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Soil Fertility Management in High Tunnels

Indiana Horticulture Congress, Indianapolis IN, February 12, 2019

Petrus Langenhoven, Ph.D.Horticulture and Hydroponics Crops Specialist

Outline of Today’s Talk

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• Importance of Water Quality

• Soil Testing

• Soil Health

• Soil pH and Plant Nutrient Availability

• Nitrogen Source and Soil pH

• Soil Texture

• Salinity

• Compost

• Diagnosis of Nutrient Disorders

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Irrigation Water Quality GuidelinesUpper Limit

Optimum Range(mg∙L-1 = ppm) Comments

pH 7.0 5.5 – 6.5

EC 1.25 mS∙cm-1 <0.25 closed system<1.0 open system

0.75 mS∙cm-1 for plugs and seedlings. High EC can be the result of accumulation of a specific salt which can reduce crop growth

Total Alkalinity(as CaCO3), acid-neutralizing or buffering capacity

150 mg∙L-1 0 – 100 mg∙L-1 Measures the combined amount of carbonate, bicarbonate and hydroxide ions.30 – 60 mg∙L-1 are considered optimum for plants.pH 5.2, 40 mg∙L-1 alkalinity; pH 5.8, 80 mg∙L-1 alkalinity; pH 6.2, 120 mg∙L-1

alkalinity.CaCO3 at >150 mg∙L-1 may increase the incidence of dripper clogging

Hardness(amount of dissolved Ca2+ and Mg2+)

150 mg∙L-1

>60 mg∙L-1 Ca>25 mg∙L-1 Mg

50 – 100 mg∙L-1 Indication of the amount of calcium and magnesium in the water. Calcium and magnesium ratio should be 3 – 5 mg∙L-1 calcium to 1 mg∙L-1 magnesium. If there is more calcium than this ratio, it can block the ability of the plant to take up magnesium, causing a magnesium deficiency. Conversely, if the ratio is less than 3-5 Ca:1 Mg, the high magnesium proportion can block the uptake of calcium, causing a calcium deficiency. Equipment clogging and foliar staining problems above 150 ppm

Bicarbonate Equivalent (HCO3

-)122 mg∙L-1 30 – 50 mg∙L-1 Help to stabilize pH. Increased pH and can lead to Ca and Mg carbonate precipitation

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Irrigation Water Quality GuidelinesUpper Limit

Optimum Range(mg∙L-1 = ppm)

Comments

Calcium 120 mg∙L-1 40 – 120 mg∙L-1

Magnesium 24 mg∙L-1 6 – 24 mg∙L-1

Iron 5 mg∙L-1 1 – 2 mg∙L-1 >0.3 mg∙L-1, clogging; 1.0 mg∙L-1, foliar spotting and clogging; above 5.0 mg∙L-1, toxic. Could lead to iron precipitates resulting in plugging of irrigation system emitters

Manganese 2 mg∙L-1 0.2 – 0.7 mg∙L-1 >1.5 mg∙L-1 emitter blockage can occur

Boron 0.8 mg∙L-1 0.2 – 0.5 mg∙L-1

Zink 2 mg∙L-1 0.1 – 0.2 mg∙L-1

Copper 0.2 mg∙L-1 0.08 – 0.15 mg∙L-1

Molybdenum 0.07 mg∙L-1 0.02 – 0.05 mg∙L-1

Sulfate 240 mg∙L-1 24 – 240 mg∙L-1

(60 to 90 mg∙L-1)If the concentration is less than about 50 ppm, supplemental sulfate may need to be applied for good plant growth. High concentrations of sulfides can lead to build-up of sulfur-bacteria in irrigation lines that could clog emitters.

