BIOPHYSICAL SOIL QUALITY OF TILLAGE SYSTEMS IN CONVENTIONAL AND ORGANIC FARMING Stephen J. Crittenden BIOPHYSICAL SOIL QUALITY OF TILLAGE SYSTEMS IN CONVENTIONAL AND ORGANIC FARMING Thesis by StephenJ. CRITTENDEN Thesiscommittee Thesissupervisors Prof.Dr.L.Brussaard ProfessorofSoilBiologyandBiologicalSoilQuality WageningenUniversity Dr.M.Pulleman Seniorresearcher,DepartmentofSoilQuality WageningenUniversity Dr.M.Heinen Alterra,WageningenUniversityandResearchCentre Othermembers: Prof.Dr.S.Schrader JohannHeinrichvonThünen-Institute, Braunschweig,Germany Prof.Dr.Ir.S.E.A.T.M.vanderZee WageningenUniversity Dr.Ir.W.B.Hoogmoed WageningenUniversity Dr.G.Pérès AgrocampusOuest,INRA,Rennes,France ThisresearchwasconductedundertheauspicesoftheC.T.deWitGraduateSchoolfor ProductionEcologyandResourceConservation. Front&Back: CoverphotosbyStephenCrittendenandcolleagues. iii BIOPHYSICAL SOIL QUALITY OF TILLAGE SYSTEMS IN CONVENTIONAL AND ORGANIC FARMING StephenJ. CRITTENDEN Thesis submittedinpartialfulfilmentoftherequirementsforthedegreeofdoctor atWageningenUniversity bytheauthorityoftheRectorMagnificus Prof.Dr.Ir.A.P.J.Mol, inthepresenceofthe ThesisCommitteeappointedbytheAcademicBoards tobedefendedinpublic onWednesdaythe9thofDecember2015 at08:30intheAula. iv StephenJ.Crittenden Biophysicalsoilqualityoftillagesystemsinconventionalandorganicfarming,138pages. Thesis,WageningenUniversity,Wageningen,NL(2015),withreferencesandsummaryin English ISBN0000-000 Andwhatdoesthewordqualitymean?Tomeitmeanstexture.Thisbookhaspores. Ithasfeatures.Thisbookcangounderthemicroscope.You’dfindlifeunderglass, streamingpastininfiniteprofusion.Themorepores,themore truthfullyrecordeddetailsoflifepersquareinchyoucangetonasheetofpaper, themore’literary’youare.That’smydefinition,anyway.Tellingdetail. Freshdetail.Thegoodwriterstouchlifeoften. -RayBradbury,Fahrenheit451 C ONTENTS 1 Introduction 1 1.1 Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.1 Non-inversiontillage. . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1.2 Organicfarming . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.3 Controlledtrafficfarming . . . . . . . . . . . . . . . . . . . . . . 3 1.1.4 Fieldmarginstrips. . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Soilphysicalquality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Earthworms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.4 Thesisobjectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.5 Thesisoutline. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2 Effectoftillageonearthwormsovershort-andmedium-terminconventional andorganicfarming 7 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2 Materialsandmethods . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2.1 Sitecharacteristics. . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2.2 Experimentaldesign. . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2.3 Datacollectionandanalyses. . . . . . . . . . . . . . . . . . . . . 12 2.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.3.1 Short-termstudy: effectofmouldboardploughingonearthworm populations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.3.2 Medium-term study: effect of reduced tillage systems on earth- wormpopulations . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.3.3 Relationsbetweenearthworms,management,andsoilproperties. . 20 2.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.4.1 Short-termeffectsofploughingonearthworms . . . . . . . . . . . 20 2.4.2 Medium-termeffectsofreducedtillageonearthworms . . . . . . . 22 2.4.3 Relationsbetweenearthwormsandsoilproperties . . . . . . . . . 24 2.5 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3 Earthwormassemblagesasaffectedbyfieldmarginstripsandtillageinten- sity:anon-farmapproach 27 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 3.2 Materialsandmethods . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.2.1 Studyarea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.2.2 Experimentaldesign. . . . . . . . . . . . . . . . . . . . . . . . . 31 3.2.3 Farmmanagement. . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.2.4 Samplingandlaboratoryanalyses . . . . . . . . . . . . . . . . . . 34 3.2.5 Statisticalanalyses. . . . . . . . . . . . . . . . . . . . . . . . . . 35 vii viii CONTENTS 3.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.3.1 Distancefromfieldmarginstrips . . . . . . . . . . . . . . . . . . 35 3.3.2 Tillagecomparison. . . . . . . . . . . . . . . . . . . . . . . . . . 36 3.3.3 Soilpropertiesandearthworms . . . . . . . . . . . . . . . . . . . 36 3.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 3.4.1 Earthwormsinfieldmarginstrips . . . . . . . . . . . . . . . . . . 42 3.4.2 Earthwormsasaffectedbytillagesystems . . . . . . . . . . . . . . 44 3.4.3 Earthworm,soilproperty,andmanagementrelations . . . . . . . . 45 3.5 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4 Soil physical quality in contrasting tillage systems in organic and conven- tionalfarming 47 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.2 Materialsandmethods . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.2.1 Sitedescription . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 4.2.2 Experimentaldesign. . . . . . . . . . . . . . . . . . . . . . . . . 51 4.2.3 Soilwaterretention . . . . . . . . . . . . . . . . . . . . . . . . . 52 4.2.4 Field-saturatedhydraulicconductivity. . . . . . . . . . . . . . . . 52 4.2.5 Soilwatercontent . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.2.6 Aggregatestability . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.2.7 Drybulkdensity . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.2.8 Penetrationresistance . . . . . . . . . . . . . . . . . . . . . . . . 54 4.2.9 Soilorganicmattercontentandcarbonstocks. . . . . . . . . . . . 54 4.2.10 Cropyield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.2.11 Statisticalanalysis . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.3.1 Effectoftillageonsoilwaterretention. . . . . . . . . . . . . . . . 55 4.3.2 Effectoftillageonfield-saturatedhydraulicconductivity . . . . . . 56 4.3.3 Effectoftillageonsoilwatercontent. . . . . . . . . . . . . . . . . 56 4.3.4 Effectoftillageonaggregatestability. . . . . . . . . . . . . . . . . 56 4.3.5 Effectoftillageonsoildrybulkdensity . . . . . . . . . . . . . . . 56 4.3.6 Effectoftillageonpenetrationresistance . . . . . . . . . . . . . . 56 4.3.7 Effectoftillageonsoilorganicmattercontentandcarbonstocks . . 57 4.3.8 Effectoftillageoncropyield. . . . . . . . . . . . . . . . . . . . . 57 4.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4.4.1 Soilphysicalfunctions. . . . . . . . . . . . . . . . . . . . . . . . 57 4.4.2 Soilstructuralparameters . . . . . . . . . . . . . . . . . . . . . . 61 4.4.3 Soilorganicmatterandcarbonstocks . . . . . . . . . . . . . . . . 62 4.4.4 Cropyield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.5 Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 5 Soilwaterandtemperaturedynamicsincontrastingtillagesystemsunder conventionalandorganicfarming 65 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 5.2 MaterialsandMethods . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 5.2.1 Sitedescription . . . . . . . . . . . . . . . . . . . . . . . . . . . 69