# The Fertilisers Regulations 1991, COMPOUND FERTILISERS

Extent: E+W+S

Group
Name of Material
Meaning
Declarations
Limits of variation (absolute value in percnetage by weight, except where otherwise specified)
(1)
(2)
(3)
(4)
(5)
(6)
*As determined by the Petermann method.
*This is only an indication of how the material should be named and accordingly this form of words should not be used in the statutory statement.
1
NPK fertiliser
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5);
3 Not less than 5% potassium oxide (K2O).
The sum of the three nutrients must be not less than 20% by weight. The product must not contain basic slag, Thomas phosphate, Thomas slag, calcined phosphate, aluminium-calcium phosphate, soft ground rock phosphate, or partially solubilised rock phosphate.
The P2O5 content soluble only in mineral acids must not exceed 2%.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Where phosphorus pentoxide soluble in water is less than 2%, amount of:–
1 Phosphorus pentoxide soluble in neutral ammonium citrate
Where phosphorus pentoxide soluble in water is equal to or greater than 2%, amount of:
1 Phosphorus pentoxide soluble in neutral ammonium citrate and in water
P2O5 1.1
P2O5 0.5
2 Phosphorus pentoxide soluble in water
As set out in paragraph 7(a) of this Schedule
Potassium oxide (K2O)
Amount of potassium oxide soluble in water
K2O 1.1
N 1.9
+P2O5 1.9
+K2O 1.9
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
Cl 0.2
NPK fertiliser containing aluminium-calcium phosphate
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nigrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5) of which at least 2% must be soluble in water, and at least 5% soluble in mineral acids; and
3 Not less than 5% potassium oxide (K2O).
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
The sum of the three nutrients must be not less than 20% by weight. At least 75% of the declared phosphorus pentoxide soluble in mineral acids must be soluble in alkaline ammonium citrate (Joule). The product must not contain basic slag, Thomas Phosphate, Thomas slag, calcined phosphate, soft ground rock phosphate or partially solubilised rock phosphate, and not less than 90% of the aluminium-calcium phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
P2O5 1.1
P2O5 0.5
Amount of phosphorus pentoxide soluble in water
As set out in paragraph 7(a) of this Schedule
Amount of phosphorus pentoxide soluble in mineral acids (after deduction of the amount of phosphorus pentoxide soluble in water)
As set out in paragraph 7(a) of this Schedule
Amount of phosphorus pentoxide soluble in alkaline ammonium citrate
As set out in paragraph 7(a) of this Schedule
Potassium Oxide (K2O)
K2 1.1
K2O 0.5
Amount of potassium oxide soluble in water
N 1.9
+P2O5 1.9
+K2O 1.9
Optional declarations
Amount of chlorine
Cl 0.2
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
NPK fertiliser containing soft ground rock phosphate
NPK fertiliser containing partially solubilised rock phosphate
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nigrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5) of which at least 2% should be soluble only in mineral acids, at least 5% soluble in neutral ammonium citrate and in water and at least 2.5% soluble in water;
