NitrogenNitrogen FertilityFertility ManagementManagement inin OrganicOrganic ProductionProduction

RichardRichard Smith,Smith, FarmFarm AdvisorAdvisor Monterey,Monterey, SantaSanta CruzCruz andand SanSan BenitoBenito CountiesCounties CharacteristicsCharacteristics ofof thethe OrganicOrganic ProductionProduction SystemSystem

• Nearly all N is provided by organic sources • Mineralization needs to occur to produce and ammonium for plant growth • There is a need to build up levels of soil which is used as source of N for crop growth • Cover crops, crop residues and also contribute N for crop growth NitrogenNitrogen CycleCycle Crop residue, Compost, Soil Organic Matter Most soil N is in this form Fertilizers (1000 – 3000 lbs N/A)

Death Mineralization* Death

+ CEC NH4

Plants Nitrification Microbes

- NO3

* Mineralization is a key step in making N available for plant growth It is dependent upon adequate soil temperatures (i.e. > 50 F) SourcesSources ofof NitrogenNitrogen forfor CropCrop GrowthGrowth

1.1. ResidualResidual mineralmineral NN (NO(NO3 --NN andand NHNH4 --N)N) 2.2. InIn seasonseason mineralizationmineralization ofof NN fromfrom soilsoil organicorganic mattermatter 3.3. NN availabilityavailability fromfrom priorprior cropscrops && covercover cropscrops 4.4. OrganicOrganic FertilizerFertilizer 1.1. ResidualResidual SoilSoil MineralMineral NN (nitrate(nitrate andand ammoniumammonium pool)pool)

•• CanCan bebe measuredmeasured withwith thethe PresidedressPresidedress NitrateNitrate QuickQuick TestTest PresidedressPresidedress NitrateNitrate QuickQuick TestTest ResidualResidual SoilSoil MineralMineral NN

•• NitrateNitrate isis typicallytypically lowlow inin organicorganic productionproduction systemssystems • Organic systems differ from conventional systems in that N management cannot typically be based on measuring a large pool of N in the soil • This can vary however, depending upon fertilization practices ComparisonComparison ofof OrganicOrganic andand ConventionalConventional OnionsOnions Hollister,Hollister, 19961996 80

70

60 Conventional 50

40

30

Soil ppm NO3-N 20 Organic 10

0 May May Jun Jun Jul Jul Jul Aug SoilSoil NitrateNitrate inin OrganicOrganic VegetableVegetable ProductionProduction 20012001 -- 20032003 25

20 0-15 cm

dry soil soil dry 15 -1 15-30 cm

10 -N µg g µg -N 3 5 NO 0

r1 r1 r2 r3 3 r3 -Y ll-Yr2 r l-Yr r-Y g-Y a g-Y e al e Fall-Yr1 F rin F p int Winter-Yr1Sprin Winter-Yr2S W Summer-Y Summer-Yr2 Summ Jackson, 2005 2.2. InIn seasonseason mineralizationmineralization ofof NN fromfrom soilsoil organicorganic mattermatter •• 22 toto 55 %% ofof soilsoil organicorganic mattermatter decomposesdecomposes annuallyannually •• AsAs thethe organicorganic mattermatter decomposesdecomposes NH4NH4+ andand nitratenitrate NO3NO3- areare releasedreleased InIn seasonseason mineralizationmineralization ofof NN fromfrom soilsoil organicorganic mattermatter •• AA roughrough estimateestimate ofof mineralizationmineralization fromfrom soilsoil organicorganic mattermatter cancan bebe mademade basedbased onon thethe amountamount ofof organicorganic NN presentpresent inin thethe soilsoil andand thethe percentpercent ofof thatthat NN likelylikely toto mineralizemineralize overover aa givengiven periodperiod ofof time.time. InIn seasonseason mineralizationmineralization ofof NN fromfrom soilsoil organicorganic mattermatter ForFor aa soilsoil withwith 1%1% organicorganic matter:matter: •• 2,8002,800 lblb organicorganic NN // acreacre xx 0.020.02 (percent(percent ofof organicorganic NN thatthat mineralizesmineralizes inin 6060 days)days) ==

5656 lblb plantplant availableavailable NN // acreacre overover twotwo monthsmonths NitrogenNitrogen ReleaseRelease CharacteristicsCharacteristics ofof NN SoilSoil OrganicOrganic MatterMatter

20

15

10

5 Soil organic matter mineralization Available Nitrate (ppm) Nitrate Available

Relative Rate of N Mineralization 3.3. NN availabilityavailability fromfrom covercover cropscrops

