plant fertilizer calculation videos 4

See Fertilizer Chemistry

Example Fertilizer Calculation N, P2o5, K20

Maxibloom Fertilizer Label

bove is an example of a nutrient labels guaranteed analysis.
It tells us how much of each element is in the bag at percentage weight by volume (%w/v).
This provides us with enough information to establish a reasonably accurate ppm.

Note that analyzing the ppm from fertilizer labels won’t provide 100% accurate ppms.
Fertilizers sold worldwide are often only required to be listed accurately to within 0.4%.

Regulations around the world require that NPK.. values be presented somewhat ambiguously.
Therefore, listings for the same nutrient may appear to vary on a country-by-country basis.
For example, when looking at our labels guaranteed analysis you will find note that it states;

Available Phosphate (P2O5)……….15.0%
Available Potash (K2O)…………..14.0%

This information becomes important when interpreting the guaranteed analysis.

That is, it is important to note that the P and K numbers found on the guaranteed analysis do not always reflect the actual amounts of elemental phosphorous and potassium by %.

With our label, this is the case and P is listed as P2O5 (phosphorous pentoxide) and K is listed as K2O (potassium oxide) percentage.

When phosphorus is listed as P2O5 it is only 43% elemental P and when potassium is listed as K2O it is only 83% elemental K.

Therefore, when this system is in use, a 5-15-14 NPK ratio truly reflects elemental NPK 5-6.45-11.62.

N = 5
P = 15 * 0.43 = 6.45
K = 14 * 0.83 = 11.62

Additionally, other nutrients such as calcium (Ca), magnesium (Mg) and sulfur (S) can be listed in their oxide form (CaO, MgO, SO3) or in elemental form, or both.
To convert other nutrient listings that may appear on some labels use these equations.

CaO to Ca multiply by 0.714
MgO to Mg multiply by 0.6031
SO3 to S multiply by 0.4

Percentage Weight by Volume (%w/v)

A simple way of understanding how to convert a %w/v listing found on the guaranteed analysis into grams per litre is by understanding that 1ml of RO water weighs 1gram.

Percentage weight by volume %w/v refers to the total weight of elements contained within a finished concentrate of a given total volume.

For example, 5% of nitrogen added to 1 litre(1000ml) of RO water would mean that there is 50grams of N in the water.

1000 (ml) * 0.05 (5% nitrogen) = 50 (grams of N)

Converting %w/v to ppm and ppm to %w/v

To establish ppm from %w/v you simply need to multiply by 10000.
5% (nitrogen) * 10000 = 50000 (ppm)
To establish %w/v from ppm you simply need to divide by 10000.
50000 (ppm) / 10000 = 5% (nitrogen)

To establish the concentration of individual elements in the water, the guaranteed analysis (%w/v) should first be converted into ppm, then multiplied by the usage rate (per litre), then divided by 1000 (ml).

For example, if a nutrient lists 5% nitrogen, when it is used at 5grams per 4 litres it will yield 62.5 ppm of nitrogen per litre.

Step 1 : 5% (nitrogen) * 10000 = 50000 (ppm)
Step 2 : 5grams / 4L = 1.25g/litre
Step 3 : (50000 (ppm) * 1.25g/litre) / 1000ml (1 litre) = 62.5ppm of nitrogen per litre (1000ml)

Doing the math

Using what we’ve learned, we’re finally ready to find the ppm of our fertilizer.

5 * 10000 = 50k nitrogen ppm
6.45 * 10000 = 64.5k phosphorus ppm
11.62 * 10000 = 116.2k potassium
5 * 10000 = 50k calcium ppm
3.5 * 10000 = 35k magnesium ppm
4 * 10000 = 40k sulfur ppm
0.1 * 10000 = 1k iron ppm

50k + 64.5k + 116.2k + 50k + 35k + 40k + 1k = 356,7k or 356700 ppm.
(356700ppm * 1.25g/litre) / 1000ml = 445ppm(~0.9EC) per litre.

How Much Phosphorus and Potassium are Really in Your Fertilizer?