Chloride 70 mg∙L-1 0 – 50 mg∙L-1 Concern, above 30 mg∙L-1 for sensitive plants

Sodium 50 mg∙L-1 0 – 30 mg∙L-1 If the SAR is less than 2 mg∙L-1 and sodium is less than 40 mg∙L-1, then sodium should not limit calcium and magnesium availability

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Fertility Management Tests Used by Growers to Determine Fertilizer Application Needs

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Results from 2012 survey where 89 vegetable farms in Indiana responded

• Over 35% don’t use any test

• Almost 20% use soil and leaf tests

• Very few farms use leaf tests

• 42% of farms use soil tests0

10

20

30

40

50

60

70

80

90

100

avg farm small medium large

Per

cen

tage

of f

arm

ers

soil test leaf test soil & leaf neither

Data source: Purdue 2012 survey of MarketMaker Growers

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What’s in Indiana Soil?2017 Averages Optimum for

vegetablesNIN

NEIN

NWIN

SIN

SEIN

SWIN

Organic Matter (%) 3-6 3.5 3.3 3.9 2.6 2.7 2.5Nitrogen, ppm (NO3-N and NH4-N) 20-40 26.6 22.2 31.5 29.0 29.4 26.4Phosphorus (P1), ppm (available) 25-50 44 43 47 34 33 35Phosphorus (P2), ppm(available and part of reserve)

40-60 64 68 59 56 64 55

Bicarbonate P, ppm (pH >7.3, availability in calcareous soils)

>15 46 48 42 41 41 38

Potassium (K), ppm 150-300 140 140 140 124 126 121Potassium (K), % Base Sat. 1-5 3.9 3.9 4.0 3.5 3.3 3.6Magnesium (Mg), ppm 60-120 263 264 260 216 249 163Magnesium (Mg), % Base Sat. 10-40 20.9 20.9 20.9 17.7 19.8 14.4Calcium (Ca), ppm 1000-2500 1362 1379 1334 1303 1339 1245Calcium (Ca), % Base Sat. 40-80 62.2 63.2 60.5 65.2 63.8 67.4

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What’s in Indiana Soil?

2017 Averages Optimum for vegetables

NIN

NEIN

NWIN

SIN

SEIN

SWIN

pH (Mineral soil) 6.0-7.0 6.5 6.6 6.4 6.5 6.5 6.4CEC, meq/100g of soil 5-35 10.7 10.7 10.7 9.9 10.4 9.2Sulfur (S), ppm 10-20 8 8 7 7 7 8Zinc (Zn), ppm (def. high P and pH) 1-3 3.6 3.5 3.7 3.0 3.0 3.1Manganese (Mn), ppm (def. high pH) 6-12 36 37 33 51 47 58Iron (Fe), ppm (def. high pH) 11-16 45 44 46 43 41 44Copper (Cu), ppm (def. low pH, muck soil) 0.5-1.5 1.5 1.6 1.4 1.6 1.8 1.5Boron (B), ppm (def. high pH) 0.7-1.0 0.4 0.5 0.4 0.4 0.4 0.3Molybdenum, ppm (def. low pH) 0.11-0.20

Why is Soil Health Important?

Soil Health

Society/regional focus• Soil carbon sequestration• Water quality/retention• Pollutant detoxification• Increased biodiversity

Producer/owner focus• Soil organic matter• Economic viability• Climate resilience

Producer focus• Inputs and labor• Pest and disease

resistance• Yield• Shelf life

Consumer focus• Nutrition• Flavor, Aroma• “Clean” (toxin free)• Shelf life

Soil Health is CentralFood, Crop and Ecosystem HealthIs Dependence Upon Soil Health

Modified from Bionutrient Food Association

Slide provided by L. Hoagland, Purdue University8

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What Factors Contribute to Soil Health?

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Fairly well understood but

less often applied• Bulk density• Aggregate stability• Water infiltration

Well understood and most often applied• Soil pH• Cation exchange capacity (CEC)• Available mineral nutrients• Electrical conductivity (EC)

Least understood and applied, but could be the most important

Source: http://soilhealth.cals.cornell.edu/training-manual/

Organic Soils, pH 5.3 to 5.8 Mineral Soils, pH 6.0 to 7.0

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Phosphorus availability affected by pH

13Source: https://www.pioneer.com/home/site/us/agronomy/phosphorus-behavior-in-soil/

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Urea and Soil pH

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Conversions between nitrogen forms and effect on root-zone pH

