DEAS 904: 2023  
ICS 65.080  
 
© EAC 2023                                                                                                                        Second Edition 2023   
 DRAFT EAST AFRICAN STANDARD  
Fertilizers — Phosphate rock powder — Specification  
EAST AFRICAN COMMUNITY  DEAS 904: 2023  
ii © EAC  2023  – All rights reserved  
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© EAC 2023  – All rights reserved  iii 
 Foreword  
Development of the East African Stan dards has been necessitated by the need for harmonizing requirements 
governing quality of products and services in the East African Community. It is envisaged that through 
harmonized standardization, trade barriers that are encountered when goods and servi ces are exchanged 
within the Community will be removed.  
The Community has established an East African Standards Committee  (EASC)  mandated to develop and 
issue East African Standards  (EAS) . The Committee is composed of representatives of the National 
Stand ards Bodies in Partner States, together with the representatives from the public and private sector 
organizations  in the community .  
East African Standards are developed through  Technical Committees that are representative of key 
stakeholders including gov ernment, academia, consumer groups, private sector and other interested parties. 
Draft East African Standards are circulated to stakeholders through the National Standards Bodies in the 
Partner States. The comments received are discussed and incorporated b efore finalization of standards, in 
accordance with the Principles and procedures for develop ment of East African Standards . 
East African Standards are subject to review, to keep pace with technological advances. Users of the East 
African Standards are the refore expected to ensure that they always have the latest versions of the standards 
they are implementing .  
The committee responsible  for this document is Technical Committee EASC /TC 020, Agriculture and 
agrochemicals . 
 
 DRAFT EAST AFRICAN STANDARD  DEAS 904: 2023  
 
© EAC 2023  – All rights reserved  1 
 Fertilizers — Phosphate rock powd er — Specification  
1 Scope   
This draft East African Standard specifies requirements, sampling and test methods for phosphate rock 
fertilizers in powder form of biogenic sedimentary origin.  
2 Normative references   
The following documents are referred to in the text in such a way that some or all of their content constitutes 
requirements of this document.  For dated references, only the edition cited applies. For undated references, 
the latest edition of the referenced document (including any amendments) appli es. 
AOAC 965.08, Water (free) in fertilizers — Vacuum -desiccation  
AOAC 2006.03, Arsenic, Cadmium, Cobalt, Chromium, Lead, Molybdenum, Nickel and Selenium in fertilizers  
ISO 6598 , Fertilizer s — Determination of phosphorus content — Quinoline phosphomolybda te gravimetric 
method  
ISO 8157 , Fertilizer s, soil conditioners  and beneficial substances  — Vocabulary  
ISO 8397 , Solid fertilizers and soil conditioners — Test sieving  
ISO 15959,  Fertilizer s — Determination of extracted phosphorus  
ISO 17318 , Fertilizers an d soil conditioners — Determination of arsenic, cadmium, chromium, lead and 
mercury contents  
ISO 14820 -1, Fertilizers and liming materials - Sampling and sample preparation - Part 1: Sampling  
 ISO 148 20-2, Fertilizers and liming materials - Sampling and sa mple preparation - Part 2: Sample preparation  
ISO 7409, Fertilizers  -Marking - Presentation and declarations  
 
3 Terms and definitions   
For the purposes of this document, the terms and definitions given in ISO 8157  and the following apply.  
ISO and IEC maint ain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  
  
2 © EAC  2023  – All rights reserved  
 biogenic sedimentation  
deposition by settling of a suspended mat erial which may be either constituents, or secretions of plants or 
animals produced by life processes  
4 Requirements  
4.1 General requirements  
4.1.1  The fertilizer material shall consist of phosphate rock from natural deposits processed in the form of 
free-flowing powder. The colour of the phosphate rock powder fertilizer shall be uniform.  
4.1.2    The particle size shall be such that at least 90 % of the fertilizer materials pass through 0.15 -
mm sieve and the remaining material shall pass through 0.25 -mm s ieve. The fertilizer sample shall 
be determined by the method given in ISO 8397.4.2  Specific requirements  
Phosphate rock powder fertilizer shall comply with the requirements given  in Table 1  when tested in 
accordance with the test methods prescribed therei n. 
Table  1 — Specific r equirements for phosphate rock powder  fertilizer  
S/N Characteristic  Requirement  Test method  
i.  Total phosphates, (as P 2O5), % by mass, 
min. 28.0  ISO 6598   
ii.  Citric acid soluble phosphorus (as P 2O5) % 
by mass, min. 9 ISO 15959   
iii.  Calcium content (as CaO) % by mass, 
min. 35 Annex A  
iv.  Moisture, % by mass, max.  5 AOAC 965.08  
 
5 Contaminants  
5.1 Heavy metal contaminants in phosphate rock powder fertilizer  shall conform to the limits given in Table 
2 when tested in accordance with the test  methods prescribed therein . 
Table 2 — Requirements for heavy metal contaminants  in phosphate rock powder fertilizer   
S/N Heavy metal  Requirement  Test method  
i.  Arsenic , (As) mg/kg, max . 40  
ISO 17318  ii.  Cadmium , (Cd) mg/kg P2O5, 
max.  45  
iii.  Mercury , (Hg) mg/kg, max . 0.1 
iv.  Lead , (Pb) mg/kg, max.  30  
v.  Chromium , (Cr) mg/kg, max.  500 
vi.  Selenium , (Se) mg/kg , 
max.  1.0 AOAC 2006.03  
vii.  Nickel , mg/kg, max  120 AOAC 2006.03  
  
