PUBLIC REVIEW DRAFT DRAFT UGANDA STANDARD  
  DUS DEAS 905 
First  Edition  
2018-mm-dd 
 
 Reference number  
DUS DEAS 905: 2018 
© UNBS 201 8 
  
Fertilizer — Granulated phosphate rock ― Specification  
 PUBLIC REVIEW DRAFTDUS DEAS 905:2018 
ii                © UNBS  2018 - All rights reserved 
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct application  
© UNBS 2018 
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permission from UNBS. 
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Uganda 
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 PUBLIC REVIEW DRAFTDUS DEAS 905:2018 
© UNBS  2018 - All rights reserved                iii National foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade, Industry and 
Cooperatives established under Cap 327, of the Laws of Uganda, as amended.  UNBS is mandated to co-
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT Agreement of the World Trade Organisation (WTO). 
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of representatives of 
consumers, traders, academicians, manufacturers, government and other stakeholders. 
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
This Draft Uganda Standard, DUS DEAS 905: 2018, Fertilizer — Granulated phosphate rock ― Specification,  
isidentical with and has been reproduced from a Draft East African Standard, DEAS 905:2018, Fertilizer — 
Granulated phosphate rock ― Specification,  and is being proposed for adoption as a Uganda Standard. 
This standard was developed by the Food and agriculture  Standards Te chnical Committee (UNBS/TC 2). 
Wherever the words, “ East African Standard" appear, they should be replaced by "Uganda Standard." 
 
  PUBLIC REVIEW DRAFT DEAS 905:2018  
 
© EAS 2018                                                                                                               First Edition 201 8 
 
 
DRAFT EAST AFRICAN STANDARD  
 
Fertilizer  ― Granulated phosphate rock ― Specification  
 
EAST AFRICAN COMMUNITY  PUBLIC REVIEW DRAFTDEAS 905:2018  
© EAC 2018 – All rights reserved  Foreword  
Development of the East African Standards has been necessitated by the need for 
harmonizing requirements governing quality of products a nd services in the East African 
Community. It is envisaged that through harmonized standardization, trade barriers that are 
encountered when goods and services are exchanged within the Community will be removed.  
In order to achieve this objective, the Com munity established an East African Standards 
Committee mandated to develop and issue East African Standards.   
The Committee is composed of representatives of the National Standards Bodies in Partner 
States, together with the representatives from the privat e sectors and consumer 
organizations. Draft East African Standards are circulated to stakeholders through the 
National Standards Bodies in the Partner States. The comments received are discussed and 
incorporated before finalization of standards, in accorda nce with the procedures of the 
Community.  
East African Standards are subject to review, to keep pace with technological advances. 
Users of the East African Standards are therefore expected to ensure that they always have 
the latest versions of the standard s they are implementing .  PUBLIC REVIEW DRAFTDEAS 905:2018  
  Fertilizer  ― Granulated phosphate rock ― Specification  
1 Scope  
This Draft East African  Standard specifies  requir ements, methods of sampling and test for 
granulated phosphate rock fertilizers. The fertilizer shall contain phosphor us as the only 
predominant primary plant nutrient of biogenic sedimentary origin.  
2 Normative Reference  
The following referenced standards are indispensable for the application of this standard. For 
dated references, only the edition cited applies. For un dated references, the latest edition of 
the referenced standard (including any amendments) applies:  
ISO 8157 , Fertilizer  and Soil Conditioners ― Vocabulary  
DEAS 913 , Fertilizer  – Methods of sampling   
ISO 17318 Fertilizers and soil conditioners ― Determination of arsenic, cadmium, chromium, 
lead and mercury contents  
ISO 8397 Solid fertilizers and soil conditioners ― Test sieving  
3 Terms and defini tions  
For the purpose of this East African  standard, the following terms and definition shall apply 
together with those given in ISO 8157  
3.1 
biogenic sedimentation  
biogenic sedimentation – is the deposition by settling of a suspended material which may be  
either constituents, or secretions of plants or animals produced by life processes . 
4 Requirements  
4.1 General requirements  
4.1.1  Physical  
The fertilizer material shall be in the form of free -flowing granules made from naturally 
occurring phosphate rock p owder. The colour of the fertilizer material shall be uniform.  
4.1.2  The particle size  
The fertilizer shall be free flowing and shall be in a suitably granular form. It shall be free from 
lumps and foreign matter. When tested by ISO 8397  granule size of th e phosphate rock 
fertilizer material shall be such that at least 90 % by mass is of size range of 1 mm to 4 mm. 
Not more than 10 % by mass shall be of granule size range of 1 mm to 2 mm.  
4.2 Specific requirements  
Granulated phosphate rock fertilizer shall comply with the requirements prescribed in Table 1. PUBLIC REVIEW DRAFTDEAS 905:2018  
© EAC 2018 – All rights reserved  Table 1 — Requirements for Granulated phosphate rock  
Characteristic  Requirement  Test method  
Total phosphate (as P 2O5) % by mass, 
min. 28.0 Annex A (I)  
Citric acid soluble phosphorus (as P 2O5) 
% by mass,  min. 9 Annex A (II)  
Calcium content (as CaO) % by mass, 
min. 35 Annex B  
Moisture, percent by mass, max.  7.5 Annex C  
5 Contaminants  
5.1 Heavy metal contaminants in the granulated phosphate rock fertilizer shall conform to 
the limits given in Table 2 whe n tested with the method specified therein  
Table 2 — Requirements for heavy metal contaminants  
Heavy metal  Requirement  Method of test  
Arsenic, mg/kg, max  20 
ISO 17318  Cadmium, mg/kg  P2O5, 
max 60 
Mercury, mg/kg, max  0.1 
Lead, mg/kg, max  30 
Chromium , mg/kg, max  500 
 
