Advanced ph management. Outline. Iron deficiency at high substrate-ph

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1 Advanced management Outline Understand how substrate affects chemical solubility, nutrient availability and plant growth Paul Fisher 1 Manage factors that affect substrate Fertilizer level Water quality Ammonium :nitrate ratio Iron form 2 Iron deficiency at high substrate Chlorosis, often interveinal, in new tissue Iron deficiency at high (>6.4 in ironinefficient plants) Iron required to produce chlorophyll (green) Low mobility within plant Very common, especially at low fertilizer level Iron/manganese toxicity at low substrate Excess micronutrient accumulates in the tissue Chlorosis and necrosis occurs in older leaves Less common issue, in ironefficient crops 3 4 of the growing media ( Substrate ) affects... Nutrient solubility Uptake by Plant Plant health too much toxicity too little deficiency ppm iron ppm iron Chlorophyll ( g.mg 1 ) (A) Media Iron (B) Tissue Iron (C) Total Chlorophyll Substrate affects Nutrient solubility Uptake by Plant Plant health 5 Media Petunia hybrid 6

2 Substrate affects micronutrient solubility and plant health Before we get too far management is not that complex Maintain substrate around , and you will be fine. But this is an advanced session. Impatiens Substrate For more info 7 8 Greenhouse Training Online courses BMP account of Back Pocket Grower Designed for greenhouse employees in the US and internationally English & Spanish, Four weeks Classes accessible any time of day Customized certificate of completion $2 per person (SA discount $16) Go to backpocketgrower.org with your browser. Looks best on a mobile device. password Topic Start date End Date Level Greenhouse 11 3May 24Jun Nutrient Management 1 (Intro) 18Jul 12Aug Nutrient Management 2 (Advanced) 22Aug 16Sep Disease Management 26Sep 21Oct Weed Management Copyright 216. Paul 24Oct Fisher, 18Nov 9 Log in (BMP account for 216: gatorbait) Sign In 1 Training Tools solubility curve: Did you know Based on one mix (peat/bark/sand/vermicultite) and one fertilizer containing STEM (sulfate micronutrients) and dolomitic lime? Why do different nutrients have the reported shape in the curve? 11 12

3 ppm NitrateN Nitrate is not affected by 1% nitraten fertilizer, no plants Managing nitraten is Copyright a supply 216. (EC) Paul Fisher, issue, not a issue 13 Ammonium tends to be nitrified (turned into nitrate) by bacteria at high ppm Nitrogen 1% ammoniumn fertilizer AmmoniumN 5 NitrateN Much of the acidity of ammonium can result from microbes 14 Ammonium toxicity with high University NH of Florida 4 fertilizer, low, cool & wet Phosphorus reacts with calcium at high ppm PhosphateP Same fertilizer with different lime types Calcium hydroxide Magnesium hydroxide ppm Potassium Potassium is not affected by, but coconut coir can contribute K Same nutrients with different media types Peat_coir Peat_bark Peat_perlite Peat_vermiculite Low P can be an issue Copyright at high 216. Paul Fisher, 15 Media components can Copyright sometimes 216. Paul Fisher, add nutrients 16 Increasing Calcium at high is because of the lime source, not solubility Magnesium has the same trend as Calcium Same fertilizer with different lime types Same fertilizer with different lime types ppm Calcium Calcium hydroxide Magnesium hydroxide ppm Magnesium Calcium hydroxide Magnesium hydroxide Raising per se will not increase calcium availability 17 Adding calcitic limestone, calcium nitrate, or gypsum increases Ca Raising per se will not increase magnesium availability 18 Adding dolomitic limestone, mag nitrate, or mag sulfate increases Mg

4 Lime Many factors affect substrate Substrate and EC crop cycle check up Plug squeeze each week of crop Low fert High fert Nitrate NO 3 Ammonium NH + 4 Species Petunia Geranium BASIC Factors (Raise ) balance ACID Factors (Lower ) 19 2 and EC crop cycle check up Major factors during propagation Compartment H2 H1 H1 H5 H1 Stick/Sow week: Week 12 Week 11 Week 1 Week 9 Week 8 Crop age: Week Week 1 Week 2 Week 3 Week 4 plug squeeze: EC plug squeeze: Plant appearance: Ffertilizer type and concentration: Good Rooted, slight yellowing new leaves Good tone clear water clear water ppm N +1.5 ppm Fe Somewhat soft, well rooted ppm N +1.5 ppm Fe Soft, well rooted, stretched ppm N +1.5 ppm Fe21 Mist phase Lime reaction Substrate & cation exchange capacity (CEC) Electrical conductivity (EC) Water quality Finishing phase Lime residual Nitrogen form & concentration Plant Species 22 Lime Many factors affect substrate Substrate EC EFFECTS: High and low salts are common at the end of the mist phase Low fert High fert Nitrate NO 3 Ammonium NH + 4 Species Petunia Geranium BASIC Factors (Raise ) balance ACID Factors (Lower ) 23 24