3 Not less than 5% potassium oxide (K2O).
The sum of the three nutrients must be not less than 20% by weight. Neither product must contain basic slag, Thomas phosphate, Thomas slag, calcined phosphate or aluminium-calcium phosphate. Not less than 90% of the soft ground rock phosphate should be able to pass through a sieve with a mesh of 0.063 mm, and not less than 90% of the partially solubilised rock phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
P2O5 1.1
P2O5 0.5
Amount of phosphorus pentoxide soluble in water
Amount of phosphorus pentoxide soluble in neutral ammonium citrate and in water
As set out in paragraph 7(a) of this Schedule
Amount of phosphorus pentoxide soluble only in mineral acids
As set out in paragraph 7(a) of this Schedule
K2O 0.5
Potassium Oxide (K2O)
Amount of potassium oxide soluble in water
K2O 1.1
N 1.9
+p2O5 1.9
+K2O 1.9
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
Cl 0.2
NPK fertiliser (Phosphate ingredient, aluminium-calcium phosphate only)
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5);
3 Not less than 5% potassium oxide (K2O)
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
The sum of the three nutrients must be not less than 20% by weight. At least 75% of the declared phsophorus pentoxide soluble in mineral acids must be soluble in alkaline ammonium citrate (Joule). The product must not contain any phosphate material other than aluminium-calcium phosphate and not less than 90% of the aluminium-calcium phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
P2O5 1.1
P2O5 0.5
Amount of phosphorus pentoxide soluble in alkaline ammonium citrate
As set out in paragraph 7(a) of this Schedule
Potassium Oxide (K2O)
Amount of potassium oxide soluble in water
K2O 1.1
N 1.9
+P2O5 1.9
+K2O 1.9
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
Cl 0.2
NPK fertiliser (Phosphate ingredient, calcined phosphate only)
Product obtained chemically or by blending, without addition of organic nutrient of animal or vegatable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less t;han 5% phosphorus pentoxide (P2O5);
3 Not less than 5% potassium oxide (K2O).
The sum of the three nutrients must be not less than 20% by weight. The product must not contain any phposphate material other than calcined phosphate. Not less than 75% of the calcined phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in alkaline ammonium citrate
P2O5 1.1
P2O5 0.5
Potassium Oxide (K2O)
Amount of potassium oxide soluble in water
K2O 1.1
N 1.9
+P2 1.9
+K2O 1.9
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine may be made”.
Cl 0.2
NPK fertiliser (Phosphate ingredient, soft ground rock phosphate only)
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:—
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5);
3 Not less than 5% potassium oxide (K2O).
The sum of the three nutrients must be not less than 20% by weight. At least 55% of the declared phosphorus pentoxide soluble in mineral acids must be soluble in 2% formic acid. The product must not contain any phosphate material other than soft ground rock phosphate. Not less than 90% of the soft ground rock phosphate should be able to pass through a sieve with a mesh of 0.063 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
P2O5 1.1
P2O5 0.5
Amount of phosphorus pentoxide soluble in 2% formic acid
As set out in parabraph 7(a) of this Schedule
Potassium Oxide (K2O)
Amount of potassium oxide soluble in water
K2O 1.1
N 1.9
+P2 1.9
+K2O 1.9
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine may be made”.
Cl 0.2
NPK fertiliser (Phosphate ingredient: basic slag only)
NPK fertiliser (Phosphate ingredient; Thomas phosphate only)
NPK fertiliser (Phosphate ingredient; Thomas slag only)
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5);
3 Not less than 5% potassium oxide (K2O).
The sum of the three nutrients must be not less than 20% by weight. The product must not contain any phosphate material other than basic slag, Thomas phosphate or Thomas slag.
Not less than 75:% of the basic slag, Thomas phosphate or Thomas slag should be able to pass through a sieve with a mesh of 0.160 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in 2% citric acid
P2O5 1.1
P2O5 0.5
Potassium Oxide (K2O)
Amount of potassium oxide soluble in water
K2O 1.1
N 1.9
+P2 1.9
+K2O 1.9
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine may be made”.
Cl 0.2
NPK fertilisers containing crotonylidene diurea or isobutylidene diurea or urea formaldehyde (as appropriate)
Product obtained chemically without addition of organic nutrients of animal or vegetable origin and containing crotonylidene diurea or isobutylidene diurea or urea formaldehyde.
Containing by weight:
1 not less than 5% nitrogen (N)
2 not less than 5% phosphorus pentoxide (P2O5)
3 not less than 5% potassium oxide (K2O).
The sum of the three nutrients must not be less than 20%.
At least 25% of the declared content of total nitrogen must derive from crotonylidene diurea, or isobutylidene diurea or urea formaldehyde.
At least 60% of the declared nitrogen content from urea formaldehyde must be soluble in hot water.