5.2 The radioactive elements found in the fertilizer materials shall not exceed the limit set 
by the respective country . 
6 Sampling  
Sampling of granulated phosphate  rock fertilizers shall be carried out in accordance with 
DEAS 913 . 
7 Packagin g and labeling  
7.1 Packaging  
The fertilizer shall be packaged in materials that are clean and non -defective that protect the 
product from physical, chemical and moisture contamination and withstand multiple stages of 
handling (transportation and stor age).  
7.2 Labeling  
Each package shall be indelibly labeled in English and/or any other language with the 
following information:  
a) fertilizer name, i.e. common name and brand name ; PUBLIC REVIEW DRAFTDEAS 905:2018  
  b) name and address of the manufacturer/packer ; 
c) net content by mass, in kilogram (kg) or tonnes ; 
d) nutrient content – Total phosphorus (% P2O5) by mass ; 
e) country of origin ; 
f) handling instructions – including the words ‘use no hooks’ ; 
g) production date ; 
h) batch number ; and  
i) storage conditions . PUBLIC REVIEW DRAFTDEAS 905:2018  
© EAC 2018 – All rights reserved  Annex A  
(normative)  
 
Determination of total phosphor us 
Reagents  
For the purpose of this East African Standard, only analytical grade reagents and distilled 
water given below shall be used.  
a) Concentrated hydrochloric acid.  
b) Concentrated nitric acid.  
c) Magnesium nitrate solution  
d) Citric molybdic acid reagent  
e) Quinoline solution  
f) Quimociac reagent  
NOTE: All the reagents above can be prepared as described below;  
A. Magnesium nitrate solution – Dissolve 950 g of P -free Mg (NO 3)2.6H2O in water and  
dilute to 1 L.  
B. 4.1.4 Citric molybdic acid reagent  – Dissolve 54 g of 100% molybdic anhydride 
(MoO 3) and  12 g NaOH with stirring in 400 mL hot water and cool. Dissolve 60 g citric 
acid in mixture of 140 mL HCl and 300 mL water and cool. Gradually add molybdic 
solution to citric acid solution while stirring. Cool, filter and dilut e to 1 L (solution may 
be green or blue colour, depending on exposure to light). If necessary, add 0.5 % 
KBrO 3 solution drop by drop until green colour becomes pale. Store in dark 
polyethylene bottle.  
C. Quinoline solution – Dissolve 50 mL synthetic quinoline  while stirring in mixture of 60 
mL HCl and 300 mL water. Cool, dilute to 1 L and filter. Store in polyethylene bottle.  
D. Quimociac reagent – Dissolve 70 g of sodium molybdate dihydrate in 150 mL water.  
Dissolve 60 g citric acid in mixture of 85 mL HNO 3 and 150 mL water and cool.  
Gradually add sodium molybdate solution to citric acid -nitric acid mixture while stirring 
(A). Dissolve 5 mL synthetic quinoline in mixture of 35 mL HNO 3 and 100 mL water 
(B). Gradually add this solution ( B) to solution ( A), mix an d let it stand for 24 h. Filter, 
add 280 mL acetone, dilute to 1 L with water and mix well. Store in polyethylene 
bottle.  
 
