexaminesoilbiodiversityeffectsbeyondthecropharvest(Figure1,KeyFigure).Thisframeworkcomprises:(i)recognizingbothdirectandindirectmechanismsofsoilbiodiversityeffectsoncropproperties;(ii)identifyingpostharvestprocessesthataffectbiodiversitylegacyeffectsoncropproperties;and(iii)pinpointingbiodiversity-relatedcroppropertiesthatinfluencetheefficacyandsuccessofoperationsoccurringintheagrifoodchain(Figure2).TrendsOurgeneralunderstandingofsoilbio-diversityinagricultureiscurrentlyincreasingrapidly.Itisnowclearthatthereisanimportantroleforvarioussoilbiotanotonlyindrivingcropyieldbutalsointhequalityandpotentialhealthbenefitsoffoodasdeterminedatthetimeofharvest.Agrifoodchainsareunderscrutinyfortheircontributiontofoodsecurity.1FreieUniversitätBerlin,InstitutfürBiologie,D-14195Berlin,Germany2Berlin-BrandenburgInstituteofAdvancedBiodiversityResearch(BBIB),D-14195Berlin,Germany3CornellUniversity,CollegeofAgricultureandLifeSciences,Ithaca,NY14853,USA4TechnischeUniversitätBerlin,DepartmentofFoodBiotechnologyandFoodProcessEngineering,D-14195Berlin,Germany@Twitter:@mrillig*Correspondence:[e-mail](M.C.Rillig).URL:://doi.org/10.1016/j.tplants.2017.10.0031©2017ElsevierLtd.Allrightsreserved.TRPLSC1618No.ofPages8MechanismsofSoilBiodiversityEffectsWerecognizetwobroadmechanismsbywhichsoilbiotacanaffectpostharvestproperties:thepresenceofthemicrobesthemselvesinorontheharvestedpartoftheplantandtheindirecteffectsofsoilandroot-colonizingsoilbiotaonthechemicalpropertiesoftheharvestedplanttissues.Inmoststudies,individualsoilbiotagroupshavebeenexaminedinisolation;forexample,mycorrhizalfungiorplant-growth-promotingbacteria(PGPBs).Animportantcom-ponentofsoilbiodiversityisbiotainteractions(Box1)andheretheevidenceiscurrentlyrelativelythinforinteractiveeffectsthatmayaffectcropquality.Todateonlyafewexamplesareavailable(Table1),buttheseareneverthelessacrucialpieceofevidencepromptingstudiesthatexaminetheeffectsofvaryingoverallsoilbiodiversity.PresenceofMicrobesofSoilOriginontheHarvestedPlantPortionSoilmicrobiotacancolonizetheportionoftheplantthatisharvested;thatis,theyaredirectlypresentintheitemharvestedandcanthereforepotentiallycontinuetoaffectportionsoftheprocessfollowingaharvest.Thiscanhappenintwoways:(i)theharvestedplantportionisbelowgroundandthereforealreadydirectlyexposedtothesoilbiota,suchastubers;or(ii)thesoilbiotacanberecruitedfromthesoiltotheharvestedplantportion.Thiscanoccur,forexampleingrapes,whereZarraonaindiaetal.[11]haveshownthatthesoilmicrobiomeisareservoirforthebacter