15Source: Neil Mattson. 2009. Nitrogen: All forms are not equal

Effect of N source on soil pH

16Source: Zazoski, 1994

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Read the label

Potential Acidity or Basicity of fertilizer Sources

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Source: Neil Mattson. 2009. Nitrogen: All forms are not equal

Effect of Soil Texture on Nutrient Availability, Water Holding Capacity and Irrigation

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High clay content increases CEC and

ability to hold nutrients

High clay content increases CEC and

ability to hold nutrients

Sandy soil, large pore

spaces, more leaching, lower

CEC

Sandy soil, large pore

spaces, more leaching, lower

CEC

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Soil salinity, salt accumulation

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• Covering the soil with a high tunnel prevents natural rainfall from washing or leaching excess nutrients and soluble salts from the soil• Can lead to very dry soil• Can elevate soil temperature and prevent soil from freezing, which increases soil microorganism activity• Soluble salts level can build up, especially in the top 2-4 inches at the end of the cropping period

• Most sensitive crops are strawberries and green beans• Salt build up can be prevented by:

• Avoiding excessive application of organic materials like compost and manure• Diligently manage soluble fertilizers and application• Avoid fertilizers with high salt index, especially Potassium chloride, Ammonium nitrate, Manure salts• Application of sufficient irrigation water• Improved drainage

• Leach salt with several inches of water i.e. sprinkler irrigation or removal of plastic in winter• Soils heavily amended with compost and that have very high organic matter content, makes it more difficult to

manage nitrogen• Large flushes of nitrogen can occur in warm soils or when soils are rewetted after a dry period

Benefits of adding organic matter to soil

• Provides nutrient reservoir for N, P, S, Cu and Zn

– released when organic matter decomposes

• Retains nutrients in an available form

• Increase cation exchange capacity

• Increases aggregate formation (crumb-like structure that gives soil tilth)

• Increases soil porosity (alter water retention and infiltration)

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Quality and characteristics of compost can vary dramatically. Is it Plant- or Manure based Compost?

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Source: Biernbaum, 2013. High Tunnel Soil and Water

COMPOST• Compost is maturing over time. Is it stored outside or inside, dry or moist, cold or warm?• Prevent leaching of nutrients from compost• Only apply compost after the thermophilic phase has been completed. Unfinished compost

may contain plant pathogens and weed seed bank, and may compete with plant roots for nitrogen as breakdown continues in the soil

• Recommended C:N ratio for finished compost is 15:1 to 18:1 • Compost addition 2-3 times per year for first 4 years. Apply at least 1 week before

transplanting or seeding• Prepare beds, add compost to surface layers (helps with water absorption and germination)• Rate is dependent on the type of compost and nitrogen content• Can range from 1.6 to 5.5 cubic ft. per 100 sq. ft. (12 to 40 gallons per 100 sq. ft.)• More frequent application and the better the soil and crop growth, the lower the application

rate22

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Impact of Soil Amendments on Soil Quality• Green manure treatment increased soil quality in both open field and high

tunnel production systems• Soil quality declined in urea treated plots, especially in the high tunnel• Soil pH: urea < green manure and chicken litter treatments• Soil EC (salt): high tunnel > open field

How could these changes

affect pathogen

dynamics?

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Slide provided by: L. Hoagland, Purdue

University

Impacts on susceptibility to R. solani

Rhizosphere soil collected for shotgun metagenomics and metranscriptomic assays

0.00

0.10

0.20

0.30

0.40

0.50

0.60

Dry Root

CNT UR GM CM CNT UR GM CM

aa

aa

a

b

bb

High TunnelOpen Field AB

(Hoagland et al. in prep)

a

Snap

 bea

n biomass (g)

• Soils collected from the high tunnel were more susceptible to R. solanithan from the open field

• HT green manure treatment was less susceptible to R. solani than the other treatments

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Slide provided by: L. Hoagland, Purdue University

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Impacts on active microbial community structure• Several microbial taxa that is often implicated in pathogen

suppressive activity was greater in GM treatment• Actinomycetales, Bacillales and Pseudomanadales

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Urea GM

Relative abundance of dominant microbial in the rhizosphere by Order

Phylum Class Order Family Genus Urea (OTU’s)