PROCEDURE  
For cases where preparation of reagents should be needed; the following procedures should 
be followed:  
Weigh 1 g of sampl e, treat with 15 -30 mL concentrated hydrochloric acid and 3 -10 mL 
concentrated nitric acid and digest till brown fumes cease, then dilute to 200 mL. Pipette into 
500 mL Erlenmeyer flask, aliquot containing not more than 25 mg P 2O5, dilute to 
approximately 100 mL with water. Proceed with one of the following methods:  
A. Add 30 mL citric molybdic acid reagent and boil gently for 3 minutes (solution must be  
precipitate free at this stage). Remove from heat and swirl carefully. Immediately add from 
burette 10 m L quinoline solution with continuous swirling (add first 3 -4 mL drop wise and 
remainder in steady stream) or  
B. Add 50 mL quimociac reagent, cover with watch glass, place on hot plate in well -ventilated  
hood and boil for one minute.  
After treatment with ei ther A or B, cool to room temperature; swirl carefully 3 -4 times during 
cooling. Filter into crucible with glass fibre filter paper or sintered glass crucible grade 4 (30 PUBLIC REVIEW DRAFTDEAS 905:2018  
  mL capacity), previously dried at 250 oC and weighed and washed five times with 25 mL  of 
water. Dry crucible and contents for 30 minutes at 250 oC. Cool in a desiccator to a constant 
weight and weigh.  
 
CALCULATION  
Total phosphorus (as P 2O5) % by mass = 0.03207 x (A – B) x F x 100  
 
W 
where,  
A = Weight of sample precipitates in gram;   
B = W eight of sample precipitates in gram for 
blank;  
W = Weight of sample;   
F = Dilution factor.  
 
 
II. Determination of citric acid soluble phosphorus content  
 
a) REAGENTS  
 
For the purpose of this East African  Standard, only analytical grade reagents and distille d 
water shall be used.  
 
a) Standard phosphate solution – Dilute 50 mL of stock phosphate solution to 250 mL with 
water (1 mL of this solution is equivalent to 0.2 mg P 2O5).  
 
b) Vanado -molybdate reagent – Dissolve separately 20 g of ammonium molybdate and 1 g of  
ammonium vanadate in hot water. Cool, mix and acidify with 140 mL concentrated nitric acid 
and dilute to 1 L.  
 
b) STANDARDIZATION OF INSTRUMENT  
 
Measure from a burette, into a series of 100 -mL volumetric flasks, 25.0 mL, 26.0 mL, 27.0 mL, 
28.0 mL, 29.0 mL,  30.0 mL, and 31.0 mL of the standard phosphate solution containing 5.0 
mg, 5.2 mg, 5.4 mg, 5.6 mg, 5.8 mg, 6.0 mg and 6.2 mg of P 2O5 respectively. Within five 
minutes for the entire series, add 25 mL of the vanadomolybdate reagent into each flask and 
dilute to 100 mL, ensuring that the temperature of the reagent and dilution water is maintained 
at 27 + 2 oC. Mix and allow to stand for ten minutes.  
 
