Question on NPK

Murali+Chandra,

In the attachment you have posted, SSP is 0:8.8:0:11. So is the 8.8% P or P205??

8.8% P or 16% P2O5

Hi Agri_exec,

It says 8.8 % of P. So in a 100 Kg bag of it you have 8.8 kg of Phosphorus. I looks like it is commonly used as P, it may be a compound of P though.

Except Nitrogen which is inert, I doubt P & K exist in its native form like Nitrogen. So we need to assume N or P or K as a compound and its ratio as KG per 100 kg bag.

You can refer calculation A in the document.

Regards

Murali.

Murali,

I referred to the calculations. Again this is very misleading as traditionally all fertilizer companies sell it as a % of P.
Will post you more details soon.

Chandra,

Thanks again. If P2O5 is 16% then how is P 8.8%?

So in essence you are saying that in a fertilizer mix of 20:20:20 there is 20 N, 20 P (not p2o5) and 20K (not k2o) ?

Hi Agriexec,

You got it right. What ever be the compound of N or P or K, the numbers indicate only the unit of N or P or K, I think it has become a standard here.

Regards

Murali

Murali,

Thanks. So how is 16% P2O5 = P 8.8%?

Hi Agri Exec,

I think you are confused with compounds. Please find below. extract from attachment.

Units

Often a recommendation talks about units of a nutrient (eg phosphorus). A unit is the same as kilograms of that nutrient (eg 1 unit P is 1 kg P). But this is not the same as a kilogram of a fertiliser.

N:P:K:S

Fertilisers contain different amounts of nutrients, affecting the amount of the fertiliser you need. The nutrients are often written on the bag or packing slip as percentages, or as N:P:K:S (nitrogen:phosphorus:potassium:sulfur).

Example:
Single superphosphate is 0:8.8:0:11. This means that in 100 kg, there is 8.8 kg phosphorus, 11 kg sulfur. There is no nitrogen or potassium.

Starter 15 is 14:12.7:0:11. This means that in 100 kg, there is 14 kg nitrogen, 12.7 kg P, 11 kg sulfur and no potassium.
Calculating the amount of fertiliser required

This information can be used to calculate the amount of a fertiliser needed for a given amount of a nutrient:

Calculation A
Amount of fertiliser kg/ha = kg/ha nutrient ÷ % nutrient in fertiliser x 100.

Example: You need 20 units (kg) /ha of phosphorus (P) and you plan to use single superphosphate with 8.8% P.
Apply Calculation A

Amount of superphosphate required (kg/ha) = 20 kg/ha P÷ 8.8 P x 100 = 227 kg/ha

Dont worry about SSP or P2O5 etc or any other compound. If the bag says 0:8.8:20, and if the bag is 100 Kg to me what I get out of this 100 KG is only 8.8 KG of P I am not worried what compound this P is. and 20KG of K. Thats it period.

Then what is the balance 70.2 KG. Its “Bhoosa” here we call junk fillers. May be some neutral material. So in a bag of 100 KG if the bag says 0:8.8:20, we are only getting 28.8 KG of nutrients. (here it is P&K). Balance is Bhoosa.

Dont get bogged down by the compounds.

Similarly if the bag says 18:18:18, and if bag is 100kg, then I get 18KG of N, 18 KG of P and 18 KG of K. balance is bhoosa, junk fillers.

Regards

Murali

Murali,

Tumba dhanyavadagalu :slight_smile:. I really appreciate the trouble you take. I’ m not confused. I think i left you confused. Sorry for it though. I do understand some basics of this fertilizer thing. I know what a 20:20:10 (or for that matter of fact what other ratio means). My question to chandra was how is that 16% P2O5 = P 8.8%? Thats not it. There is more to it I’m sure.

Thanks

Hi Agri_Exec,

Never mind, I was also struggling with the compounds and its molecule structures etc etc.

But of all these compounds has any one found out what the plant likes ? That is in which form N,P or K will be tasty for it ?? ;D ;D

Both Idli and Dosa have the same combinations of Rice and Urad dhal, but we the eaters know there is a hell and heaven difference between the two. ;D ;D .