•• CoverCover cropscrops typicallytypically taketake upup oror fixfix betweenbetween 100100-- 200200 lbslbs N/N/ acreacre •• CoverCover cropscrops areare oftenoften tilledtilled intointo thethe soilsoil whenwhen thethe C:NC:N ratioratio <20<20 toto achieveachieve aa netnet releaserelease ofof NN toto thethe soilsoil toto feedfeed subsequentsubsequent vegetablevegetable cropscrops •• CoverCover cropscrops withwith aa lowlow NN contentcontent suchsuch asas maturemature cerealscereals (i.e.(i.e. C:NC:N ratioratio >> 20)20) temporarilytemporarily tietie upup *nitrogen*

* soil microbes utilize available soil N to break down the cover crop residue NitrogenNitrogen releaserelease fromfrom covercover cropcrop residueresidue basedbased onon thethe NN contentcontent Percent N Examples of Cover Crops Nitrogen Release in Cover Crop

Will Tie up N 0.50.5 Cereal Straw Will Tie up N 1.01.0 Cereal Straw Will Tie up N 1.51.5 Cereal at heading May Tie up N* 2.02.0 Cereal pre heading May Tie up N* 2.52.5 Mustards at heading and Imm. cereal Will Release N 3.03.0 Mustards, legumes and juvenile cereal Will Release N 3.53.5 Legumes and immature mustards Will Release N 4.04.0 Legumes CoverCover CropCrop DependsDepends uponupon ProteinsProteins C:N;C:N; ligninlignin andand PolyphenolsPolyphenols

Microbes MicrobesMicrobes

AvailableAvailable TypicallyTypically <10<10--30%30% ofof covercover cropcrop NN isis takentaken upup byby thethe firstfirst subsequentsubsequent MineralMineral Crop*Crop* NitrogenNitrogen

* A good deal of cover crop N remains in the system and can can be taken up in later years (i.e. 73%) NN availabilityavailability fromfrom covercover cropscrops

•• TheThe raterate ofof mineralizationmineralization ofof availableavailable NN fromfrom aa lowlow C:NC:N (<20)(<20) covercover cropcrop increasesincreases overover aa threethree-- toto sixsix--weekweek periodperiod followingfollowing incorporationincorporation •• SoilSoil NN levelslevels returnreturn toto prepre--incorporationincorporation levelslevels byby weekweek 66--1010 NN ReleaseRelease PatternPattern fromfrom CoverCover CropsCrops

18 Legume Mix 16 Mustard Oats 14

12

10

8

6

4 Total Mineral Nitrogen (ppm) Nitrogen Mineral Total

2

0 0 1125395367 Days After Incorporation of Cover Crop Smith & Brennan, 2003 NitrogenNitrogen ReleaseRelease CharacteristicsCharacteristics ofof NN FromFrom CoverCover CropCrop

20

15 Cover Crop Incorporation Cover Crop Mineralization 10

5 Soil organic matter mineralization Available Nitrate (ppm) Nitrate Available

Relative Rate of N Mineralization 4.4. NN AvailabilityAvailability fromfrom OrganicOrganic FertilizersFertilizers MaterialMaterial NitrogenNitrogen MaterialMaterial NitrogenNitrogen Chilean nitrate 1616 Soybean meal 77 Blood meal 1212 Processed liquid 44 fish meal 1212 Alfalfa meal 44 and 99--1212 Pelleted 22--44 guano Fish meal or powder 1010--1111 Bone Meal 22 Meat and bone meal 88 Kelp <1<1 PelletedPelleted PoultryPoultry ManureManure NetNet NN MineralizationMineralization

40 35 30 25 20 59 15 77 10 5 0 1 Week 4 Weeks 8 Weeks IncubationIncubation -- WeeksWeeks Hartz and Johnstone, 2006 FishFish PowderPowder NetNet NN MineralizationMineralization

70 60

50 40 59 30 77 20 10 0 1 Week 4 Weeks 8 Weeks IncubationIncubation -- WeeksWeeks Hartz and Johnstone, 2006 FeatherFeather MealMeal NetNet NN MineralizationMineralization

70 60

50 40 59 30 77 20 10 0 1 Week 4 Weeks 8 Weeks IncubationIncubation -- WeeksWeeks Hartz and Johnstone, 2006 PercentPercent ofof InitialInitial OrganicOrganic NN MineralizedMineralized –– 44 WeeksWeeks IncubationIncubation

70 60 50 40 30 59 77 20 10 0 pelleted sea fish powder feather meal guano

Hartz and Johnstone, 2006 NitrogenNitrogen ReleaseRelease CharacteristicsCharacteristics ofof NN FromFrom FertilizerFertilizer

Fertilizer Mineralization 20

15

10

5 Soil organic matter mineralization Available Nitrate (ppm) Nitrate Available

Relative Rate of N Mineralization IntegratingIntegrating SourcesSources ofof NN forfor OrganicOrganic ProductionProduction 20062006 CoverCover CropCrop xx FertilizerFertilizer TrialTrial

