Upload
diana-trindle
View
221
Download
2
Tags:
Embed Size (px)
Citation preview
Managing Managing Greenhouse Greenhouse
NutritionNutritionPaul A. Thomas and Bodie V. Paul A. Thomas and Bodie V.
Pennisi Pennisi Extension Horticulture Specialists Extension Horticulture Specialists
- Floriculture- FloricultureThe University of GeorgiaThe University of Georgia
Modern Modern ProductionProduction
Modern Modern ProductionProduction
Growers Growers should should
NOT NOT have have
nutritionnutritional al
problemproblemss
Why do we still have Why do we still have problems?problems?
Focus on solving problemsFocus on solving problems
Need to shift focus to Need to shift focus to PREVENTING problemsPREVENTING problems
What to What to Look ForLook For
Things that will impact plant nutritionThings that will impact plant nutrition Chemical characteristicsChemical characteristics
pH - water, fertilizer solutionpH - water, fertilizer solution EC - water, fertilizer solutionEC - water, fertilizer solution alkalinity - water, fertilizer solutionalkalinity - water, fertilizer solution
Nutritional valueNutritional value macronutrients, micronutriensmacronutrients, micronutriens
Non-nutritional elements – possible toxicitiesNon-nutritional elements – possible toxicities Na, Cl, F, AlNa, Cl, F, Al
Expressed in ppm, mg/L, meq/LExpressed in ppm, mg/L, meq/L
Expressed as CaCOExpressed as CaCO3 3 or HCOor HCO33--
AlkalinityAlkalinityAlkalinityAlkalinity
Irrigation water should have Irrigation water should have an alkalinity of less than 100ppm; an alkalinity of less than 100ppm; if higher than 150 ppm, if higher than 150 ppm, acidification is neededacidification is needed
A measure of water’s ability to A measure of water’s ability to neutralize acids – a buffering abilityneutralize acids – a buffering ability
Mostly carbonates and Mostly carbonates and bicarbonates – associated with Ca bicarbonates – associated with Ca and Mg (limestone) and Mg (limestone)
May cause pH to rise in media May cause pH to rise in media over time, especially in small over time, especially in small containerscontainers
AlkalinityAlkalinityAlkalinityAlkalinity
Note: Alkalinity “controls” Note: Alkalinity “controls” pHpH
Must know alkalinity to Must know alkalinity to manage pHmanage pH
The Goal Is To The Goal Is To Achieve A Achieve A
Stable Medium Stable Medium pH Over TimepH Over Time
The Goal Is To The Goal Is To Achieve A Achieve A
Stable Medium Stable Medium pH Over TimepH Over Time
Alkalinity TermsAlkalinity TermsAlkalinity TermsAlkalinity Terms
Milliequivalents Milliequivalents alkalinity alkalinity
mg/liter or mg/liter or ppm CaCOppm CaCO33 of alkalinity of alkalinity
11
22
33
44
55
mg/liter or mg/liter or ppm ppm
bicarbonate bicarbonate
5050
100100
150150
200200
250250
6060
122122
183183
244244
305305
Sample ASample A Sample BSample B
pH = 9pH = 9 pH = 7pH = 7
One drop of acid to get pH 6One drop of acid to get pH 6 Ten drops of acid to get pH 6Ten drops of acid to get pH 6
The Effect of Water Alkalinity on Media The Effect of Water Alkalinity on Media pH and Acid RequirementpH and Acid Requirement
The Effect of Water Alkalinity on Media The Effect of Water Alkalinity on Media pH and Acid RequirementpH and Acid Requirement
Little or no effect on the Little or no effect on the growing medium pHgrowing medium pH
Increases growing medium Increases growing medium pHpH
Alk = 50 Alk = 50 ppmppm Alk = 300 Alk = 300 ppmppm
CaMg(COCaMg(CO33))22
Dolomitic Dolomitic
limestonelimestone
CaCa2+2+ + Mg + Mg2+2+ + 2CO + 2CO332-2-
HardnessHardness
AlkalinityAlkalinity
Hardness and Alkalinity Generally Hardness and Alkalinity Generally Go Hand-In-Hand but They Are Go Hand-In-Hand but They Are
NOT One and the SameNOT One and the Same
You Can Use the Water Hardness You Can Use the Water Hardness to Estimate Its Alkalinityto Estimate Its Alkalinity
Calcium and magnesium are the major Calcium and magnesium are the major contributorscontributors
“ “hard water” has a high Ca and/or Mghard water” has a high Ca and/or Mg “ “hard water” is hard water” is generallygenerally associated associated with high alkalinitywith high alkalinity can have hard water and low can have hard water and low alkalinity – water high in CaClalkalinity – water high in CaCl2 2 and/orand/or
MgClMgCl22
HardnessHardnessHardnessHardness
If you have hard water:If you have hard water: check Ca and Mg concentrationscheck Ca and Mg concentrations
if high use less limeif high use less lime monitor pH !monitor pH !