The product must not contain Thomas slag, calcined phosphate, aluminium-calcium phosphate, partially solubilised natural phosphate or natural phosphate.
The P2O5 content soluble only in mineral acids must not exceed 2%
Nitrogen (N)
Amount of:—
total nitrogen;
amount where equal to or greater than 1% by weight of:
1 nitric nitrogen
2 ammoniacal nitrogen
3 ureic nitrogen;
nitrogen, where appropriate, from
1 crotonylidene diurea or
2 isobutylidene diurea or
3 urea formaldehyde;
nitrogen from urea formaldehyde that is only soluble in hot water;
nitrogen from urea formaldehyde that is soluble in cold water
Phosphorus Pentoxide (P2O5)
Where phosphorus pentoxide soluble in water is less than 2%, amount of:—
1 Phosphorus pentoxide soluble in neutral ammonium citrate
Where phosphorus pentoxide soluble in water is equal to or greater than 2%, amount of:—
1 Phosphorus pentoxide soluble in neutral ammonium citrate and in water
2 Phosphorus pentoxide soluble in water
Potassium oxide (K2O)
Amount of potassium soluble in water
Optional declarations
Amount of chlorine.
Where the chlorine content is not greater than 2% the statement ‘low in chlorine’ may be made
2
NP fertiliser
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5).
The sum of the two nutrients must be not less than 18% by weight. The product must not contain basic slag. Thomas phosphate, Thomas slag, calcined phosphate, aluminium-calcium phosphate, soft ground rock phosphate or partially solubilised rock phosphate.
The P2O5 content soluble only in mineral acids must not exceed 2%.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Where phosphorus pentixide soluble in water is less than 2%, amount of:–
1 Phosphorus pentoxide soluble in neutral ammonium citrate.
Where phosphorus pentoxide soluble in water is equal to or greater than 2%, amount of–
1 Phosphorus pentoxide soluble in neutral ammonium citrate and in water
P2O5 1.1
P2O5 0.5
2 Phosphorus pentoxide soluble in water
As set out in paragraph 7(a) of this Schedule
N 1.5
+P2O5 1.5
NP fertiliser containing aluminium-calcium phosphate
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5) of which at least 2% must be soluble in water, and at least 5% soluble in mineral acids.
The sum of the two nutrients must be not less than 18% by weight. At least 75% of the declared phosphorus pentoxide soluble in mineral acids must be soluble in alkaline ammonium citrate (Joule). The product must not contain basic slag, Thomas phosphate, Thomas slag, calcined phosphate, soft ground rock phosphate or partially solubilised rock phosphate, and not less than 90% of the aluminium-calcium phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
P2O5 1.1
P2O5 0.5
Amount of phosphorus pentoxide soluble in water
Amount of phosphorus pentoxide soluble in mineral acids (after deduction of the amount of phosphorus pentoxide soluble in water)
Amount of phosphorus pentoxide soluble in alkaline ammonium citrate
As set out in paragraph 7(a) of this Schedule
N 1.5
+P2O5 1.5
NP fertiliser containing soft ground rock phosphate
NP fertiliser containing partially solubilised rock phosphate
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5) of which at least 2% should be soluble only in mineral acids, at least 5% soluble in neutral ammonium citrate and in water and at least 2.5% soluble in water.
The sum of the two nutrients must be not less than 18% by weight. Neither product must contain basic slag, Thomas phosphate, Thomas slag, calcined phosphate or aluminium-calcium phosphate. Not less than 90% of the soft ground rock phosphate should be able to pass through a sieve with a mesh of 0.063 mm, and not less than 90% of the partially solubilised rock phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
P2O5 1.1
P2O5 0.5
Amount of phosphorus pentoxide soluble in water
Amount of phosphorus pentoxide soluble in neutral ammonium citrate and in water
Amount of phosphorus pentoxide soluble only in mineral acids
As set out in paragraph 7(a) of this schedule
N 1.5
+P2O5 1.5
NP fertiliser (Phosphate ingredient: aluminium-calcium phosphate only)
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5).
