Understanding the Role of Fertilizer and Water David Wm. Reed Department of Horticultural Sciences Texas A&M University

Supplied Naturally (by H20, O2, CO2) Micronutrients or Trace Elements 1 17 Essential Elements Supplied Naturally (by H20, O2, CO2) C, H, O Macronutrients N, P, K, Ca, Mg, S Micronutrients or Trace Elements Fe, Cu, Mn, Zn, B, Mo, Cl, Ni

Where Do All the Nutrients Come From? 1 Where Do All the Nutrients Come From?   N P K Ca Mg S Fe B Other Micro Incorporated into Soil or Growing Medium - Pre-Planting complete fertilizer X ? superphosphate dolomitic lime gypsum iron sulfate micronutrient mix all Supplied Post-Planting as Granular, Liquid or Slow-Release Application Epsom salt soluble micronutr. some pesticides Cu,Mn,Zn irrigation water ppm >3-5 >1 0.3-1.5

Water: Soluble Salts (EC), pH & Alkalinity 2 Water: Soluble Salts (EC), pH & Alkalinity Collect water sample Meters Used pH: pH meter Soluble Salts or EC: conductivity meter Alkalinity: alkalinity test kit or paper Compare reading to Interpretation Table

2 Meters Used pH EC alkalinity kit

2 Meters Used Combination EC & pH Meter

Water Soluble Salts or Electrical Conductivity (EC) 3 Water Soluble Salts or Electrical Conductivity (EC) Relative Hazard None Little Moderate High Severe Electrical Conductivity dS/m or mmhos/cm 0.2 <0.7 0.7-2 2-3 >3  Soluble Salts ppm 140 <490 490 - 1400 1400 - 2100 >2100

Recommended Alkalinity Levels 4 Water Alkalinity Recommended Alkalinity Levels Minimum Maximum ppm meq/l Plugs and/or seedlings 38 0.75 66 1.3 Small pots and shallow flats 86 1.7 4" to 5" pots and deep flats 106 2.1 6” pots and long term crops 63 1.25 131 2.6

Soil/Media Soluble Salts (EC) & pH 5 & 6 Soil/Media Soluble Salts (EC) & pH Collect soil/medium sample below surface Extract with water (1:2 dilution) Filter Meters Used pH: pH meter Soluble Salts or EC: conductivity meter Compare reading to Interpretation Table

Soil/Media pH 7 Optimum pH SME 1:2 or 1:5 Dilution Extract Slurry   Extract Slurry Pour-Through Optimum pH 5.5 - 6.5 5.4 - 6.2

Soil/Media Soluble Salts (EC) 7 Soil/Media Soluble Salts (EC) Electrical Conductivity (EC) dS/m or mmho/cm SME 1:2 Dilution 1:5 Dilution Pour-Through Established plants 2.0-3.0 0.8-1.2 0.3-0.6 3.0-5.0 Seedlings, plugs 1.0-2.0 0.5-0.9 ?

Graphical Tracking pH and EC 8 Graphical Tracking pH and EC

Graphical Tracking of EC 8 Graphical Tracking of EC

Selecting a Fertilizer Based on the Form of Nitrogen 9 Selecting a Fertilizer Based on the Form of Nitrogen Nitrogen exists in two forms Ammoniacal (NH4+, urea) Nitrate (NO3-) Nitrogen form used affects Type of growth Type fertilizer, acid vs. basic pH of the soil or growing medium

Selecting a Fertilizer Based on the Form of Nitrogen 9 Selecting a Fertilizer Based on the Form of Nitrogen Form of Nitrogen Influences Type Growth and is Seasonal Nitrogen Form Type Growth Used For High Ammoniacal (>25%) lush growth larger leaves longer stems foliage plants flowering plants early warmer & summer High Nitrate (>75%) hardy plant compact growth flowering plants finishing cooler & winter

Selecting a Fertilizer Based on the Form of Nitrogen 9 Selecting a Fertilizer Based on the Form of Nitrogen Form of Nitrogen Influences Soil/Medium pH Nitrogen Form Type Fertilizer Soil/Medium Reaction High Ammoniacal (>25%) acid pH decreases & becomes more acid High Nitrate (>75%) basic pH increases & becomes more basic

Selecting a Fertilizer Based on the Form of Nitrogen 10 Selecting a Fertilizer Based on the Form of Nitrogen Acid versus Basic Fertilizers Fertilizer % NH4 / % NO3 Potential Acidity Basicity 21-7-7 acid 100 / 0 1560 0  20-18-18 73 / 27 710 15-15-15 52 / 48 261 20-10-20 38 / 48 393 20-0-20 25 / 75 40 15-5-15 28 / 72  0 135 15-0-15 13 / 87 319 15.5-0-0 Ca nitrate 6 / 94 400 13-0-44 K nitrate 0 / 100 460

Fertilizer Label Lists Potential Acidity 10 Fertilizer Label Lists Potential Acidity Label Fertilizer Analysis

Fertilizer Label Lists Potential Acidity 10 Fertilizer Label Lists Potential Acidity

11 Micronutrients in Acid Vs. Alkaline Soil (especially heavy metals: Fe, Mn, Zn, Cu) Selection of Heavy Metal Carriers based on Soil pH Iron Carrier Acid Soil Alkaline Soil Sulfates effective not very effective Chelates effective, but expensive so why use. most effective

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11 Which Chelate to Use?

Highest pH Still Effective lignosulfonate, citrate, HEDTA 11 Which Chelate to Use? Highest pH Still Effective Chelate 6 lignosulfonate, citrate, HEDTA 6.5 EDTA 7.5 DTPA (330) any pH EDDHA (138)

Fertilizer Label - Micronutrient Carriers 11 Fertilizer Label - Micronutrient Carriers

Rose Rootstocks Tolerance to Alkaline Soil 12 Rose Rootstocks Tolerance to Alkaline Soil Rose species/cultivar Chlorosis Rating (5=green to 1=yellow) R. canina 5.0 R. manettii 4.9 R. odorata 4.8 R. sp. “Mexican” R. fortuniana 4.4 R. multiflora 'Dan Whiteside' 2.7 R. multiflora ‘Brooks 56' R. multiflora 74-3 died R. 'Dr Huey'

Rose Rootstocks Tolerance to Alkaline Soil 12 Rose Rootstocks Tolerance to Alkaline Soil

13 EarthKindTM Landscape Roses (http://aggie-horticulture.tamu.edu/earthkindrose/index.html)

EarthKindTM Landscape Roses 13 EarthKindTM Landscape Roses Cultivar Flower Color Flower Type Blooming Period Ht x Wd (feet) Category Ground Covers Sea Foam creamy white double April-November 2 x 6 shrub Dwarf Shrubs Marie Daly Pink semi-double 3 x 3 polyantha The Fairy light pink 3 x 4 Small Shrubs Caldwell Pink lilac pink May- November 4 x 4 found Easy Going yellow floribunda Knock Out cherry red Livin' Easy apricot-orange Perli d'Or peach pompon Medium Shrubs Belinda's Dream 5 x 5 Climbing Pinkie pink 5 x 7 Else Poulsen Katy Road Pink 5 x 4 Mutabilis Butterfly Rose yellow, pink, crimson single 6 x 6 China

Belinda’s Dream (developed by Dr. Robert Basye) 13 Belinda’s Dream (developed by Dr. Robert Basye)