check Ca : Mg ratiocheck Ca : Mg ratio ideal ratio is 3:1 if expressed in meq/Lideal ratio is 3:1 if expressed in meq/L ideal ratio is 5:1 if expressed in ppmideal ratio is 5:1 if expressed in ppm
HardnessHardnessHardnessHardness
HH22COCO332CO2CO332- 2- + 2H + 2H ++
HH22O + COO + CO22
Substrate Substrate AcidityAcidity
AlkalinityAlkalinity
Both the alkalinity and Both the alkalinity and the acidity are neutralizedthe acidity are neutralized
6.0
6.5
7.0
7.5
0% 15% 35% 55%
Poinsettia Crop 10 Weeks After PlantingPoinsettia Crop 10 Weeks After Planting(adopted from (adopted from Greenhouse GrowerGreenhouse Grower, January 2001, p.72), January 2001, p.72)
Leaching FractionLeaching Fraction
Med
ia p
HM
edia
pH
The more water applied to the crop, the greater The more water applied to the crop, the greater effect high alkalinity water will have on media pH.effect high alkalinity water will have on media pH.
Initial media pH = 6.0Initial media pH = 6.0Water alkalinity = 320 ppm CaCOWater alkalinity = 320 ppm CaCO33
pH affects the solubility of fertilizers, pH affects the solubility of fertilizers, and the efficacy of pesticides and and the efficacy of pesticides and growth regulators.growth regulators.
the higher the water pH the less the higher the water pH the less soluble these materials aresoluble these materials are
pH pH pH pH
Dealing With Dealing With High And Low High And Low
Water Water AlkalinityAlkalinity
Dealing With Dealing With High And Low High And Low
Water Water AlkalinityAlkalinity
Action Steps To Correct High AlkalinityAction Steps To Correct High AlkalinityAction Steps To Correct High AlkalinityAction Steps To Correct High Alkalinity
reverse osmosis
acid injection
acid fertilizer and/or
none
less lime
Alkalinity Alkalinity (ppm) (ppm)
bicarbonatebicarbonate
480480
180180
120120
If acid injection required, use the Alkalinity If acid injection required, use the Alkalinity Calculator found on:Calculator found on:
www.ces.ncsu.edu/depts/hort/floriculture/www.ces.ncsu.edu/depts/hort/floriculture/software/software/
Correcting High AlkalinityCorrecting High AlkalinityCorrecting High AlkalinityCorrecting High Alkalinity
Most commonly used acids: sulfuric, Most commonly used acids: sulfuric, phosphoric, nitric.phosphoric, nitric.
Need to consider the extra phosphorus (P), Need to consider the extra phosphorus (P), nitrogen (N), or sulfur (S) in the acid when nitrogen (N), or sulfur (S) in the acid when selecting fertilizer.selecting fertilizer.
3.4 fl oz of 85% phosphoric acid/100 gal 3.4 fl oz of 85% phosphoric acid/100 gal adds 122 ppm P to the irrigation wateradds 122 ppm P to the irrigation water
If acid is changed, nutritional program needs If acid is changed, nutritional program needs to be re-evaluated.to be re-evaluated.
Correcting High AlkalinityCorrecting High AlkalinityCorrecting High AlkalinityCorrecting High Alkalinity
Other FactorsOther Factors
SalinitySalinitySalinitySalinity
Total Dissolved Salts (TDS) – all salts Total Dissolved Salts (TDS) – all salts present in the water (1 mMho/cm=640 ppm)present in the water (1 mMho/cm=640 ppm) less than 0.75 less than 0.75 mMhomMho /cm for plugs /cm for plugs less than 1.0 less than 1.0 mMhomMho /cm for other /cm for other
greenhouse cropsgreenhouse crops less than 2.0 less than 2.0 mMhomMho /cm for other nursery /cm for other nursery
cropscrops
Managing High Salinity in Managing High Salinity in Water SupplyWater Supply
Managing High Salinity in Managing High Salinity in Water SupplyWater Supply
DiluteDilute with collected rainwater or with collected rainwater or other low salinity water sourcesother low salinity water sources
Use reverse osmosis water Use reverse osmosis water treatment, particularly for misting treatment, particularly for misting cuttings, irrigating seedlings, and cuttings, irrigating seedlings, and salt-sensitive cropssalt-sensitive crops
Where Does Where Does The Water The Water
Come From ?Come From ?