Even the same dough of idli , my wifey manages to make it rock solid, again and again, where as my mom with a flowery structure ;D Difference between Hell and Heaven :astonished: :astonished:

Regards

Murali

Here we Go…

Suppose we have a 100 kg bag 10:10:10 NPK fertilizer.

“N” represents the percentage weight of nitrogen. “P” is actually the weight of an equivalent quantity of P2O5 and not elemental phosphorus. Similarly “K” is actually the weight of an equivalent quantity of K2O, and not elemental potassium.

So the elemental Phosphorus and Potassium in the above mixture will be as below:

Phosphorus : 10x .43 = 4.3 Kgs
Potassium : 10 x .83 = 8.3 Kgs

(the weight of P2O5 is multiplied by 0.43 to compensate for the weight of the oxygen in the molecule, Similarly the weight of K2O can be multiplied by 0.83 to compensate for the weight of the oxygen in the molecule)

So unlike what we think, we wont really be getting 10 kgs each of NPK but will only be N =10 kgs, Phosphorus =4.3 Kgs and Potassium=8.3 Kgs. So you say a 10:10:10 mix is actually 10:4.3:8.3

By convention, the amounts (or analysis grade) of phosphorus and potassium in fertilizers are still expressed in this oxide form i.e P2O5 and K2O.

So if SSP is 16%, then elemental P is just 6.88. similarly in 0:8.8:0:11, you only have 3.784 P

Hope this helps.

For easy understanding, I have compiled some Typical specifications of Indian Fertilisers:

STRAIGHT NITROGENOUS FERTILISERS

Ammonium Sulphate

Moisture per cent by weight, maximum 1.0

Ammoniacal nitrogen per cent by weight, minimum 20.6

Free acidity (as H2SO4.) per cent by weight, maximum 0.025

Arsenic as (As2O3) per cent by weight, maximum 0.01

Sulphur (as S) ,per cent by weight, minimum 23.0

Urea (46% N) (While free flowing)

Moisture per cent by weight, maximum 1.0

Total nitrogen, per cent by weight, (on dry basis) minimum 46.00

Biuret per cent by weight, maximum 1.5

Urea (coated) (45% N) (While free flowing)

Moisture per cent by weight, maximum 0.5

Total nitrogen per cent by weight, content with coating, minimum 45.0

Biuret per cent by weight maximum 1.5

Ammonium Chloride

Moisture per cent by weight, maximum 2.0

Ammoniacal nitrogen per cent by weight, minimum 25.0

Chloride other than ammonium chloride (as NaCI) per cent by
weight, (on dry basis) maximum 2.0

Calcium Ammonium Nitrate (25 % N)

Moisture per cent by weight, maximum 1.00

Total ammoniacal and nitrate nitrogen per cent by weight, minimum 25.0

Ammoniacal nitrogen per cent by weight, minimum 12.5

Calcium nitrate per cent by weight, maximum 0.5

Calcium Ammonium Nitrate (26% N)

Moisture per cent by weight, maximum 1.00

Total ammoniacal and nitrate nitrogen per cent by weight, minimum 26.0

Ammoniacal nitrogen per cent by weight, minimum 13.0

Calcium nitrate per cent by weight, maximum 0.5

Anhydrous Ammonia

Ammonia per cent by weight, minimum 99.0

Water per cent by weight, maximum 1.0

Oil content by weight, maximum 20 ppm

Urea Super Granulated

Moisture, per cent by weight, maximum 1.00

Total nitrogen, per rent by weight (on dry basis), minimum 46.00

Biuret per cent by weight, maximum 1.5

Urea (Granular)

Moisture, per cent by weight, maximum 1.00

Total nitrogen, per rent by weight (on dry basis), minimum 46.00

Biuret per cent by weight, maximum 1.5

Urea Ammonium Nitrate (32%) (liquid)

Total Nitrogen, percent by weight, minimum 32.0

Urea Nitrogen, percent weight maximum 16.6

Ammonical Nitrogen, percent by weight, minimum 7.7

Nitrate Nitrogen, percent by weight, minimum 7.7

Specify gravity (at 150 C) 1.32

From ammonia (as NH3) percent by weight, minimum 0.10

STRAIGHT PHOSPHATIC FERTIUSERS

Single Superphosphate (16% P 205 Powdered)