Fertilizer Calculations for Greenhouse Crops

Understanding phosphorus fertilizers

Common Fertilizers Table

Table 1: Percentages of water-soluble and available phosphate in several common fertilizer source

P2O5 sourceNTotalAvailableP2O5Water soluble* P2O5
Superphosphate (OSP)0%21%20%85%
Concentrated Superphosphate (CSP)0%45%45%85%
Monoammonium Phosphate (MAP)11%49%48%82%
Diammonium Phosphate (DAP)18%47%46%90%
Ammonium Polyphosphate (APP)10%34%34%100%
Rock Phosphate0%34%38%0%
*Water-soluble data are a percent of the total P2O5.
Source: Ohio Cooperative Extension Service.

More Fertilizer Calculation Examples with Videos

Fertilizer calculation one
% weight15515
desired ppm =  mg/L or mg/kghoal
( 1 liter oof water weighs 1 kg)200mg/L
0.15 mg of N per mg og Fertilizer
 200 / 0.15 =
mg N / L   /   mg N/ mg F = 
 mg F / L ) for desired 200 ppm)
 divide by 1000 to get grans
1.333333333 g per L
for 2000 L solution2000
2666.666667grams F in 2000 L1000
2.666666667kh of F in 2000 L
Fertilizer calculation two
1 gallon = 3.7854 L
5000gallon holding tank
* 3.79
     18,950.00Liters storage tank
Calcium Nitrate0.155
15.5 % Nmh N per Mg Ca Bitrate
desired ppm 100 )mg/L)0.64516129grams
     12,225.81times storage tank


Fertilizer calculation one
Fertilizer calculation two
Fertilizer calculation three
Fertilizer calculation four
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Other Nutrients


Common nameChemical name (Formula)
Potash fertilizerc.1942 potassium carbonate (K2CO3); c.1950 any one or more of potassium chloride (KCl), potassium sulfate (K2SO4) or potassium nitrate (KNO3).[9][10] Does not contain potassium oxide (K2O), which plants do not take up.[11] However, the amount of potassium is often reported as K2O equivalent (that is, how much it would be if in K2O form), to allow apples-to-apples comparison between different fertilizers using different types of potash.
Nitrate of potash or saltpeterpotassium nitrate (KNO3)
Sulfate of potash (SOP)potassium sulfate (K2SO4)
Permanganate of potashpotassium permanganate (KMnO4)

Potassium oxide (K2O) is an ionic compound of potassium and oxygen. The chemical formula K2O (or simply ‘K’) is used in several industrial contexts: the N-P-K numbers for fertilizers,


Phosphorus pentoxide is a chemical compound with molecular formula P4O10 (with its common name derived from its empirical formula, P2O5).

The phosphate or orthophosphate ion [PO 4]3− is derived from phosphoric acid by the removal of three protons H+


Agricultural lime, also called aglime, agricultural limestone, garden lime or liming, is a soil additive made from pulverized limestone or chalk. The primary active component is calcium carbonate.. Calcium oxide (CaO), is commonly known as quicklim.e

Calcareous (/kælˈkɛəriəs/) is an adjective meaning “mostly or partly composed of calcium carbonate“, in other words, containing lime or being chalky.

Calcium carbonate shares the typical properties of other carbonates. Notably it

CaCO3(s) + 2 H+(aq) → Ca2+(aq) + CO2(g) + H2O(l)

Calcium carbonate reacts with water that is saturated with carbon dioxide to form the soluble calcium bicarbonate.

CaCO3(s) + CO2(g) + H2O(l) → Ca(HCO3)2(aq)

Agriculture and aquaculture

Agricultural lime, powdered chalk or limestone, is used as a cheap method for neutralising acidic soil, making it suitable for planting, also used in aquaculture industry for pH regulation of pond soil before initiating culture.[54]


Ammonia is a compound of nitrogen and hydrogen with the formula NH3.

The ammonium cation is a positively charged polyatomic ion with the chemical formula NH+ 4. It is formed by the protonation of ammonia (NH3).