•• TheThe covercover cropcrop plotsplots producedproduced 3.23.2 tonstons ofof biomassbiomass andand containedcontained 194.5194.5 lbslbs N/AN/A •• TheThe covercover cropcrop waswas incorporatedincorporated FebruaryFebruary 1414 1212 inchesinches ofof rainrain fellfell betweenbetween incorporationincorporation ofof thethe covercover cropcrop andand transplantingtransplanting broccolibroccoli onon AprilApril 2020 RainRain EventsEvents BetweenBetween CoverCover CropCrop IncorporationIncorporation andand TransplantingTransplanting BroccoliBroccoli

Rainfall Events 1.0 14 Cum. Rainfall 0.9 12

0.8 )

0.7 10

) 0.6 8 0.5

0.4 6 Rainfall (in. Rainfall 0.3 4

0.2 (in. Rainfall Cumulative 2 0.1

0.0 0 14-Feb 21-Feb 28-Feb 7-Mar 14-Mar 21-Mar 28-Mar 4-Apr 11-Apr 18-Apr SoilSoil TemperaturesTemperatures BetweenBetween CoverCover CropCrop IncorporationIncorporation andand TransplantingTransplanting BroccoliBroccoli

65

60

55

50

45

40

35 Soil Temperature (degrees F) Soil Temperature

30 14-Feb 21-Feb 28-Feb 7-Mar 14-Mar 21-Mar 28-Mar 4-Apr 11-Apr 18-Apr TotalTotal MineralMineral NitrogenNitrogen inin SoilSoil BetweenBetween CoverCover CropCrop IncorporationIncorporation andand TransplantingTransplanting BroccoliBroccoli

Total Mineral Nitrogen, Hartnell Organic Plot 2006

12.0 CC No CC )

10.0

8.0

6.0

4.0

2.0 Total Mineral N (mg/kg +/- SEM +/- (mg/kg N Mineral Total 0.0 21-Feb 1-Mar 9-Mar 16-Mar 23-Mar 31-Mar 6-Apr 13-Apr 20-Apr

HarvestHarvest –– NumberNumber ofof HeadsHeads Number/ANumber/A

50000 45000 No Cover Crop 40000 Cover Crop 35000 30000 25000 20000 15000 10000 5000 0 0 75 150 225 PoundsPounds N/AN/A HarvestHarvest –– WeightWeight ofof HeadsHeads Tons/ATons/A

8 7 No Cover Crop 6 Cover Crop 5 4 3 2 1 0 0 75 150 225 PoundsPounds N/AN/A NN availabilityavailability fromfrom covercover cropscrops

•• ItIt isis likelylikely thatthat aa substantialsubstantial portionportion ofof thethe nitrogennitrogen containedcontained inin thethe covercover cropcrop waswas lostlost toto leachingleaching priorprior toto plantingplanting thethe broccolibroccoli •• InIn spitespite ofof thesethese conditions,conditions, therethere waswas anan increaseincrease ofof 2525 lbslbs ofof N/AN/A inin thethe biomassbiomass ofof broccolibroccoli inin covercover croppedcropped plotsplots vsvs nonnon--covercover croppedcropped plotsplots atat thethe endend ofof thethe growinggrowing season.season. •• MarkMark GaskellGaskell hashas typicallytypically seenseen covercover cropscrops toto contributecontribute 100100 lbslbs ofof N/AN/A inin studiesstudies onon pepperspeppers andand cabbagecabbage HighHigh YieldingYielding TreatmentsTreatments LowLow SynchronySynchrony formform CoverCover CropCrop butbut GoodGood SynchronySynchrony ofof NN ReleaseRelease fromfrom FertilizerFertilizer

Crop Demand

Fertilizer 20 Mineralization 15 Cover Crop Incorporation Cover Crop Mineralization 10

5 Soil organic matter mineralization Available Nitrate (ppm) Nitrate Available

Relative Rate of N Mineralization LowLow YieldingYielding TreatmentsTreatments hadhad PoorPoor SynchronySynchrony betweenbetween NN AvailabilityAvailability fromfrom CoverCover CropCrop andand FertilizerFertilizer RatesRates thatthat werewere tootoo LowLow

Crop Demand

Fertilizer 20 Mineralization 15 Cover Crop Incorporation Cover Crop Mineralization 10

5 Soil organic matter mineralization Available Nitrate (ppm) Nitrate Available

Relative Rate of N Mineralization OrganicOrganic FertilizerFertilizer FormForm andand TimingTiming TrialTrial Watsonville,Watsonville, 20012001