Moisture per cent by weight, maximum 12.0

Free phosphoric acid (as P 205) per cent by weight, maximum 4.0

Water soluble phosphates (as P 205) per cent by weight, min 16.0

Sulphur (as S),percent by weight ,min. 11.0

Single Superphosphate (14% P 205 Powdered)

Moisture per cent by weight, maximum 12.0

Free phosphoric acid (as P 205) per cent by weight, maximum 4.0

Water soluble phosphates (as P 205) per cent by weight, min 14.0

Sulphur (as S),percent by weight ,min. 11.0

Triple Superphosphate

Moisture per cent by weight, maximum 12.0

Free phosphoric acid (as P 205) per cent by weight, maximum 3.0

Total phosphates (as p 205) per cent by weight, minimum 46.0

Water soluble phosphates (as P 205) per cent by weight, minimum 42.0

Single Superphosphate (16% P2O5 Granulated)

Moisture per cent by weight, maximum 5.0

Free phosphoric acid (as P 205.) per cent by weight, maximum 4.0

Water soluble phosphates (as P 205.) per cent by weight, minimum 16.0

Superphosphosphoric Acid (70%) P2O5 (liquid)

Total phosphate (asP2o5)percent by weight, minimum 70.0

Polyphosphate (asP2o5)percent by weight, minimum 18.9

Methanol Insoluble matter, percent weight, minimum 1.0

Magnesium) as Mg0), percent by weight, minimum 0.5

Specific gravity (at 24*c) 1.96

STRAIGHT POTASSIC FERTIlSERS

Potassium Chloride (Muriate of Potash)

Moisture per cent by weight, maximum 0.5

Water soluble potash content (as K20) per cent by weight, minimum 6O.0

Sodium as NaCI per cent by weight (on dry basis) maximum 3.5

Biuret, per cent by weight maximum 1.5

Potassium Sulphate

Moisture per cent by weight, maximum 1.5

Potash content (as K2O) per cent by weight, minimum 50.00

Total chlorides (as CI) per cent by weight, (on dry basis) maximum 2.5

Sodium as NaCI per cent by weight, (on dry basis) maximum 2.0

Sulphur (as S),percent by weight ,min. 17.5

Potassium Schoenite

Moisture per cent by weight, maximum 1.5

Potash content (as K2O) per cent by weight (on dry basis), minimum 23.00

Magnesium oxide (as MgO) per cent by weight, maximum 10.0

Sodium (as NaCI) (on dry basis) per cent by weight, maximum 1.5

Potassium Chloride (Muriate of Potash) (Granular)

Moisture per cent by weight, maximum 0.5

Water soluble potash (as K2O) per cent by weight, minimum 60.00

Sodium (as NaCI), per cent by weight, maximum 3.5

Magnesium (as MgCI2), per cent by weight, maximum 1.0

NP Complex fertilisers

Diammonium Phosphate (18-46-0)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 18.0

Ammoniacal nitrogen form per cent by weight, minimum 15.5

Total nitrogen in the form of urea per cent by weight, maximum 2.5

Neutral ammonium citrate soluble phosphates (as P 205)
per cent by weight, minimum 46.0

Water soluble phosphates (as P 206) per cent by weight, Min 41.0

Ammonium Phosphate Sulphate (16-20-0)

Moisture per cent by weight, maximum 1.0

Total ammoniacal nitrogen per cent by weight, minimum 16.0

Neutral ammonium citrate soluble phosphates (as P 205) %
by weight, minimum 20.0

Water soluble phosphates (as P 205) per cent by weight,minimum 19.5

Sulphur (as S),percent by weight ,min. 11.0

Ammonium Phosphate Sulphate (20-20-0)

Moisture per cent by weight, maximum 1.0

Total nitrogen per cent by weight, minimum 20.0

Ammoniacal nitrogen per cent by weight, minimum 18.0

Nitrogen in the form of urea per cent by weight, maximum 2.0

Neutral ammonium citrate soluble phosphates (as P 205)
per cent by weight, minimum 20.0

Water soluble phosphates (as P 205) per cent by weight, minimum 17.0

Sulphur (as S),percent by weight ,min. 13.0

Ammonium Phosphate Sulphate Nitrate (20-20-0)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 20.0