If a single beam spectrophotometer is used, set the spectrophotometer to a wavelength of 
420 nm, fill two 1 -cm cells with the standard solution containing 5.0 mg P 2O5 to which the 
vanadomolybdate reagent has been added as given above and check the absorbance of the 
cells. If there is a small difference, select the cell with the lower reading as the standard 
reference cell.  
 
Using the other cell (sample cell), determine the apparent absorbance at 27 + 2 oC (corrected 
for cell differences) of the other standard solutions containing 5.2 mg, 5.4 mg, 5.6 mg, 5.8 mg, 
6.0 mg and 6.2 mg of P 2O5 referred to the solution co ntaining 5.0 mg P 2O5 as the standard. 
After each determination, empty and refill the cell containing the 5 -mg standard solution and 
readjust to zero absorbance to avoid errors that might arise from temperature changes. Plot a 
calibration graph of absorbanc e against concentration in mg P 2O5 per 100 mL of standard 
solution.  
 
NOTE – In the preparation of the standard phosphate solution, add to each flask, a volume of citric acid 
equal to the amount contained in the diluted sample solution mentioned in 5.1 (a) prior to the addition of 
the vanadomolybdate reagent.  
 
c) DISSOLUTION OF SAMPLE  
 
Weigh 1 g of prepared sample into a 250 -mL conical flask, add 100 mL of freshly prepared 2 
per cent citric acid, stopper and shake for 30 minutes using a mechanical shaker (set a -PUBLIC REVIEW DRAFTDEAS 905:2018  
© EAC 2018 – All rights reserved  shaking speed of twice per second), filter immediately.  
 
d) PROCEDURE  
 
A. Successively dilute a portion of the solution (volume V1 mL) prepared as in 5.1.2 , so that a 
final volume of about 25 mL contains between 5.5 mg P 2O5 and 6.2 mg P 2O5, taking care 
that the dilution water is at 27 + 2 oC.  
 
B. Transfer this solution to a 100 -mL volumetric flask, add 25 mL of the vanadomolybdate 
reagent (at a temperature of 27 + 2 oC), dilute to the mark, mix and allow to stand for 10 
minutes. At the same time, transfer 25 mL  of the standard phosphate solution (at 27 + 2 oC) 
into a second 100 -mL volumetric flask. Add sufficient citric acid such that when the   
solution is made up to 100 mL, its concentration is equal to that of the diluted sample solution. 
Add 25 mL of vanado molybdate reagent at 27 + 2 oC, dilute to mark, mix and allow to stand 
for 10 minutes.  
 
 
  PUBLIC REVIEW DRAFT 
   
C. Measure the difference in absorbance at 27  + 2 oC between the two solutions and  estimate 
the P 2O5 content of the sample solution using the calibration graph.  
 
e) CALCULATION  
 
Y     100       100 
Citric acid soluble P 2O5 content % by mass =      
1000 V1 M 
 
where,   
Y = graph reading, in mg/100 mL;   
V1 = volume (in mL) of sample solution diluted for test; 
M = mass (in gram) of the sample.  
 
 
 PUBLIC REVIEW DRAFT 
© EAC 2018 – All rights reserved  Annex B  
(normative)  
 