Soil ZoneSoil ZoneSand and Gravel Sand and Gravel
AquiferAquifer
Limestone or Limestone or Granite AquiferGranite Aquifer
Sandstone Sandstone AquiferAquifer
Examples of Variation in Groundwater Examples of Variation in Groundwater QualityQuality
Examples of Variation in Groundwater Examples of Variation in Groundwater QualityQuality
Well # 1 Well # 2 Well # 3
25
20
15
10
5
0
Fre
qu
ency
%
Irrigation Water Alkalinity concentrations Irrigation Water Alkalinity concentrations (ppm CaCO(ppm CaCO33) from Florida) from Florida
<40
40–8
0
80-2
0
120-
160
160-
200
200-
240
240-
280
280-
320
320-
360
360-
400
>40
0
Testing The Testing The Waters …Waters …
Testing Water Quality Testing Water Quality In-HouseIn-HouseTesting Water Quality Testing Water Quality In-HouseIn-House
Range 0-8 meq/L (0-400 ppm Range 0-8 meq/L (0-400 ppm alkalinity expressed as CaCOalkalinity expressed as CaCO33))
Accuracy Accuracy 0.4 meq/L or better 0.4 meq/L or better Kits from $30 for 100 tests toKits from $30 for 100 tests to
$155 for 100 tests. $155 for 100 tests.
Commercial Commercial LabLab
1.1. Need test for alkalinityNeed test for alkalinity2.2. Need Need Fluorine (F) and/or Chlorine Fluorine (F) and/or Chlorine
(Cl) if high levels are suspected.(Cl) if high levels are suspected.
Testing The Testing The Soil Solution !Soil Solution !
Simple technique for Simple technique for measuring pH and ECmeasuring pH and EC
Charts for recording pH & Charts for recording pH & ECEC
Guidelines for cropsGuidelines for crops
Procedures to keep on trackProcedures to keep on track
Measuring Measuring TechniqueTechnique
6 or 8-inch saucers are adequate for 6 or 8-inch saucers are adequate for collecting the leachatecollecting the leachate
Distilled Water Distilled Water VolumesVolumes
4 inch4 inch5 inch5 inch6 inch6 inch6.5 inch6.5 inch1 Qt1 Qt4 Qt4 Qt12 Qt12 Qt
757575757575
1001007575
150150350350
2.52.52.52.52.52.53.53.52.52.55.05.0
12.012.0
Pot SizePot Size mlml ozoz
Flats: Use 50 ml Distilled Flats: Use 50 ml Distilled WaterWater
EC EC ComparisonsComparisons
0 to 0.30 to 0.3
0.3 to 0.80.3 to 0.8
0.8 to 1.30.8 to 1.3
1.3 to 1.81.3 to 1.8
1.8 to 2.31.8 to 2.3
> 2.3> 2.3
1:21:2 SMESME PourThruPourThruIndicationIndication
0 to 0.80 to 0.8
0.8 to 2.00.8 to 2.0
2.0 to 3.52.0 to 3.5
3.5 to 5.03.5 to 5.0
5.0 to 6.05.0 to 6.0
> 6.0> 6.0
0 to 1.00 to 1.0
1.0 to 2.61.0 to 2.6
2.6 to 4.62.6 to 4.6
4.6 to 6.54.6 to 6.5
6.6 to 7.86.6 to 7.8
> 7.8> 7.8
Very LowVery Low
LowLow
NormalNormal
HighHigh
Very HighVery High
ExtremeExtreme
Monitoring Monitoring QuestionsQuestions
Number of samples?Number of samples?
How often?How often?
Options?Options?
How to How to MonitorMonitor
Sample plants with different Sample plants with different requirements separatelyrequirements separately
pH: acidic vs basicpH: acidic vs basic EC: high vs lowEC: high vs low
Randomly select plantsRandomly select plants
Select plants from interior Select plants from interior of benchof bench
Monitoring: the Monitoring: the Key ...Key ...
Have a manageable planHave a manageable plan
Consider monitor and Consider monitor and managing to be your insurance managing to be your insurance policypolicy
Initial Initial ECEC
0
0.5
1
1.5
2
2.5
3
1 2 3
Irrigations
DaysHours
Crop pH RangesCrop pH RangesFigure 2. Suggested substrate pH ranges for specific greenhouse crops grown in soilless substrate.