5 Why? Because increases as EC decreases with leaching Leaching with clear water washes out salts and raises = Exchange sites Soil solution Peat particle Ca ++ Ca EC: Preplant salts (especially Calcium) drop Adding fertilizer will drop Cation Substrate Control (water) 5.8 Ammonium 5.5a Potassium 5.5a Peat particle = Exchange sites Soil solution Magnesium 5.5a Calcium 5.2b EC EFFECTS: What should you do about this high /low EC issue? Lime Many factors affect substrate Substrate Low fert High fert Nitrate NO 3 Ammonium NH + 4 Species Petunia Geranium Avoid excess leaching Fertilizer at end of mist phase 29 BASIC Factors (Raise ) balance ACID Factors (Lower ) 3

6 WATER QUALITY: Solution What is? Low High Can be measured with a meter <7 acid 7 neutral >7 basic H O H H O _ Affects the solubility and activity of chemicals and fertilizer in solution H 2 O Water OH Base Little effect on substrate 31 Low values are ACID, high values are BASIC 32 Most agrichemicals are more effective at an acidic, for example chlorine % Total Chlorine 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % Hypochlorous acid HOCl (strong sanitizer) HOCl Hypochlorite OCl (weak sanitizer) Injecting acid can reduce chlorine cost, increase sanitizing 33 effect, and reduce phytotoxicity risk. Control the of your spray tank for maximum effect of agrichemicals Pesticide Optimum range Azadirachtin (Azatin) Abamectin (Avid) Acephate (Orthene) Thiophanate methyl (Cleary s 3336) Chlorothalonil (Spectro) Fenhexamid (Decree) Ancymidol (ARest) Ethephon (Ethrel, Florel, Pistill) Less than 5. OCl extension.umass.edu/floriculture/factsheets/effectsph pesticidesandgrowthregulators 34 Correct and hardness (Ca + Mg) of spray tank solutions WATER: Affects Substrate Purdue University Extension Impact of water quality on pesticide performance ( edu/extmedia/ppp/ppp86.pdf) Use acid or other water conditioners Run a jar test to check complete dissolution 35 Water Volume (in ml) of.164 N H 2 SO 4 Added High Water Low Water Can NOT be measured with a meter Can have a large effect on substrate Often termed as bicarbonates Think of as dissolved limestone 36

7 212 Water is like dissolved limestone units Main ions that come under the term : Bicarbonates [HCO 3 (Ca, Mg, Na)] 2 Carbonates [CO 3 (Ca, Mg, Na)] Milliequivalents (meq/l) ppm alkalinity (CaCO 3, or CCE) ppm bicarbonate or HCO 3 Limestone (similar reaction) CaCO 3 + 2HPeat H 2 O + CO 2 + CaPeat Water quality Irrigating with high alkalinity (>15 ppm CaCO 3 ) is like applying limestone to the substrate with each irrigation. Substrate rises over time Water alkalinity is a much stronger base than water Example plant grown in 1 liter container Irrigated with 1 liter of water per week for 15 weeks With a water that has 9 and 2 ppm CaCO 3 alkalinity factor Amount Milliequivalents of base added per pot Water base Control alkalinity with mineral acid How much to add? Use online AlkCalc from University of New Hampshire Sulfuric (adds S) Phosphoric (adds P) Nitric (adds N) Water alkalinity 2 ppm CaCO 3 6 base Lime (CaCO 3 ) 3 kg/m 3 6 base 39 Bring water down to around 6 (~ 2 meq/l or 1 ppm CaCO 3 for some alkaline water sources) 4 Lime Many factors affect substrate Substrate Low fert High fert 7.84% ammonium= 2% total N 39% of nitrogen in ammonium form Nitrate NO 3 Ammonium NH + 4 Species Petunia Geranium BASIC Factors (Raise ) balance ACID Factors (Lower ) 41 42

