Fertilizer Formula 2 - eGRO Electronic Grower … 2& Understanding a Fertilizer Bag • P is an...
Transcript of Fertilizer Formula 2 - eGRO Electronic Grower … 2& Understanding a Fertilizer Bag • P is an...
3/20/13&
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Brian Whipker
How Fertilizer Formula Influences Plant Growth
N"
Fer&lity"Rate"
P" K"
What"key"nutri&onal"factors"
influence"plant"growth?"
Understanding a Fertilizer Bag
Acidic"or"
basic?"
Nitrogen"
form?"
Mixing?"
EC"check"
values?"
Contains"P,"
Ca,"Mg,"micros?"
Fer&lizer"
sources?"
Understanding Nitrogen
Type%
Bag%%%NO3-N%
Bag%%%NH4-N%
Bag%%%
Urea%
Total%%%NO3-
N%
Total%%%NH4-N%+%Urea% Total%%%
NH4-N%Total%%%Urea%
20-20-20% 6.11$ 3.89$ 10.0$ 30.5%$ 69.5%$ 19.5%$ 50.0%$
20-10-20% 12.06$ 7.94$ 0.0$ 60.3%$ 39.7%$ 39.7%$ 0.0%$
15-5-15% 11.75$ 1.20$ 2.05$ 78.3%$ 21.7%$ 8.0%$ 13.6%$
13-2-13% 11.9$ 0.3$ 0.8$ 91.6%$ 8.4%$ 2.3%$ 6.1%$
Nitrogen"Form&
Prefer">80%"as"Nitrate"N"
NH4NN+Urea"boost"growth"
Avoid"excess"NH4NN+Urea"with"cold"temperatures"
• Description: Yellowing (chlorosis) – Use of only
NH4-N based fertilizers (20-20-20)
– Plants grown cold (50F nights)
Leaves&–&En/re&Plant&
Ammonium&nitrogen&toxicity&
Ini&al"• Description:
Yellowing (chlorosis) – Use of only
NH4-N based fertilizers (20-20-20)
– Plants grown cold (50F nights)
Leaves&–&En/re&Plant&
Advanced"
Ammonium&nitrogen&toxicity&
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Understanding a Fertilizer Bag
• P is an essential element – Target 5 to 10 ppm in substrate – P is the primary contributor to plant stretch
Is"Phosphorus"(P)"provided?"
Understanding Phosphorus
Phosphate"vs."Compactness"P2O5&as&a&%&of&N&in&postCplant&fer/lizer&
P2O5&=&50%&of&N& 15%& 7.5%& 0%&(e.g.&20C10C20)& (13C2C13)&
Source:"Paul"Nelson,"NCSU"
Phosphorus Deficiency: Lower Leaf Purpling
Brian"W
hipker"
Phosphorus Deficiency: Lower Leaf Spots
Brian"W
hipker"
Brian"W
hipker"
NP"
NP"
NP"
P"Deficiency:"Leaf"spo[ng/yellowing"Gerbera%growth%as%fertilization%rate%increases%
(in%ppm%N)%
&50""""""""""""75"""""""""""100"""""""""""200""""""""""""300""""""""400&
K. Yeon Jeong, B. Whipker, I. McCall, and J. Frantz!
Brian"W
hipker"
Understanding&Fer/lizer&Rates&
3/20/13&
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• Description: Lower leaves with total leaf yellowing
Nitrogen&Deficiency&
Nitrogen"Deficiency"
Understanding a Fertilizer Bag
• Need Ca and Mg – Irrigation water, dolomite lime, or fertilizer
• Micros – Supply minimal package unless water
source contains excessive levels
Ca,"Mg,"&"micros"provided?"
Magnesium Deficiency Lower leaf interveinal chlorosis
Brian"W
hipker"
Understanding a Fertilizer Bag
Acidic"or"basic?"
Understanding a Fertilizer Bag Other"Informa&on"
Understanding a Fertilizer Bag
Mixing"and"Target"EC"
200""""""""""""""""""""2.0""""""""13.5""""""17.3"""""""27.0""""""40.5""""""""""""""""1.24"
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Know the critical element concentrations and
interactions? • Generally N supplied at 100 to 300 ppm • Ratio of N to K20 usually 1:1 • Low P is preferred • Check for Ca, Mg, S, and micros
– Note Cal-Mg formulas use Magnesium Nitrate because of solubility, thus S may not be supplied.
– Epsom salts (Magnesium sulfate) is an excellent source of Mg and S (1#/100 gal water, if water tests confirm the need)
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