Species
pH Range4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 7.0
Easter Lily
CelosiaDianthusGeraniumMarigold, African
Hydrangea (Pink)
General CropsPansyPetuniaSalviaSnapdragonVincaHydrangea (Blue)
Azalea
4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 7.0
M&M KeyManagement Decision Range(take corrective steps so the pH moves back into theacceptable range)
Target Range
4.2
4.4
8.0
7.6
7.2
6.8
6.4
6.0
5.6
5.2
4.8
Week
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Crop _____________________________ Target pH Range _______
Starting Date (week 0) ________ Upper pH Decision Range_____
Ending Date ___________ Lower pH Decision Range_____
4.6
5.8
5.0
5.4
6.2
6.6
7.0
7.4
7.8
4.0
pH
Geraniums (6” pinched)
1/28
5/01
6.0 to 6.6
6.6 to 6.8
5.8 to 6.0
High pH Action High pH Action StepsSteps
Acidify water to pH of 5.8Acidify water to pH of 5.8
Switch from NOSwitch from NO33-- to NH to NH44
++
Apply an iron sulfate drenchApply an iron sulfate drench 3 lb per 100 gallons3 lb per 100 gallons
mist solution off of foliagemist solution off of foliage
Acidify water to pH of 5.1Acidify water to pH of 5.1
Low pH Action Low pH Action StepsSteps
Stop neutralizing alkalinity in waterStop neutralizing alkalinity in water
Switch from NHSwitch from NH44++ to NO to NO33
--
Apply flowable limestone products:Apply flowable limestone products:
start with 1 quart per 100 start with 1 quart per 100
gallonsgallons
mist solution off of foliagemist solution off of foliage
Monitoring Monitoring ECEC
Set target EC ranges for Set target EC ranges for crop being growncrop being grown
Account for growth stagesAccount for growth stages Establishment, active Establishment, active growth, and bloomgrowth, and bloom
Set upper and lower rangesSet upper and lower ranges
Plant Growth CyclePlant Growth Cycle
Poinsettia Growth Over Time
0
5
10
15
20
0 3 6 9 12 15
Weeks After Potting
Plan
t Dry
Wt (
g) Active GrowthActive GrowthEst
ab
lish
men
tEst
ab
lish
men
t
Matu
reM
atu
re
PourThru PourThru EC’sEC’s
Crops vary in requirementsCrops vary in requirements Low: 1.0 - 2.6 mS/cmLow: 1.0 - 2.6 mS/cm
begonia, cineraria, begonia, cineraria, impatiensimpatiens
Moderate: 2.0 - 3.5 mS/cmModerate: 2.0 - 3.5 mS/cm Easter lily, geranium, kaleEaster lily, geranium, kale
Heavy: 2.6 - 4.6 mS/cmHeavy: 2.6 - 4.6 mS/cm chrysanthemum, chrysanthemum, poinsettiapoinsettia
High EC Action High EC Action StepsSteps
Decrease fertilization rateDecrease fertilization rate
Decrease fertilization frequencyDecrease fertilization frequency
LeachLeach
Low EC Action Low EC Action StepsSteps
Increase fertilization rateIncrease fertilization rate
Increase fertilization Increase fertilization
frequencyfrequency
pH DriftpH Drift
Alkaline WaterAlkaline Water
pHpH
NHNH44++ fertilizers fertilizers
TimeTime
8.58.58.08.07.57.57.07.06.56.56.06.05.55.55.05.04.54.5
““Optimum” RangeOptimum” Range
Species Effect Species Effect on pHon pH
Marigold (African)Marigold (African)
pHpHStarting pHStarting pH
SpeciesSpecies
88
77
66
55
44
PansyPansy
VincaVincaZinniaZinnia
CelosiaCelosiaBegoniaBegonia
DianthusDianthusTomatoTomato
The Four Most The Four Most Common MistakesCommon Mistakes
1.1. Adoption of a single-fertilizer Adoption of a single-fertilizer formula for a given crop - formula for a given crop - Sticking to 20-20-20Sticking to 20-20-20
2.2. Trusting the fertilizer injectorTrusting the fertilizer injector
3.3. Not testing soil frequentlyNot testing soil frequently
4.4. Not testing the irrigation waterNot testing the irrigation water
5.5. Not performing foliar analysis Not performing foliar analysis mid-crop.mid-crop.
Pre-test irrigation water and media before Pre-test irrigation water and media before planting.planting.
Stock up on pH-adjusting chemicals and Stock up on pH-adjusting chemicals and basic fertilizers.basic fertilizers.
Use a water test analysis to select the Use a water test analysis to select the fertilizer and decide whether to acidify fertilizer and decide whether to acidify irrigation water.irrigation water.
Set up a pH, EC and nutrient monitoring Set up a pH, EC and nutrient monitoring program. program.
Testing The Testing The Foliage …Foliage …