The sum of the two nutrients must be not less than 18% by weight. At least 75% of the declared phosphorus pentoxide soluble in mineral acids must be soluble in alkaline ammonium citrate (Joule). The product must not contain any phosphate material other than aluminium-calcium phosphate and not less than 90% of the aluminium-calcium phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
P2O5 1.1
P2O5 0.5
Amount of phosphorus pentoxide soluble in alkaline ammonium citrate
As set out in paragraph 7(a) of this schedule
N 1.5
+P2O5 1.5
NP fertiliser (Phosphate ingredient: calcined phosphate only)
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5).
The sum of the two nutrients must be not less than 18% by weight. The product must not contain any phosphate material other than calcined phosphate. Not less than 75% of the calcined phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in alkaline ammonium citrate
P2O5 1.1
N 1.5
+P2O5 1.5
P2O5 0.5
NP fertiliser (Phosphate ingredient: soft ground rock phosphate only)
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5).
The sum of the two nutrients must be not less than 18% by weight. At least 55% of the declared phosphorus pentoxide soluble in mineral acids must be soluble in 2% formic acid. The product must not contain anyh phosphate material other than soft ground rock phosphate. Not less than 90% of the soft ground rock phosphate should be able to pass through a sieve with a mesh of 0.063 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
P2O5 1.1
P2O5 0.5
Amount of phosphorus pentoxide soluble in 2% formic acid
As set out in paragraph 7(a) of this schedule
N 1.5
+P2O5 1.5
NP fertiliser (Phosphate ingredient basic slag only)
NP fertiliser (Phosphorus ingredient: Thomas phosphate only)
NP fertiliser (Phosphate ingredient; Thomas slag only)
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% phosphorus pentoxide (P2O5).
The sum of the two nutrients must be not less than 18% by weight. The product must not contain any phosphate material other than basic slag, Thomas phosphate or Thomas slag. Not less than 75% of the basic slag, Thomas phosphate or Thomas slag should be able to pass through a sieve with a mesh of 0.160 mm.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in 2% citric acid
P2O5 1.1
N 1.5
+P2O5 1.5
P2O5 0.5
NP fertilisers containing crotonylidene diurea or isobutylidene diurea or urea formaldehyde (as appropriate)
Product obtained chemically without addition of organic nutrients of animal or vegetable origin and containing crotonylidene diurea or isobutylidene diurea or urea formaldehyde.
Containing by weight:—
1 not less than 5% nitrogen (N)
2 not less than 5% phosphorus pentoxide (P2O5)
The sum of the two nutrients must be not less than 18% by weight.
At least 25% of the declared content of total nitrogen must derive from crotonylidene diurea,, or isobutylidene diurea or urea formaldehyde.
At least 60% of the declared nitrogen content from urea formaldehyde must be soluble in hot water.
The product must not contain Thomas slag, calcined phosphate, aluminium-calcium phosphate, partially solubilised natural phosphate or natural phosphate.
The P2O5 content soluble only in mineral acids must not exceed 2%
Amount of—
total nitrogen;
amount where equal to or greater than 1% by weight of:—
1 nitric nitrogen
2 ammoniacal nitrogen
3 ureic nitrogen;
nitrogen, where appropriate, from
1 crotonylidene diurea or
2 isobutylidene diurea or
3 urea formaldehyde;
nitrogen from urea formaldehyde that is soluble only in hot water;
nitrogen from urea formaldehyde that is soluble in cold water
Phosphorus Pentoxide (P2O5)
Where phosphorus pentoxide soluble in water is less than 2%, amount of:—
1 Phosphorus pentoxide soluble in neutral ammonium citrate
Where phosphorus pentoxide soluble in water is equal to or greater than 2% amount of:—
1 Phosphorus pentoxide soluble in neutral ammonium citrate and in water
2 Phosphorus pentoxide soluble in water
3
NK fertiliser
Product obtained chemically or by blending, without addition of organic nutrients of animal or vegetable origin, containing by weight:–
1 Not less than 3% nitrogen (N);
2 Not less than 5% potassium oxide (K2O).
The sum of the two nutrients must be not less than 18% by weight.