Treatment Preplant Top Top Top Total May 8 dress dress dress May 31 June 7 June 14 Untreated 00 00 00 00 00 Fert Treat No. 1 4545 4545 4545 4545 180180 Fert Treat No. 2 9090 00 4545 4545 180180 Fert Treat No. 3 135135 00 00 4545 180180

1)1) MeatMeat MealMeal 88--55--1;1; 2)2) FeatherFeather MealMeal 1212--00--00 3)3) BloodBlood MealMeal 1313--00--0;0; 4)4) Guano/ChickenGuano/Chicken 77--00--00 NitrateNitrate--NitrogenNitrogen inin thethe SoilSoil ofof 135135--4545 FertilizerFertilizer TreatmentsTreatments OrganicOrganic Broccoli,Broccoli, Watsonville,Watsonville, 20012001 50

40 30 Guano/Chicken Fertilizer Application 20 Blood 10 0 1234567 TotalTotal NumberNumber ofof Heads,Heads, OrganicOrganic BroccoliBroccoli Watsonville,Watsonville, 20012001

200

150

100

50

0 12345 Untreated Meat Feather Blood Guano/ Meal Meal Meal Chicken TotalTotal WeightWeight ofof Heads,Heads, OrganicOrganic BroccoliBroccoli Watsonville,Watsonville, 20012001

60 50 40 30 20 10 0 12345 Untreated Meat Feather Blood Guano/ Meal Meal Meal Chicken ComparisonComparison ofof MaterialsMaterials andand TimingTiming OrganicOrganic Broccoli,Broccoli, Watsonville,Watsonville, 20012001 70 60 50 40 30 20 Weight (lbs) Weight 10 0 123456 ------Blood Meal------Guano/Chicken------45 90-45 135 45 90-45 135 4x 2x 4x 2x Chicken/GuanoChicken/Guano RateRate andand TimingTiming inin GoodGood SynchronySynchrony withwith CropCrop DemandDemand

Crop Demand

Fertilizer N Availability

Background Nitrate

Nitrate Concentration Nitrate Availability without Cover Crop

08 Weeks FertilizersFertilizers RateRate isis Adequate,Adequate, butbut TimingTiming andand MineralizationMineralization RateRate OutOut ofof SynchSynch withwith CropCrop DemandDemand (i.e.(i.e. 4x4x raterate ofof 4545 lbslbs N/A)N/A)

Crop Demand

Fertilizer N Availability

Background Nitrate

Nitrate Concentration Nitrate Availability without Cover Crop

08 Weeks FertilizersFertilizers RateRate isis Adequate,Adequate, butbut TimingTiming isis OutOut ofof SynchSynch withwith CropCrop DemandDemand (i.e.(i.e. 4x4x raterate ofof 4545 lbslbs N/A)N/A)

Crop Demand

Fertilizer mineral N

Background Mineral N

Nitrate Concentration Nitrate Availability without Cover Crop

08 Weeks IntegratingIntegrating AllAll SourcesSources ofof NitrogenNitrogen

•• AchievingAchieving effectiveeffective synchronysynchrony betweenbetween cropcrop uptakeuptake andand NN suppliedsupplied byby mineralizationmineralization fromfrom soilsoil organicorganic matter,matter, covercover cropcrop residuesresidues andand fertilizersfertilizers isis thethe challengechallenge forfor managingmanaging NN fertilityfertility ofof vegetablesvegetables inin organicorganic systemssystems EffectiveEffective SynchronySynchrony BetweenBetween MineralizationMineralization fromfrom thethe VariousVarious SourcesSources andand CropCrop DemandDemand

Crop Demand

Fertilizer 20 Mineralization

15 Cover Crop Incorporation Cover Crop Mineralization 10

5 Soil organic matter mineralization Available Nitrate (ppm) Nitrate Available

Relative Rate of N Mineralization SummarySummary

•• NitrogenNitrogen fertilizationfertilization inin organicorganic systemssystems isis trickiertrickier thanthan inin conventionalconventional systemssystems wherewhere applicationsapplications ofof readilyreadily availableavailable NN cancan bebe appliedapplied inin aa timelytimely mannermanner •• ThereThere areare typicallytypically largelarge poolspools ofof organicorganic NN inin soils,soils, butbut thethe availabilityavailability ofof thisthis NN andand thethe synchronysynchrony ofof releaserelease andand availabilityavailability forfor cropcrop productionproduction areare difficultdifficult toto predictpredict SummarySummary

•• AsAs aa result,result, organicorganic growersgrowers havehave toto developdevelop excellentexcellent skillsskills andand knowledgeknowledge toto workwork withwith thisthis systemsystem •• ThereThere maymay bebe aa tendencytendency toto overover fertilize,fertilize, especiallyespecially inin coldcold soilssoils toto makemake suresure therethere isis adequateadequate materialmaterial availableavailable forfor mineralizationmineralization