Ammoniacal nitrogen per cent by weight, minimum 17.0

Nitrate nitrogen per cent by weight, maximum 3.0

Neutral ammonium citrate soluble phosphates (as P 205)
per cent by weight, minimum 20.0

Water soluble phosphates (as P 205) per cent by weight, minimum 17.0

Sulphur (as S),percent by weight ,min. 13.0

Ammonium Phosphate Sulphate (18-9-0)

Moisture per cent by weight, maximum 1.0

Ammoniacal nitrogen per cent by weight, minimum 18.0

Neutral ammonium citrate soluble phosphates (as P 205) per cent
by weight, minimum 9.0

Water soluble phosphates (as P 205) per cent by weight, minimum 8.5

Nitro Phosphate (20-20-0)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 20.0

Nitrogen in ammoniacal form per cent by weight, minimum 10.0

Nitrogen in nitrate form per cent by weight, maximum 10.0

Neutral ammonium citrate soluble phosphates (as P 205)
per cent by weight, minimum 20.0

Water soluble phosphates (as P 205) per cent by weight, minimum 12.0

Calcium nitrate, per cent by weight, maximum 1.0

Urea Ammonium Phosphate (28-28-0)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 28.0

Ammoniacal nitrogen per cent by weight, minimum 9.0

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 28.0

Water soluble phosphates (as P 205) per rent by weight, minimum 25.2

Urea Ammonium Phosphate (24-24-0)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 24.0

Ammoniacal nitrogen per cent by weight, minimum 7.5

Nitrogen in the form of urea per cent by weight,maximum 16.5

Neutral ammonnium citrate soluble phosphates (as P 205)
per cent by weight, minimum 24.0

Water soluble phosphates (as P 205) per cent by weight, minimum 20.4

Urea Ammonium Phosphates (20-20-0)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 20.0

Ammoniacal nitrogen per cent by weight, minimum 6.4

Neutral ammonical citrate soluble phosphates (as P 205)
per cent by weight, minimum 20.0

Water soluble phosphates (as P 205) per cent by weight, minimum 17.0

Mono Ammonium Phosphate (11-52-0)

Moisture per cent by weight, maximum 1.0

Total nitrogen all in ammoniacal form per cent by weight,minimum 11.0

Neutral ammonium citrate soluble phosphates (as P 205)
per cent by weight, minimum 52.0

Water soluble phosphates (as P 205) per cent by weight, minimum 44.2

Nltrophosphate (23-23-0)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 23.0

Nitrogen in ammoniacal form per cent by weight, minimum 11.5

Nitrogen in nitrate form per cent by weight, maximum 11.5

Neutral ammonium citrate soluble phosphates (as P 205)
per cent by weight, minimum 23.0

Water soluble phosphates (as P 205) per cent by weight, minimum 18.5

Calcium nitrate, per cent by weight, maximum 1.0

Ammonium Nitrate Phosphate (23-23-0)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 23.0

Nitrogen in ammoniacal form per cent by weight,minimum 13.0

Nitrogen in nitrate form per cent by weight, maximum 10.0

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 23.0

Water soluble phosphates (as P 205) per cent by weight,minimum 20.5

Ammonium Poly-phosphate (10-34-0)(Liquid)

Total Nitrogen (all as Ammoniacal Nitrogen), percent by weight, Minimum 10.0

Total Phosphate (as P2O5) percent by weight minimum 34.0

Poly-phosphate) as P2O5) percent by weight minimum 22.1

Magenesium (as Mg0), percent by weight, minimum 0.5

Specific gravity (at 27oC) 11.4

N.P.K. COMPLEX FERTILISER

Nitrophosphate with Potash (15-15-15)

Moisture per cent by weight, maximum 1.5

Total nitrogen, minimum 15.0

Ammoniacal nitrogen per cent by weight, minimum 7.5

Nitrate nitrogen per cent by weight, maximum 7.5

Neutral ammonium citrate soluble phosphates
(as P 205) per cent by weight, minimum 15.0

water soluble phosphates (asP 205) per cent by weight, minimum 4.0

Water soluble potash (as K2O) per cent by weight minimum 15.0

Calcium nitrate, per cent by weight; maximum 1.0

N.P.K. (10-26-26)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 10.0

Ammoniacal nitrogen per cent by weight, minimum 7.0

Nitrogen in the form of urea per cent by weight, maximum 3.0

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 26.0

Water soluble potash (as K2O) per cent by weight, minimum 26.0

Water soluble phosphate (as P 205) per cent by weight,minimum 22.1

N.P.K. (12-32-16)

