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Don’t Get Burned: Managing salts in greenhouse production Neil Mattson Assistant Professor and Floriculture Extension Specialist Presented at: New England.

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Presentation on theme: "Don’t Get Burned: Managing salts in greenhouse production Neil Mattson Assistant Professor and Floriculture Extension Specialist Presented at: New England."— Presentation transcript:

1 Don’t Get Burned: Managing salts in greenhouse production Neil Mattson Assistant Professor and Floriculture Extension Specialist Presented at: New England Greenhouse Conference Worcester, MA November 6, 2008

2 Outline Where do salts come from? General salt stress –Symptoms –Cultural Practices that cause High Salts –Sensitive Crops –Guidelines and Management Options Managing specific salt ions –Na, Cl, B, (H)CO 3, NH 4, F Nutrient Antagonisms

3 What are salts? Compounds that dissolve in water  ANIONS (-)CATIONS (+) Chloride (Cl)Ammonium (NH 4 ) Nitrate (NO 3 - )Calcium (Ca) Sulfate (SO 4 - )Iron (Fe) Magnesium (Mg) Sodium (Na) Potassium (K)

4 How are salts measured? Electrical conductivity (EC) –units: 1 dS/m = 1 mS/cm = 1 mhos/cm = 1000 µS/cm –old units: 1 mhos luckily, 1 mhos = 1 Siemen (S) PPM –conversion depends on the specific salts you are using –average of all salts: 670 ppm ≈ 1 dS/m moles/milliequivalents (SI units) –ion specific conversion (40 ppm Ca = 1 mM = 2 meq)

5 Where do salts come from? Container media, example ECs (these vary by source) SubstrateEC (dS/m) Compost (Dairy) 7-20 Peat 1.1 Sand 0.2 Soil (Mardin) 1.3 Vermicompost 1.3 Vermiculite 0.1

6 Where do salts come from? Water source –salt deposits, limestone, sea-water incursion, road salt Target: dS/m Acceptable: dS/m Massachusetts study of several greenhoues water sources (Cox, Lopes, Smith) Municipal Well (dS/m) Min Avg Max

7 Where do salts come from? Added fertilizer Example from Cal Mag fertilizer: –when applied at 200 ppm N, the water will contain an additional 1.32 dS/m of salinity

8 Salt Stress Osmotic effects –loss of osmotic gradient for water absorption –  wilting (even though substrate is moist) –If stress is prolonged may see reduced growth, smaller leaf area, shorter plants (may or may not see wilting) Toxic concentrations of ions –excess absorption of Na, Cl –excess absorption of micronutrients (B, Mn, Fe, F) (Bi)carbonate –high pH –precipitation of Ca/Mg increasing sodicity Nutrient antagonisms –an excess of one nutrient limits absorption of another

9 Outline Where do salts come from? General salt stress –Symptoms –Cultural Practices that cause High Salts –Sensitive Crops –Guidelines and Management Options Managing specific salt ions –Na, Cl, B, (H)CO 3, NH 4, F Nutrient Antagonisms

10 General high salt levels Osmotic stress –Wilting Note accumulated salts on the surface

11 General high salt levels Osmotic stress –Smaller leaf and flower size Control+3500 ppm Cl ppm Na

12 Osmotic Stress - Shorter Stems ppm N dS/m Source: Neil Mattson

13 Symptoms of Excess Soluble Salts marginal chlorosis  necrosis of older leaves

14 Symptoms of Excess Soluble Salts Death of root tips Increased Pythium susceptibility

15 Cultural Practices that Cause High Salts 50 ppm 200 ppm500 ppm N Snapdragon subirrigated with a complete fertilizer Note poor root growth in 500 ppm treatment Source: Neil Mattson

16 Liquid feed at varying concentrations Leaching event Cultural Practices that Cause High Salts Source: Neil Mattson

17 Cultural Practices that Cause High Salts Effect of irrigation method and fertilizer concentration Impatiens ‘Super Elfin Mix’ Source: Neil Mattson

18 Cultural Practices that Cause High Salts Fertility and Substrate EC Affects Growth Impatiens ‘Super Elfin Mix’ Source: Neil Mattson

19 ppm N dS/m Cultural Practices that Cause High Salts Fertility and Substrate EC Affects Growth Impatiens ‘Super Elfin Mix’ Subirrigation Source: Neil Mattson

20 Tomato ‘Sweet 100’ grown for 4 weeks at different fertility levels, was tolerant of salts to 500 ppm N Cultural Practices that Cause High Salts Source: Neil Mattson

21 High Salts from Over Fertilization, caused by –overwatering –poor drainage –root rots Cultural Practices that Cause High Salts Photos: Douglas Cox, UMass High EC from over watering

22 High Salts from CRF Use media within 1 week after incorporating CRFs Carefully measure rate during mixing – difficult to correct high salts Photo: Peter Davies, Cornell University