Nitrogen (N)
...
Fertiliser
. . .
Amount of total nitrogen
. . .
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
N 1.1
As set out in paragraph 7 of this Schedule
N 0.5
. . .
Potassium Oxide (K2O)
Amount of potassium oxide soluble in water
K2O 1.1
N 1.5
+K2O 1.5
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
Cl 0.2
NK fertilisers containing crotonylidene diurea or isobutylidene diurea or urea formaldehyde (as appropriate)
Product obtained chemically without addition of organic nutrients of animal or vegetable origin and containing crotonylidene diurea or isobutylidene diurea or urea formaldehyde.
Containing by weight:—
1 not less than 5% nitrogen (N)
2 not less than 5% potassium oxide (K2O)
The sum of the two nutrients must be not less than 18% by weight.
At least 25% of the declared content of total nitrogen must derive from crotonylidene diurea, or isobutylidene diurea or urea formaldehyde.
At least 60% of the declared nitrogen content from urea formaldehyde must be soluble in hot water
Nitrogen (N)
Amount of:—
total nitrogen;
amount where equal to or greater than 1% weight of:—
1 nitric nitrogen
2 ammoniacal nitrogen
3 ureic nitrogen;
nitrogen, where appropriate, from
1 crotonylidene diurea or
2 isobutylidene diurea or
3 urea formaldehyde;
nitrogen from urea formaldehyde that is soluble only in hot water;
nitrogen from urea formaldehyde this is soluble in cold water.
Potassium Oxide (K22O)
Potassium oxide soluble in water. The indication ‘low in chlorine’ is linked to a maximum content of 2% chlorine (Cl). Chlorine content may be declared
4
PK fertiliser
Product obtained chemically or by blending, without addition of organic nutrient of animal or vegetable origin, containing by weight:–
1 Not less than 5% phosphorus pentoxide (P2O5)
2 Not less than 5% potassium oxide (K2O)
The sum of the two nutrients must be not less than 18% by weight. The product must not contain basic slag, Thomas phosphate, Thomas slag, calcined phosphate, aluminium-calcium phosphate, soft ground rock phosphate, or partially solubilised rock phosphate.
The P2O5 content soluble only in mineral acids must not exceed 2%.
Phosphorus Pentoxide (P2O5)
Where phosphorus pentoxide soluble in water is less than 2%, amount of:–
1 Phosphorus pentoxide soluble in neutral ammonium citrate
Where phosphorus pentoxide soluble in water is equal to or greater than 2%, amount of:–
1 Phosphorus pentoxide soluble in neutral ammonium citrate and in water
P2O5 1.1
P2O5 0.5
2 Phosphorus pentoxide soluble in water
As set out in paragraph 7(a) of this Schedule
Potassium Oxide(K2O)
Amount of potassium oxide soluble in water
K2O 1.1
P2O5 1.5
+K2O 1.5
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
Cl 0.2
PK fertiliser containing aluminium calcium phosphate
Product obtained chemically or by blending, without addition of organic nutrient of animal or vegetable origin, containing by weight:–
1 Not less than 5% phosphorus pentoxide (P2O5) of which at least 2% must be soluble in water, and at least 5% soluble in mineral acids;
2 Not less than 5% potassium oxide (K2O)
The sum of the two nutrients must be not less than 18% by weight. At least 75% of the declared phosphorus pentoxide soluble in mineral acids must be soluble in alkaline ammonium citrate (Joule). The product must not contain basic slag, Thomas phosphate, Thomas slag, calcined phosphate, soft ground rock phosphate, or partially solubilised rock phosphate, and not less than 90% of the aluminium-calcium phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
Amount of phosphorus pentoxide soluble in water
Amount of phosphorus pentoxide soluble in mineral acids (after deduction of the amount of phosphorus pentoxide soluble in water)
Amount of phosphorus pentoxide soluble in alkaline ammonium citrate
P2O5 1.1
As set out in paragraph 7(a) of this Schedule
P2O5 0.5
Potassium Oxide(K2O)
Amount of potassium oxide soluble in water
K2O 1.1
P2O5 1.5
+K2O 1.5
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
Cl 0.2
PK fertiliser containing soft ground rock phosphate
Product obtained chemically or by blending, without addition of organic nutrient of animal or vegetable origin, containing by weight:–
1 Not less than 5% phosphorus pentoxide (P2O5) of which at least 2% whould be soluble only in mineral acids, at least 5% soluble in neutral ammonium citrate and in water and at least 2.5% soluble in water.