8 FERTILIZER: Potential ity or Basicity NP 2 O 5 K 2 O (NH 4 N + UreaN) / Total N Potential reaction in lb/ton (A=acid, B=base) 1 lb/ton =.5 kg/tonne % A % A % B % B 42 Fertilizers containing more than 2% of N as ammonium tend to be acidic. The Calcium Carbonate Equivalency (CCE) of a fertilizer is its potential to change after it is applied, because of root uptake or microbes. Can not be measured in the fertilizer solution with a meter 43 Ammonium Fertilizers Plant uptake (charge balance) Ammonium NH Ammonium Fertilizers Microbes quickly convert ammonium to nitrate (nitrification) when is above 6 Nitrification by soil microbes Nitrate NO 3 Ammonium NH NH 4 N (ppm) found in the substrate Ammonium (NH 4 N) in the substrate 7 Week 8 Week 12 Week Rootsubstrate 5% Copyright NH 4 N % Paul NH Fisher, 4 N 3% NH 4 N 46 Nitrate Fertilizers Nitrate Fertilizers Plant uptake (charge balance) Nitrate NO 3 Base (hydroxyl) OH Base (bicarbonatel) HCO 3 47 Plant uptake (charge balance) does not always change Nitrate NO 3 Potassium K + no change 48

9 Match your fertilizer to your alkalinity NP 2 O 5 K 2 O (NH 4N + UreaN)/ Total N Potential reaction in lb/ton (A=acid, B=base) Match to this ppm CaCO 3 of water alkalinity % A ppm 212 4% A 46 2 ppm % B 1 ppm % B 42 5 ppm High alkalinity can be balanced with high ammonium. BUT: lush growth, ammonium toxicity in winter, and not effective when plants are small, substrate wet & cold. If alkalinity is greater than 15 ppm CaCO 3, acid usually also needed. 49 of the growing media ( Substrate ) affects... Nutrient solubility Uptake by Plant Plant health too much toxicity too little deficiency 5 Inorganic Fe solubility Inorganic iron, such as iron sulfate (FeSO 4 ), rapidly decreases in solubility as increases 4 Highly soluble Fe 3+, Fe 2+ 7 Highly insoluble Fe(OH) 3 51 Lindsay (1979) 52 Iron solubility and chelates 1 ppm iron from IronEDTA Synthetic chelates Most common fertilizers: FeSO 4, FeEDTA (constant) FeDTPA, FeEDDHA (corrective) (Norvell, Copyright 1991) 216. Paul Fisher, 53 (W.A. Norvell., 1971) Impatiens media

10 At low (5.1) all iron forms soluble ppm IronEDDHA At high (7.) iron form matters ppm IronEDDHA IronEDTA IronEDTA Iron sulfate Iron sulfate Calibrachoa, high 7.2 Control ppm FeEDDHA At high, increasing micronutrient level can lead to improved growth and appearance ppm iron.5ppm 1ppm 2ppm ( 7.) FeEDTA FeSO 4 Adding.5 ppm ironeddha is a costeffective method for ironinefficient crops University of Florida 57 Consider having a separate injector for micronutrients v NPK. Control growth with N or P, maintain color with Mg and micros. 58 correction to rescue stressed crops Options to correct high substrate 1. Make sure substrateec is not low. Sometimes high is simply because the substrate is leached out. If EC is low, add fertilizer. 2. Ammonium fertilizer and low water alkalinity. Lower over 12 weeks. Have ammonium nitrate or ammonium sulfate on hand. First check substrate and EC. Check root health. Usual disclaimer: Test on small group of plants first. Dead leaves won t come back to life Correct micronutrient deficiencies. Mask symptoms with an iron drench at 2 ppm iron. Have ironeddha (Sprint 138 or similar) on hand. 4. Consider acid drenches in extreme cases. Ferrous iron sulfate drenches at 12 g/1 L rapidly reduce but foliar phytotoxicity is likely. 6

11 IronEDDHA is most effective iron source at high ppm iron IronEDDHA Iron drenches 33 grams/1 Liters IronEDDHA 2 ppm iron (best), OR IronDTPA 37 ppm iron (OK) IronDTPA Apply with generous leaching. Immediately wash foliage. Do not apply to ironefficient plants. Control Calibrachoa 7 (1 days after application, days after planting) 62 Phytotoxicity from iron drench (4 ppm, ironeddha) Options to correct low substrate Flowable lime: Effective, messy to apply, may not be available in your area Potassium bicarbonate or carbonate: Effective, repeat applications often required, can raise EC Recommended for rapid correction Nitratebased fertilizer: Longerterm, helps prevent low problems, not suitable for rapid increase in. Most effective in combination with alkaline irrigation water. Hydrated lime in solution or topdress: Can be inconsistent. Easy to source and low cost Tips for Potassium bicarbonate In conclusion Can be delivered through emitters or ebb and flood. management is not that complex Apply in cool weather and immediately rinse foliage. Maintain around , and you will be fine. One day after application, apply a basic fertilizer (high nitrate) with moderate leaching to wash out salts and to reestablish nutrient balance. Leaf distortion from potassium bicarbonate residue Understanding how factors interact will improve your management 65 66