23 Sensitive Bedding/Potted Plants Calceolaria Celosia Fibrous begonia Impatiens Pansy Zinnia

24 Herbaceous Annuals Agastache cana Echinacea purpurea Leucanthemum x superbum ‘Alaska’ Sedum Acre

25 EC Guidelines Source: Todd Cavins et al., NCSU,

26 EC Guidelines Source: Todd Cavins et al., NCSU,

27 Monitoring EC – Pour Thru Example for Poinsettia –Establishing1.9 – 2.6 dS/m –Active Growth2.8 – 4.1 dS/m –Finishing1.9 – 2.7 dS/m Source: Todd Cavins et al., NCSU,

28 Short Term Management Options Leaching Example: Clear water application 1x / week vs. Control (constant liquid feed)

29 Long Term Management Options Decrease fertility Periodic Leach A look at fertilizer sources and salt levels  compare labels Switch water source? (Ebb and flow difficult using poor quality water for sensitive crops)

30 EC Management Using Leaching EC of Applied Water Leaching Fraction > 2 dS/m30% > 1.5 dS/m20% < 1 dS/m10% Recommended leaching fraction for container media

31 Fertilizer levels by plugs stage Stage ppm N1-2X/week Stage ppm N 1-2X/week Stage ppm N1-2X/week –mostly Nitrate based N Pour Thru EC: Young Plants are More Sensitive to Salts Souce: Styer and Koranski, Plug and Transplant Production, 1997

32 Low Fertility Plugs Stage 2< 1.5 dS/m (PourThru) Stage dS/m (PourThru) Young Plants are More Sensitive to Salts CelosiaEggplant F. Kale/CabbageLettuce PansyPepper SnapdragonTomato Souce: Styer and Koranski, Plug and Transplant Production, 1997

33 Medium Fertility Plugs Stage dS/m (PourThru) Stage dS/m (PourThru) Young Plants are More Sensitive to Salts AgeratumBrowalliaCyclamen DianthusDusty millerImpatiens LisianthusMarigoldPrimula SalviaVerbenaVinca Souce: Styer and Koranski, Plug and Transplant Production, 1997

34 Water Quality Guidelines for Plug Production pH Alkalinity60-80 ppm CaCO 3 EC< 0.75 dS/m Sodium< 40 ppm Chloride< 70 ppm Sulfates ppm OK Boron< 0.5 ppm Fluoride< 1.0 ppm Iron< 5.0 ppm Adapted from: Styer and Koranski, Plug and Transplant Production, 1997

35 Outline Where do salts come from? General salt stress –Symptoms –Cultural Practices that cause High Salts –Sensitive Crops –Guidelines and Management Options Managing specific salt ions –Na, Cl, B, (H)CO 3, NH 4, F Nutrient Antagonisms

36 Sodium / Chloride Toxicity Symptoms –Leaf margin/tip chlorosis  necrosis –Old leaves affected first –Cl typically more toxic –Foliar applied Cl > 100 ppm can also cause burn Photo: Paul Lopes, UMass

37 Chloride Sensitive Plants Roses Camellias Azaleas Rhododendrons

38 Management Options Chronic Salt Problems The case of high NaCl in water supply –Be careful of plants drying out –Blended water, reverse osmosis –Adding enough Ca, K –Avoid wetting foliage during irrigation

39 Boron Toxicity Symptoms Yellowing of leaf tips/margins  brown Old leaves affected first

40 Boron Sensitivity SENSITIVE SPECIES Threshold of source water ppm B GeraniumLarkspur PansyRosemary Zinnia MODERATELY SENSITIVE Threshold of source water ppm B CalendulaGardenia MarigoldPoinsettia Source: Maas, 1986

41 Boron Sensitivity and pH Low pH favors Boron toxicity High pH favors Boron deficiency Graph: Bailey et al., NCSU,

42 Boron Deficiency - Symptoms Growing point and new leaves affected Hard, distorted, mottled upper foliage Abortion of growing point Proliferation of branches Photo: Brian Krug, UNH

43 Boron Deficiency - Causes Petunia/Pansy plugs and flats often affected Low B in tap water High pH High Calcium Inactive roots –waterlogged –cold –high humidity Photo: Brian Krug, UNH

44 Alkalinity Alkalinity – the ability of water to neutralize acids due to the presence of dissolved alkalis: Ca(HCO 3 ) 2, NaHCO 3, Mg(HCO 3 ) 2, CaCO 3 Do not confuse with “Alkaline” which means pH level greater than 7 Reported in terms of ppm CaCO 3 (or meq; 50 ppm = 1 meq CaCO 3 ) Typically varies from ppm

45 What is Optimal Alkalinity? OptimalConcern Plugs Flats/Small Pots Large containers (> 6 inches)

46 Problems with High Alkalinity Rapid media pH rise Iron/Manganese deficiency Ca/Mg can precipate and excacerbate high Na