2 Not less than 5% potassium oxide (K2O)
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
Amount of phosphorus pentoxide soluble in water
Amount of phosphorus pentoxide soluble in neutral ammonium citrate and in water
Amount of phosphorus pentoxide soluble only in mineral acids
P2O5 1.1
As set out in paragraph 7(a) of this Schedule
P2O5 0.5
PK fertiliser containing partially sulubilised rock phosphate
The sum of the two nutrients must be not less than 18% by weight. Neither product must contain basic slag, Thomas phosphate, Thomas slag, calcined phosphate or aluminium-calcium phosphate. Not less than 90% of the soft ground rock phosphate should be able to pass through a sieve with a mesh of 0.063 mm, and not less than 90% of the partially solubilised rock phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Potassium Oxide(K2O)
Amount of potassium oxide soluble in water
K2O 1.1
P2O5 1.5
+K2O 1.5
K2O 0.5
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
Cl 0.2
PK fertiliser (Phosphate ingredient; aluminium-calcium phosphate only)
Product obtained chemically or by blending, without addition of organic nutrient of animal or vegetable origin, containing by weight:–
1 Not less than 5% phosphorus pentoxide (P2O5)
2 Not less than 5% potassium oxide (K2O)
The sum of the two nutrients must be not less than 18% by weight. At least 75% of the declared phosphorus pentoxide soluble in mineral acids must be soluble in alkaline ammonium citrate (Joule). The product must not contain any phosphate material other than aluminium-calcium phosphate and not less than 90% of the aluminium-calcium phosphate should be able to pass through a sieve with a mesh of 0.160 mm.
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
Amount of phosphorus pentoxide soluble in alkaline ammonium citate
Potassium Oxide(K2O)
Amount of potassium oxide soluble in water
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
P2O5 1.1
As set out in paragraph 7(a) of this Schedule
K2O 1.1
P2O5 1.5
+K2O 1.5
Cl 0.2
P2O5 0.5
K2O 0.5
PK fertiliser (Phosphate ingredient; calcined phosphate only)
Product obtained chemically or by blending, without addition of organic nutrient of animal or vegetable origin, containing by weight:–
1 Not less than 5% phosphorus pentoxide (P2O5)
2 Not less than 5% potassium oxide (K2O)
The sum of the two nutrients must be not less than 18% by weight. The product must not contain any phosphate material other than calcined phosphate. Not less than 75% of the calcined phosphate should be able to pass through a sieve with a mesh or 0.160 mm.
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in alkaline ammonium citrate
Potassium Oxide(K2O)
Amount of potassium oxide soluble in water
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
P2O5 1.1
K2O 1.1
P2O5 1.5
+K2O 1.5
Cl 0.2
P2O5 0.5
K2O 0.5
PK fertiliser (Phosphate ingredient: soft ground rock phosphate only)
Product obtained chemically or by blending, without addition of organic nutrient of animal or vegetable origin, containing by weight:–
1 Not less than 5% phosphorus pentoxide (P2O5)
2 Not less than 5% potassium oxide (K2O)
The sum of the two nutrients must be not less than 18% by weight. At least 55% of the declared phosphorus pentoxide soluble in mineral acids must be soluble in 2% formic acid. The product must not contain any phosphate material other than soft ground rock phosphate. Not less than 90% of the soft ground rock phosphate should be able to pass through a sieve with a mesh of 0.063 mm.
