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

2. Supplied Naturally (by H20, O2, CO2) Micronutrients or Trace Elements1
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

3. 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

4. Water: Soluble Salts (EC), pH & Alkalinity2
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

5. 2
Meters Used pH EC
alkalinity kit

6. 2
Meters Used
Combination
EC & pH
Meter

7. 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
>2100

8. Recommended Alkalinity Levels4
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

9. 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

10. Soil/Media pH 7 Optimum pH SME 1:2 or 1:5 Dilution Extract Slurry
Extract
Slurry
Pour-Through
Optimum pH

11. 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
Seedlings, plugs ?

12. Graphical Tracking pH and EC8
Graphical Tracking pH and EC

13. Graphical Tracking of EC8
Graphical Tracking of EC

14. Selecting a Fertilizer Based on the Form of Nitrogen9
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

15. Selecting a Fertilizer Based on the Form of Nitrogen9
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

16. Selecting a Fertilizer Based on the Form of Nitrogen9
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

17. Selecting a Fertilizer Based on the Form of Nitrogen10
Selecting a Fertilizer Based on the Form of Nitrogen
Acid versus Basic Fertilizers
Fertilizer
% NH4 / % NO3
Potential
Acidity
Basicity
acid
100 / 0
1560 0 
73 / 27
710
52 / 48
261
38 / 48
393
25 / 75 40
28 / 72  0
135
13 / 87
319
Ca nitrate
6 / 94
400
K nitrate
0 / 100
460

18. Fertilizer Label Lists Potential Acidity10
Fertilizer Label Lists Potential Acidity
Label Fertilizer Analysis

19. Fertilizer Label Lists Potential Acidity10
Fertilizer Label Lists Potential Acidity

20. 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

21. 11

22. 11
Which Chelate to Use?

23. Highest pH Still Effective lignosulfonate, citrate, HEDTA11
Which Chelate to Use?
Highest pH Still Effective
Chelate 6
lignosulfonate, citrate, HEDTA
6.5
EDTA
7.5
DTPA (330)
any pH
EDDHA (138)

24. Fertilizer Label - Micronutrient Carriers11
Fertilizer Label - Micronutrient Carriers

25. Rose Rootstocks Tolerance to Alkaline Soil12
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'

26. Rose Rootstocks Tolerance to Alkaline Soil12
Rose Rootstocks Tolerance to Alkaline Soil

27. 13
EarthKindTM Landscape Roses (

28. EarthKindTM Landscape Roses13
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

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