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Organic Materials (321.84K)
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Organic Materials

Published May 2017

Animal manures and other sources of Phosphate, Potash, Magnesium and Sulphur

A guide to the total and available phosphate, potash and magnesium contents of some manures.

Typical phosphate, potash and magnesium contents in some animal and other organic manures. These can be used as default contents in the absence of actual measured or declared values.

DM Total nutrients  Available nutrients(1)
Phosphate
P2O5
Potash
K2O
Magnesium
MgO
Sulphur(2)
SO3
Phosphate
P2O5
Potash
K2O
Fresh FYM(3) %  kg/t  kg/t
Cattle 25 3.2 9.4 1.8 2.4 1.9 8.5
Pig 25 6.0 8.0 1.8 3.4 3.6 7.2
Slurries %  kg/m3  kg/m3
Cattle(4) 6 1.2 2.5 0.6 0.7 0.6 2.3
Pig(4) 4 1.5 2.2 0.7 0.7 0.8 2.0
Separated slurries (liquid) %  kg/m3  kg/m3
Strainer box (cattle) 1.5 0.3 1.5 ND ND 0.15 1.4
Weeping wall (cattle) 3 0.5 2.3 ND ND 0.25 2.1
Mechanical separator (cattle) 4 1.2 2.8 ND ND 0.6 2.5
Pig 3 1.1 2.0 ND ND 0.6 1.8
Separated slurries (solid) %  kg/t  kg/t
Cattle 20 2.0 3.3 ND ND 1.0 3.0
Pig 20 3.7 2.0 ND ND 1.9 1.8
Poultry manures %  kg/t  kg/t
20 8.0 8.5 2.7 3.0 4.8 7.7
40 12 15 4.3 5.6 7.2 14
60 17 21 5.9 8.2 10.2 19
80 21 27 7.5 11 12.6 24
Biosolids % kg/t kg/t
Digested cake 25 11 0.6 1.6 8.2 5.5 0.5
Thermally dried 95 55 2.0 6.0 23 28 1.8
Lime stabilised 25 7.0 0.7 2.4 7.4 3.5 0.4
Composted 40 10 3.0 2.0 6.1 5.0 2.7
Composts %  kg/t  kg/t
Green 60 3.0 6.8 3.4 3.4 1.5 5.4
Green/food 60 4.9 8.0 3.4 5.1 2.5 6.4
Wastes % kg/t or kg/m3 kg/t or kg/m3
Paper crumble
(chemically/physically treated)
40 0.4 0.2 1.4 0.6 ND ND
Paper crumble
(biologically treated)
30 3.8 0.4 1.0 2.4 ND ND
Mushroom compost 35 5.0 9.0 ND ND ND ND
Water treatment cake 25 3.4 0.4 0.8 5.5 ND ND
From food industry (general) 5 0.7 0.2 ND ND ND ND
Digestates – Whole % kg/t or kg/m3 kg/t or kg/m3
Food based 4.1 1.1 2.4 0.2 0.2 0.7 2.2
Crop based 5.5 1.7 4.4 0.6 0.6 1.0 4.0

(1)Nutrients available to the next crop (kg/tonne of product, not %).
(2)See below for sulphur availability.
(3)Potash values will be lower if FYM is stored in the open for long periods.
(4)Adjust nutrient contents if % DM is higher or lower.
DM = Dry matter.
ND = No data.
To convert kg/t to units/ton, multiply by 2.
To convert kg/m3 to units/1000 gallons, multiply by 9.

Sulphur availability from organic materials

Organic materials contain valuable amounts of crop-available sulphur and recent research has quantified sulphur supply from livestock manures and biosolids applications. Sulphur from autumn applications may be lost via overwinter leaching. The quantity leached will depend on soil type and overwinter rainfall and is likely to be higher on light textured soils in high rainfall areas.

Organic material % total SO3 available
Autumn applied %
Livestock manures 5-10
Biosolids 10-20
Spring applied  
Cattle FYM 15
Pig FYM 25
Poultry manure 60
Cattle/pig slurry 35
Biosolids 20

The importance of laboratory analysis and sampling

The nutrient content of organic manures on farms vary widely and so it is better to have a laboratory analysis carried out to get the correct values specifically for the farm and the year in question. However, it is important that the sample taken for analysis is truly representative. This means that sampling should be undertaken according to the protocol given in the AHDB Nutrient Management Guide (RB209), Section 2 Organic Manures.

In the absence of a recent analysis, and where thorough sampling can not be done, these typical values represent an alternative for nutrient planning purposes.