Green manure (OTU’s)

Actinobacteria Actinobacteria Actinomycetales Streptomycetaceae Streptomyces 15761 91297Actinobacteria Actinobacteria Actinomycetales Micrococcaceae Arthrobacter 0 74621Actinobacteria Actinobacteria Actinomycetales Proprionibacterineae Nocardioides 0 69552Firmicutes Bacilli Bacillales Bacillaceae Bacillus 25217 86162Proteobacteria Gammproteobacteria Pseudomanadales Pseudomonadaceae Pseudomonas 0 35078

Actino’s

Antagonistic activity of Actinomycetes (right) against a fungal pathogen (left)-Production of antibiotics

OTU – Operational Taxonomic Unit

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(Hoagland et al. in prep)

Slide provided by: L. Hoagland, Purdue University

Impacts on active soil microbial community structureEnterobacteriaceae, including several genera of potential enteric bacteria, much greater in the urea treatment

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Urea GM

Relative abundance of dominant microbial in the rhizosphere by Order

Entero’s

Phylum Class Order Family Genus Urea (OTU’s)

Green manure (OTU’s)

Proteobacteria Gammproteobacteria Enterobacteriales Enterbacteriaceae Escherichia/Shigella 391504 182033Proteobacteria Gammproteobacteria Enterobacteriales Enterbacteriaceae Salmonella 166046 80493Proteobacteria Gammproteobacteria Enterobacteriales Enterbacteriaceae Enterobacter 112383 30891Proteobacteria Gammproteobacteria Enterobacteriales Enterbacteriaceae Cronobacter 54589 0Proteobacteria Gammproteobacteria Enterobacteriales Enterbacteriaceae Yersinia 46807 0

(Hoagland et al. in prep) 26Slide provided by: L. Hoagland, Purdue University

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Other Testing Resources

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• Plant tissue analysis• Can be helpful to diagnose in-season plant growth problems

• Petiole (leaf stem) sap testing (N and K) • Horiba Cardy or Laqua meters are popular equipment for sap-testing

• Meters are sensitive to temp. changes; frequent recalibration is necessary through the day

• Not as precise as lab tests

• Relatively simple, give immediate results, and are particularly useful for making timely adjustments in fertilizer application rates when using fertigation

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Key to Visual Diagnosis of Nutrient Disorders

Source: http://www.haifa-group.com/knowledge_center/crop_guides/tomato/plant_nutrition/nutrient_deficiency_symptoms/

‐ K ‐ N ‐ P

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29Source: Bierman P.M. and C.J. Rosen. 2005. Nutrient Management for fruit and vegetable crop production. Diagnosing Nutrient Disorders. University of Minnesota. http://lewis-mg-mrc.org/yahoo_site_admin/assets/docs/KeyToNutrientDisorders.46154313.pdf

**Symptoms of sulfur deficiency usually occur on upper leaves first, but a general yellowing of the entire plant may occur under prolonged deficiency conditions

Literature Resources

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• Soil quality for Environmental Health. University of Illinois at Urbana-Champaign. http://soilquality.org/home.html

• Comprehensive Assessment of Soil Health. Cornell University. https://soilhealth.cals.cornell.edu/

• NRCS Soil Quality Test Kit…. https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/health/assessment/?cid=nrcs142p2_053873

• Nutrient Management for Commercial Fruit & Vegetable Crops in Minnesota (BU-05886). University of Minnesota. https://conservancy.umn.edu/handle/11299/51272

• Michigan State University, Extension Bulletin E2934. Nutrient recommendation for Vegetable Crops in Michigan. http://msue.anr.msu.edu/resources/nutrient_recommendations_for_vegetable_crops_in_michigan_e2934

• Knott’s Handbook for Vegetable Growers, 5th Edition. http://extension.missouri.edu/sare/documents/KnottsHandbook2012.pdf

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THANK YOUQuestions?

Contact details:

Dr. Petrus Langenhoven

Horticulture and Hydroponics Crop Specialist

Department of Horticulture and Landscape Architecture

Purdue University

Tel. no. 765-496-7955

Email: plangenh@purdue.edu31