Urea, also known as carbamide, is an organic compound with chemical formula CO(NH2)2.

soil reactions

Fertilizer Chemistry

Agricultural Salts

Ammonium Nitrate –  NH4NO3.3400000
Ammonium Phosphate(NH4)3PO4.or ADP-MAP (NH4)(H2PO4).12610000
Ammonium Sulfate – (NH4)2SO421000024
Calcium Nitrate – Ca(NO3)2 or CaN2O615001900
Magnesium Nitrate – Mg(NO3)2(1100090
Magnesium Sulfate – MgSO 4,00001013
Potassium NitrateKNO 3.13046000
Urea – CO(NH2)2. carbamide4600000
Ammonium Ion

Lewis Dot Structure for the Ammonium Ion

Nitrate Ion

Nitrate Ion Lewis Structure: How to Draw the Lewis Structure for Nitrate Ion

How to Draw the Lewis Dot Structure for NH4NO3: Ammonium nitrate

How to Write the Formula for Ammonium nitrate

PO4 3- Lewis Structure: How to Draw the Lewis Structure for PO4 3-

ammonium nitrate
phosphate ion

How to Write the Formula for Ammonium phosphate

How to draw the (NH4)3PO4 Lewis Dot Structure (Ammonium Phosphate)

How to Draw the Lewis Structure for the Sulfate Ion

How to Write the Formula for Ammonium sulfate

sulfate anion so4 -2

How to draw the (NH4)2SO4 Lewis Dot Structure (Ammonium Sulfate)

ammonium sulfate

How to Draw the Lewis Dot Structure for Mg(NO3)2 : Magnesium nitrate

How to Draw the Lewis Dot Structure for KNO3 (Potassium Nitrate)

How to Draw the Lewis Dot Structure for CH4N2O / CO(NH2)2 : Urea

urea lewis structure



Salts- In chemistry, a salt is a chemical compound consisting of an ionic assembly of cations and anions.[1] Salts are composed of related numbers of cations (positively charged ions) and anions (negatively charged ions) so that the product is electrically neutral (without a net charge). Often a salt is an ionic compound in which the cation is a metal and anion is a nonmetal or group of nonmetals.

An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H+ cation and the anion of the acid.[1]

Element groupElement (central atom)Oxidation stateAcid formulaAcid name[8][9]Anion formulaAnion name
7Manganese+7HMnO 4Permanganic acidMnO4Permanganate
+6H 2MnO 4Manganic acidMnO2− 4Manganate
8Iron+6H2FeO4Ferric acidFeO42–Ferrate
13Boron+3H 3BO 3Boric acid (formerly orthoboric acid)[10]BO3− 3Borate (formerly orthoborate)
14Carbon+4H 2CO 3Carbonic acidCO2−3Carbonate
Silicon+4H 4SiO 4Silicic acid (formerly orthosilicic acid)[10]SiO4−4Silicate (formerly orthosilicate)
14, 15Carbon, nitrogen+4, −3HOCNCyanic acidOCNCyanate
15Nitrogen+5HNO 3Nitric acidNO3Nitrate
+3HNO 2Nitrous acidNO2Nitrite
Phosphorus+5H 3PO 4Phosphoric acid (formerly orthophosphoric acid)[10]PO3−4Phosphate (orthophosphate)
H 3PO 5Peroxomonophosphoric acidPO3−3Peroxomonophosphate
+5, +3(HO) 2POPO(OH) 2Diphosphoric(III,V) acidO 2POPOO2− 2Diphosphate(III,V)
16Sulfur+6H 2SO 4Sulfuric acidSO2− 4Sulfate
H 2S 2O 7Disulfuric acidS 2O2− 7Disulfate
17Chlorine+7HClO 4Perchloric acidClO 4Perchlorate
+5HClO 3Chloric acidClO 3Chlorate

Hydroxyl Group Definition

A hydroxyl group is a functional group that attaches to some molecules containing an oxygen and hydrogen atom, bonded together. Also spelled hydroxy, this functional group provides important functions to both alcohols and carboxylic acids. Alcohols are chains of carbon molecules with a functional hydroxyl group side chain. The electronegativity of the oxygen adds a slight polarity to alcohols, which is why they are able to interact with other polar molecules such as water and some solutes. Below is a general alcohol which contains a hydroxyl group. The oxygen is the red atom, while the hydrogen is represented by the grey atom. The R represent any generic carbon chain.

