Fertilizer

Background Information

Fertilizer units

Plants need 3 macronutrients (N,P,K), 3 secondary macronutrients(Ca, Mg, S), and many micronutrients(Mn, Fe, etc).

Fertilizer labels report the mass percentage of (N:P:K) or (Nitrogen:Phosphorus:Potassium). For example 10 grams of 10:10:10 fertilizer yields 1 gram of Nitrogen.

Dissolve that 1 gram of Nitrogen in 1 liter of water and you will get 1,000 ppm (parts per million).

Sidenotes

NPK quirk

Unfortunately calculations for P and K differ slightly. P and K were historically calculated with ash molecules P2O5 and K2O.

Elemental P in P2O5 = 44%

Elemental K in K2O = 83%

So 10 grams of a 10:10:10 fertilizer provides 1 gram of Nitrogen, 0.44 grams of Phosphorus, and 0.83 grams of Potassium.

Remaining elements Ca, Mg, S, and micronutrients (Mn, Fe, etc) are calculated the same as Nitrogen.

What a Plant Can Use

Nutrients must come in the form of ions.

Certain forms of fertilizer take time to break down. Nitrogen fertilizer often comes bound in the form Urea. Urea is digested by bacteria but the bacteria has to die before the ammonium ions will be released.

Certain forms of ions become toxic and aren't preferred. Ammonium ions can be used by plants but become toxic at lower concentrations than nitrate ions (50ppm vs 250ppm).

Water-soluble fertilizers such as Calcium Nitrate are immediately available.

Water-soluble fertilizers with sodium should not be used since sodium can become toxic at low concentrations (50ppm).

Fertilizer levels

Exact concentrations are not necessary. Plants will take what they need. But too much of a single element will lockout other nutrients or cause toxicity.

Sample fertilizer with Ammonium

N: 45 ppm

P: 26 ppm

K: 27 ppm

Ca: 13 ppm

Mg: 3 ppm

S: 4 ppm

Mn: 0.7 ppm

Fe: 0.35 ppm

Sample fertilizer with Nitrates

N: 92 ppm

P: 35 ppm

K: 120 ppm

Ca: 66 ppm

Mg: 7 ppm

S: 13 ppm

Mn: 0.65 ppm

Fe: 1.3 ppm

Sample fertilizer for flowers

N: 158 ppm

P: 93 ppm

K: 219 ppm

Ca: 132 ppm

Mg: 7 ppm

S: 40 ppm

Mn: 1 ppm

Fe: 2 ppm

Elemental composition of pine needles.

N: 12,000 ppm

P: 1,100 ppm

K: 4,500 ppm

Ca: 3,100 ppm

Mg: 700 ppm

S: 1,300 ppm

Mn: 500 ppm

Fe: 50 ppm

Pine nutrient deficiency symptoms

N,P: stunted growth.

K: needle discoloration grayish-green. Older needles become purple or brown. New growth has dieback.

Ca: resin secretion, changes in morphology: short, fat, and curled growth.

Mg: needle discoloration: brown tip, a yellow middle, and a dark green base. Commonly caused by calcium buildup binding the magnesium fertilizer.

S: abnormal (summertime) chlorosis

Calculator

Method

Preset: Fertilizer-grade Calcium Nitrate = Ca5(NO3)10NH4NO3(H2O)10

Preset: Potassium Nitrate = KNO3

Preset: Epson salt/ Magnesium Sulfate = MgSO4(H2O)7

Preset: Monopotassium Phosphate = KH2PO4

Preset: Potassium Sulfate = K2SO4

Preset: Diammonium Phosphate = (NH4)2HPO4

Fertilizer calculator also accepts new chemical formulas.

Notes

This tool uses a genetic algorithm to create an approximate solution.

There may not exist an exact mixture that solves input ppm requests. Answers may vary between runs.

By selecting more fertilizer options, the algorithm can get closer to the requested goal.

References

Inspiration

Background Information

Nutrient requirements

Colorado State University. 2014. "Plant Nutrition", CMG GardenNotes 231

http://www.cmg.colostate.edu/GardenNotesUpdate.shtml

Colorado State University. 2014. "Understanding Fertilizers", CMG GardenNotes 232

http://www.cmg.colostate.edu/GardenNotesUpdate.shtml

Plant Elements by Part

Joanna Skonieczna, Stanisław Małek, Krzysztof Polowy, Andrzej Węgiel (2014). "Element Content of Scots Pine (Pinus Sylvestris L.) Stands of Different Densities", Drewno 2014, Vol. 57, No. 192

Clemens Reimanna, Friedrich Koller b,, Bjørn Frengstadc,Galina Kashulinad, Heikki Niskavaarae, Peter Englmaier (2000). "Comparison of the element composition in several plant species and their substrate from a 1 500 000-km2 area in Northern Europe"

Nitrate vs Ammonium

http://www.kno3.org/product-features-a-benefits/nitrate-no3-versus-ammonium-nh4

Kathryn S. Hahne and Ursula K. Schuch (2004). "Response of Nitrate and Ammonium on Growth of Prosopis Velutina and Simmondsia Chinensis Seedlings". University of Arizona College of Agriculture 2004 Turfgrass and Ornamental Research Report

Nutrient deficiency

A. L. MCCOMB (April,1943). "Mycorrhizae and Phosphorus Nutrition of Pine Seedlings in a Prairie Soil Nursery"

Edward I. Sucoff (1961). "Potassium, Magnesium, and Calcium Deficiency Symptoms of Loblolly and Virginia Pine Seedlings"

E. S. LYLE;N. D. PEARCE (1960)."Sulfur Deficiency in Nursery Seedlings May Be Caused By Concentrated Fertilizers"

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