© EAC 2023  – All rights reserved  3 
  7 Packaging  
The fertilizer shall be packaged in materials that are clean and non -defecti ve that protect the product from 
physical, chemical and moisture contamination and withstand multiple stages of handling (transportation and 
storage).  
8 Labelling  
Each package shall be legibly and indelibly labeled in accordance with ISO 7409 in English an d/or any other 
official language in the destination country with the following information:  
a) name of the fertili zer; “phosphate rock powder”  
b)  brand name if any ; 
c) name and address of the manufacturer/packer ;  
d) net content by mass, in metric units ; 
e) nutrient con tent, that is  total phosphorus (% P 2O5) by mass  and citric acid soluble phosphorus (as 
P2O5) % by mass ; 
f) country of origin ; 
g) handling  instructions, including the words “ Use no hooks” ; 
h) production date   
i)  expiry date ;  
j) batch number ; and  
k) storage conditions . 
9 Sampling  
Sampling and sample preparation of phosphate rock powder  fertilizers shall be carried out as prescribed in 
ISO 14820 -1 and ISO 148 20-2 respectively . 
  
4 © EAC  2023  – All rights reserved  
 Annex  A 
(normative)  
 
Determination of calcium oxide  
A.1 Reagents  
For the purpose of this draft East African Standard, only analytical grade reagents and distilled water shall be 
used . 
 
A.1.1 Concentrated hydrochloric acid  
A.1.2  Concentrated nitric acid  
A.1.3  Hydrofluoric acid – 40 %  
A.1.4  Sodium carbonate , solid 
A.1.5  Dilute hydrochloric acid – 1:1 (v/v) 
A.1.6  Ammonium chloride , solid 
A.1.7  Dilute acetic acid  – 1:1 (v/v)  
A.1.8  Ammonium oxalate , solid 
A.1.9  Oxalic acid solution  – 1 g/L (m/v)  
A.1.10  Dilute sulphuric acid 1:4 (v/v)  
A.1.11  Standard potassium permanganate solution (0.1 N) – Dissolve 3.2 g of potassium permanganate 
in 1 L of water. Let stand in the dark overnight. Filter, without washing, through glass wool. Avoid contact with 
rubber or other organic material. Store in a dark -coloured glass -stoppered bottle. Standardized against 
standard sod ium oxalate.  
A.2 Procedure  
For cases where preparation of reagents should be needed; the following procedures should be followed:  
A.2.1  Transfer 0.5 g of sample that has been dried at 105 ºC to a 400 -mL tall from beaker. Dissolve, by 
boiling gently with 2 0 ml of concentrated hydrochloric acid and 10 ml of concentrated nitric acid, until the 
volume is reduced to about 10ml. Covering the beaker by watch -glass throughout the process of dissolution, 
add 20 ml of concentrated nitric acid and then evaporate to a  small volume. Wash the lower surface of the 
watch -glass into beaker with hot water, filter and wash collecting the filtrate and washings in a 250 -ml 
measuring or volumetric flask. Preserve the filter and washings.  
A.2.2  Dry the residue and burn off the fi lter paper by ignition in a platinum crucible. Moisten the cooled 
residue with a few drops of a concentrated nitric acid and add about 10 ml of hydrofluoric acid. Evaporate 
continuously just to dryness, ignite and fuse the residue with about 2 g to 3 g of sodium carbonate. Extract the 
melt in about 25 ml - 30 ml of dilute hydrochloric acid in a beaker, evaporate to dryness and bake. Extract the 
baked mass with about 10 ml of concentrated hydrochloric acid, dilute, filter and wash collecting the filtrate 
and washings in the same volumetric flask where in the first filtrate along with wa shings has been preserved 
under A.2 .1. Cool the combined  filtrates and make up to the mark.   
© EAC 2023  – All rights reserved  5 
 A.2.3  Pipette out exactly 100 ml from the solution in the volumetric flask under A.2.2 into a 400-ml beaker. 
Add sufficient ammonium chloride (about 15 ml) to hold magnesium in solution in presence of ammonium 
oxalate. Add 20 ml of dilute acetic acid, heat to boiling point and add about 2 g of ammonium oxalate while 
stirring. Boil and all ow the precipitate to settle for 1 h to 2 h, cool and filter the solution through a close filter 
paper. Wash the precipitate with hot water until free from oxalate.  
A.2.4  Dissolve the precipitate on the filter in about 50 ml of hot dilute hydrochloric aci d. Wash the filter 
thoroughly with hot water until the filter is free from acid and collect the washings also in the same beaker in 
which calcium was first precipitated. Reduce the bulk to about 100 ml by evaporation and re -precipitate 
calcium as oxalate u nder A.2.3 
A.2.5  Wash the precipitate of calcium oxalate into same beaker in which precipitation was first carried out 
and treat the filter with about 25 ml of warm (70 ºC to 80 ºC) dilute sulphuric acid for dissolving adhering 
precipitate of calcium oxala te. Wash the filter free from acid by means of hot water. Collect the washings also 
in the same beaker into which the precipitate was transferred. Add about 25 ml more of dilute sulphuric acid 
and raise the temperature of contents to about 70 ºC. When the precipitate has dissolved, titrate with standard 
potassium permanganate solution until a permanent pale pink colour persists in solution.  
A.3 Calculation  
The calcium oxide content, expressed as percent by mass, shall be calculated as follows:  
=
CFBA 100 (0.028)   
where  
A is the volume, in millilitres, of  standard potassium permanganate solution;  
B is the normality of the standard potassium permanganate solution;  
C is the mass, in grams , of the sample represented by the aliquot taken;  and 
F is the dilut ion factor . 
 
. DEAS 904: 2023    
 
© EAC 2023  – All rights reserved