Carboxylic acids contain a hydroxyl group within their functional carboxyl group. A carboxyl group consists of a carbonyl group bonded to a hydroxyl group. A carbonyl group is simply a carbon double bonded to an oxygen. These two functional groups together create an extremely reactive molecule, which is prone to forming new carbon-carbon bonds. Along with alcohols, carboxylic acids are commonly seen in nature. A generic carboxylic acid with its hydroxyl group can be seen below.

Besides these two large classes of molecules that are functionally dependent on the hydroxyl group, many other molecules contain hydroxyl groups. As mentioned, a large part of the action caused by the hydroxyl group is due to the electronegativity of the oxygen. Because oxygen has a stronger attraction with the electrons bonding hydrogen to the molecule, the hydroxyl group can easily lose the hydrogen to an atom that will share electrons more equally. When this happens, the oxygen takes on a much more negative electrical energy, and can donate the extra electrons it has to a number of reactions. Biological organisms use this property of oxygen to help connect and disconnect chains of carbon molecules, which hold energy the organism can use to power cellular functions.

Related Biology Terms

Carboxyl group – A carbon doubled bonded to an oxygen and also bonded to a hydroxyl group.

Carbonyl group – A carbon double bonded to an oxygen and any other molecules, including more carbons.

Electronegativity – The attraction that an atom has for electrons, compared to the other types of atoms that it shares electrons with in covalent bonds.

Polarity – The property of a molecule that arises from the stable differentiation of electrical poles across a molecule or part of a molecule.

Nitric Acid- HNO3

Ammonium nitrate is the ammonium salt of nitric acid. It has a role as a fertilizer, an explosive and an oxidising agent. It is an inorganic molecular entity, an ammonium salt and an inorganic nitrate salt.

Phosphoric acid, H3PO4 or H3O4P ,  is a phosphorus oxoacid that consists of one oxo and three hydroxy groups joined covalently to a central phosphorus atom. It has a role as a solvent, a human metabolite, an algal metabolite and a fertilizer. It is a conjugate acid of a dihydrogenphosphate and a phosphate ion.

Ammonium dihydrogen phosphate is the ammonium salt of phosphoric acid (molar ratio 1:1). It has a role as a fertilizer. It contains a dihydrogenphosphate.

Sulfuric acid, H2SO4 or H2O4S ,  is a sulfur oxoacid that consists of two oxo and two hydroxy groups joined covalently to a central sulfur atom. It has a role as a catalyst. It is a conjugate acid of a hydrogensulfate

Ammonium sulfate, (NH4)2SO4,  is an inorganic sulfate salt obtained by reaction of sulfuric acid with two equivalents of ammonia. A high-melting (decomposes above 280℃) white solid which is very soluble in water

Calcium nitrate,  is inorganic nitrate salt of calcium. It has a role as a fertilizer. It is an inorganic nitrate salt and a calcium salt. It contains a calcium(2+).

            NO3 Nitrate is a nitrogen oxoanion formed by loss of a proton from nitric acid.

Magnesium sulfate is a magnesium salt having sulfate as the counterion.. It is a magnesium salt and a metal sulfate.

Potassium nitrate is the inorganic nitrate salt of potassium. It has a role as a fertilizer. It is a potassium salt and an inorganic nitrate salt.

Urea is a carbonyl group with two C-bound amine groups. It has a role as a flour treatment agent, a human metabolite, a Daphnia magna metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite, a mouse metabolite and a fertilizer. It is a monocarboxylic acid amide and a one-carbon compound. It derives from a carbonic acid. It is a tautomer of a carbamimidic acid.

Al2(SO4)3.  Aluminum Sulfate Anhydrous is an aluminum salt

Agricultural lime, CaCO3. ,also called aglime, agricultural limestone, garden lime or liming, is a soil additive made from pulverized limestone or chalk. The primary active component is calcium carbonate.


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