Moisture per cent by weight, maximum 1.0

Total nitrogen per cent by weight, minimum 12.0

Ammoniacal nitrogen per cent by weight, minimum 9.0

Nitrogen in the form of urea per cent by weight, maximum 3.0

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 32.0

Water soluble potash (as K2O) per cent by weight, minimum 27.2

Water soluble phosphate (as P 205) per cent by weight, minimum 16.0

N.P.K (22-22-11)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 22.0

Ammoniacal nitrogen per cent by weight, minimum 7.0

Urea nitrogen per cent by weight, maximum 15.0

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 22.0

Water soluble potash (as K2O) per cent by weight, minimum 11.0

Water soluble phosphate (as P 205) per cent by weight, minimum 18.7

N.P.K. (14-35-14)

Moisture per cent by weight, maximum 1.0

Nitrogen in ammoniacal form per cent by weight, minimum 14.0

Neutral ammonium citrate soluble phosphates (as P 205)
per cent by weight, minimum 35.0

Water soluble potash (as K2O) per cent by weight, minimum 14.0

Water soluble phosphate (as P 205) per cent by weight, minimum 29.7

N.P.K. (17-17-17)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 17.0

Ammoniacal nitrogen per cent by weight, minimum 5.0

Urea nitrogen per cent by weight, maximum 12.0

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 17.0

Water soluble potash (as K2O) per cent by weight, minimum 17.0

Water soluble phosphate (as P 205) per cent by weight, minimum 14.5

N.P.K. (14-28-14)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 14.0

Ammoniacal nitrogen per cent by weight, minimum 8.0

Urea nitrogen per cent by weight, maximum 6.0

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 28.0

Water soluble potash (as K2O) per cent by weight, minimum 14.0

Water soluble phosphate (as P 205) per cent by weight,minimum 23.8

N.P.K. (19-19-19)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 19.0

Ammoniacal nitrogen per cent by weight, minimum 5.6

Urea nitrogen per cent by weight, maximum 13.4

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 19.0

Water soluble potash (as K2O) per cent by weight, minimum 16.2

Water soluble phosphate (as P 205) per cent by weight, minimum 19.0

N.P.K. (17-17-17)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 17.0

Ammonium nitrogen per cent by weight, minimum 8.5

Nitrate nitrogen per cent by weight, maximum 8.5

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 17.0

Water soluble potash (as K2O) per cent by weight, minimum 17.0

Water soluble phosphate (as P 205) per cent by weight, minimum 19.0

N.P.K.(20-10—10)

Moisture per cent by weight, maximum 1.5

Total nitrogen per cent by weight, minimum 20.0

Urea nitrogen percent by weight, minimum 17.1

Ammonical nitrogen percent by weight, minimum 3.9

Neutral ammonium citrate soluble phosphate (as P 205)
per cent by weight, minimum 10.0

Water soluble potash (as K2O) per cent by weight, minimum 10.0

Water soluble phosphate (as P 205) per cent by weight, minimum 8.5

Hi Agri_Exec,

Wow, that’s a super duper research. Thanks a lot for that. So looking at those with high concentrations of N-P-K we can buy only those which is in excess of 20 %.

Since you have collected a lot, mind sharing some of the manufacturers. Mangalore Chemicals and Fertiliser is one from my side. IFFCO i think is another.

Now another question, a mega question arises, when to use what ?? If that key is found, Agri-exec, I think you have found a sure short cut to success ;D ;D

Regards

Murali

Murali,

Thanks. I will post on micro nutrients compositions when i have time. " When you use what"… Well, I will research on that when I have another “free friday”

the very NPK theory is obsolete. there is no point in this.

For the benefit of me and Argi_exec who has painstakingly complied this and for others can you elaborate on why ?

I think the whole Hydroponics is based on NPK theory. Or is it something to do with Organic Vs Inorganic debate.

Regards

Murali