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in mineral acids
Amount of phosphorus pentoxide soluble in 2% formic acid
Potassium Oxide(K2O)
Amount of potassium oxide soluble in water
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
P2O5 1.1
As set out in paragraph 7(a) of this Schedule
K2O 1.1
P2O5 1.5
+K2O 1.5
Cl 0.2
P2O5 0.5
K2O 0.5
PK fertiliser (Phosphate ingredient: basic slag only)
PK fertiliser (Phosphate ingredient: Thomas phosphate only)
PK fertiliser (Phosphate ingredient: Thomas slag only)
Product obtained chemically or by blending, without addition of organic nutrient of animal or vegetable origin, containing by weight:–
1 Not less than 5% phosphorus pentoxide (P2O5)
2 Not less than 5% potassium oxide (K2O)
The sum of the two nutrients must be not less than 18% by weight. The product must not contain any phosphate material other than basic slag, Thomas phosphate or Thomas slag. Not less than 75% of the basic slag, Thomas phosphate or Thomas slag should be able to pass through a sieve with a mesh of 0.160 mm.
Phosphorus Pentoxide (P2O5)
Amount of phosphorus pentoxide soluble in 2% citric acid
Potassium Oxide(K2O)
Amount of potassium oxide soluble in water
Optional declarations
Amount of chlorine
Where the chlorine content is not greater than 2% the statement “low in chlorine” may be made
P2O5 1.1
K2O 1.1
P2O5 1.5
+K2O 1.5
Cl 0.2
P2O5 0.5
K2O 0.5
5
Compound fertiliser
Product not otherwise specified in this Section of this table, obtained by mixing or blending materials to provide either two or three of the major nutrients nitrogen (N), phosphorus pentoxide (P2O5) and potassium oxide (K2O). Excluded are any materials sold or offered for sale for improving soil structure or as growing media, which contain less than 1% each of these nutrients.
At least one of the nutrients must be derived from a material mentioned in the second column of Section A of this table.
Nitrogen(N)
Amount of nitrogen
Amount of ureic nitrogen save that a declaration of 10% or less need not be made
Phosporus Pentoxide (P2O5)
Amount of total phosphorus pentoxide
Amount of phosphorus pentoxide soluble in water
N. 0.5 (for declarations below 3.5% N)
1.1 (for declarations 3.5% N and above)
As set out in paragraph 7(b) of this Schedule
P2O5 (for declarations below 5,.5% P2P5)
1.1 (for declarations 5,5% P2O5 and above)
As set out in paragraph 7(a) of this Schedule
6
Compound fertilisers not containing any material mentioned in the second column of Section A of this table
Products not otherwise specified in this Section of this table, including those products obtained by mixing or blending materials to provide either two or three of the major nutrients nitrogen (N), phosphorus pentoxide (P2O5) and potassium oxide (K2O). Excluded are any materials sold or offered for sale for improving soil structure or as growing media, which contain less than 1% each of these nutrients. None of the nutrients must be derived from a material mentioned in the second column of Section A of this table.
Potassium Oxide (K2O)
Amount of total potassium oxide
K2 (for declarations bewlo 5.5% K2O)
1.1 (for declarations 5.5% K2O and above)
N+P2O5 1.5 for products containing two nutrients only
N+K2O 1.5 for products containing two nutrients only
P2O5+K2O 1.5 for products containing two nutrients only
N 1.9
+P2O5 1.9
+K2O 1.9

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Source: https://www.legislation.gov.uk/uksi/1991/2197/schedule/1/crossheading/compound-fertilisers (the official version)
Page: https://openlegislation.uk/fertilisers-regulations-1991/schedule-1/crossheading-compound-fertilisers
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.