47 Problems with Low Alkalinity pH of container media will change more rapidly Magnesium/Calcium deficiency Low pH induced Iron/Manganese Toxicity (photo on right)

48 Crops Sensitive to High Alkalinity Iron-inefficient group (Petunia group) require a lower pH ( ) –Bacopa –Calibrachoa –Diascia –Nemesia –Pansy –Petunia –Snapdragon –Vinca

49 Crops Sensitive to Low Alkalinity Iron-efficient group (Geranium group) Require a higher pH –Marigold –Seed/Zonal Geraniums –New Guinea Impatiens –Lisianthus

50 Iron toxicity Typically from low pH in container media For water sources with high Iron (>3 ppm) –removal through flocculation / aeration Graph: Bailey et al., NCSU,

51 Correcting High Alkalinity 1)Change or blend the water source rainwater, pond water 2)Use an acidic fertilizer 3)Inject acid into irrigation water 4)Ensure Iron is available in the root- zone

52 Factors using fertilizer to adjust pH Fertilizer approach does not work well in dark/cool weather –In dark/cool weather plants accumulate ammonium (toxicity) –ammonium in the medium does not convert to nitrate (so there is less pH effect) Sometimes ammonium will not drop pH due to high lime in container media, or high water alkalinity (>300 ppm)

53 Acid Injection Acidification reduces the amount of carbonates and bicarbonates H + (from acid) + HCO 3 - (in water)  CO 2 + H 2 O

54 Which Acid to Use? Safety –Nitric acid is very caustic and has harmful fumes –Sulfuric, Phosphoric, Citric relatively safe Cost –Sulfuric is cheapest, others are 2-4 times more expensive Nutrients from Acid –Sulfuric provides S –Nitric provides N –Phosphoric provides P (but can be too much if equilibrating >100 ppm alkalinity

55 Solubility of Various Iron Forms Source: Reed, Water, Media, and Nutrition, 1996

56 Iron Chelate Products Iron Form% IronProduct Iron EDTA13% Sequestrene Fe Dissolzine EFe13 Iron DTPA10-11% Sequestrene 330 Sprint 330 Dissolzine DFe11 Iron EDDHA6% Sequesterene 138 Sprint 138 Dissolzine QFe6 Apply drenches at 5 oz/100 gal Foliar sprays at 60 ppm Fe (6-8 oz/100 gal)

57 Phytotoxicity and Foliar Iron Sprays Wash foliage with clear water soon after applying iron chelate

58 Ammonium Toxicity Symptoms: Chlorosis/necrosis of leaf margins and between veins Thick/leathery leaves Death of root tips Photos: Cari Peters

59 Causes of Ammonium Toxicity High amount in fertilizer Use of immature manure/compost Cool/wet soils inhibits conversion of Ammonium  Nitrate Low pH (<5.5) inhibits conversion and ammonium does not readily leach from most substrates

60 Crops Sensitive to Ammonium Toxicity Coleus Cosmos Geranium (Pelargonium) Salvia Zinnia Tomato Eggplant Pepper Photo: Margery Daughtrey

61 Ammonium accumulates when nitrification is inhibited

62 Solving Ammonium Toxicity Maintain Root temps ≥ 60 F Use ≤ 40% of Nitrogen ammonium Discontinue current fertilizer  switch to nitrate until conditions improve Ammonium does not readily leach, but in a pinch… –Top-dress gypsum - 1 tablespoon per 6” pot –water in with clear water –drench with 50 ppm calcium nitrate after 2 hrs

63 Fluoride Toxicity Symptoms –chlorosis of leaf tips/margins, followed by necrosis –lower leaves affected first Sources –municipal waters (>1 ppm F) –superphosphate (1600 – 2600 ppm) Susceptible plants: –Easter Lily, Gladiolus –Many foliage plants that are monocots Solutions –substitute monocalcium-phosphate –maintain higher pH

64 Outline Where do salts come from? General salt stress –Symptoms –Cultural Practices that cause High Salts –Sensitive Crops –Guidelines and Management Options Managing specific salt ions –Na, Cl, B, (H)CO 3, NH 4, F Nutrient Antagonisms

65 Excessive in Media  Low Tissue Level NH 4, Na, K, Ca, MgNa, K, Ca, or Mg PO 4 Zn or Fe CaB ClNO 3 Source: Paul Nelson Occurs when one nutrient is present in excess, and limits root absorption of another nutrient

66 Nutrient Antagonisms Ex: Chloride inhibits nitrate uptake in roses 1400 ppm Na 2100 ppm Cl Rate of nitrate uptake by roots Source: Massa, Mattson, and Lieth, 2008

67 Questions?Neil Mattson Online: Please Note – Trade names used in the presentation are for convenience only. No endorsement of products is intended, nor is criticism of unnamed products implied.


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