Determination of calcium oxide  
B.1 Reagents  
For the purpose of this East African Standard, only analytical grade reagents and distilled 
water shall be used . 
a) Concentrated hydrochloric acid.  
b) Concentrated nitric acid.  
c) Hydrofluoric acid – 40% 
d) Sodium carbonate  – solid 
e) Dilute hydrochloric acid – 1:1 (v/v)  
f) Ammonium chloride – solid 
g) Dilute acetic acid – 1:1 (v/v)  
h) Ammonium oxalate – solid 
i) Oxalic acid solution – 1g/L (m/v)  
j) Dilute sulphuric acid 1:4 (v/v)  
k) Standard potassium permanganate solution (0.1 N) – Dissolve3.2 g of potassium 
permanganate in 1 litre 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 standa rd 
sodium oxalate.  
B.2 Procedure  
For cases where preparation of reagents should be needed; the following procedures should 
be followed:  
B.2.1  Transfer 0.5g of sample that has been dried at 105 0C to a 400 -mL tall from beaker. 
Dissolve, by boiling gently w ith 20ml of concentrated hydrochloric acid and 10ml of 
concentrated nitric acid, until the volume is reduced to about 10ml. Covering the beaker by 
watch -glass throughout the process of dissolution, add 20ml 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 250ml measuring or 
volumetric flask. Preserve the filter and washings.  
B.2.2  Dry the residue and burn off the f ilter paper by ignition in a platinum crucible. Moisten 
the cooled residue with a few drops of a concentrated nitric acid and add about 10ml of 
hydrofluoric acid. Evaporate continuously just to dryness, ignite and fuse the residue with 
about 2 to 3 g of so dium carbonate. Extract the melt in about 25 -30ml of dilute hydrochloric 
acid in a beaker, evaporate to dryness and bake. Extract the baked mass with about 10ml of 
concentrated hydrochloric acid, dilute, filter and wash collecting the filtrate and washings  in PUBLIC REVIEW DRAFT 
  the same volumetric flask where in the first filtrate along with washings has been preserved 
under 5.1. Cool the combined filtrates and make up to the mark.  
B.2.3  Pipette out exactly 100ml from the solution in the volumetric flask under 5.2 into 
400ml -beaker. Add sufficient ammonium chloride (about 15ml) to hold magnesium in solution 
in presence of ammonium oxalate. Add 20ml of dilute acetic acid, heat to boiling point and 
add about 2g of ammonium oxalate while stirring. Boil and allow the precipitate t o settle for 1 
to 2 hours, cool and filter the solution through a close filter paper. Wash the precipitate with 
hot water until free from oxalate.  
B.2.4  Dissolve the precipitate on the filter in about 50ml of hot dilute hydrochloric acid. 
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 100ml by evaporation and re -precipitate calcium as oxalate under 5.3  
B.2.5  Wash the precipitate of calcium oxalate into same beaker in which precipitation was 
first carried out and treat the filter with about 25ml of warm (70 to 800C) dilute sulphuric acid 
for dissolving adhering precipitate of calcium oxalate. Wash the filter free fr om acid by means 
of hot water. Collect the washings also in the same beaker into which the precipitate was 
transferred. Add about 25ml more of dilute sulphuric acid and raise the temperature of 
contents to about 700C. When the precipitate has dissolved, ti trate with standard potassium 
permanganate solution until a permanent pale pink colour persists in solution.  
B.3 Calculation  
Calcium oxide % =
CFBA 100 (0.028)   
] 
where,  
A is the volume (in ml) of standard potassium permanganate solution ; 
B is the no rmality of the standard potassium permanganate solution ; 
C is the mass (in gram) of the sample represented by the aliquot taken ; 
F is the dilution factor . PUBLIC REVIEW DRAFT 
© EAC 2018 – All rights reserved  Annex C 
(normative)  
 
Determination of moisture content  
C.1 Oven dry method  
C.1.1  General  
The method d oes not apply to fertilizers that yield volatile substances other than water at 
drying temperature.  
C.1.2 Procedure  
C.1.2.1  Weigh accurately 2 g of the prepared sample in a pre -weighed, clean and dry 
weighing bottle or petridish.  
C.1.2.2  Heat in an oven fo r about 5 hours at 105  C + 2  C to constant weight. Cool in a 
desiccator and weigh. For urea, heat at 70  C + 5  C  for five hours to constant weight.  
C.1.3 Calculation  
Moisture per cent by weight (%) =  
ABCB

100  
where,  
A is the weight in gr am of the empty bottle;  
B is the weight of the bottle plus the material in gram, before drying;  
C is the weight of the bottle plus the material in gram, after drying . 
C.2 Vacuum desiccator method  
C.2.1  General  
The method is applicable to Ammonium Chloride,  Calcium Ammonium Nitrate (CAN), Di -
Ammonium Phosphate (DAP) and all types of complex and mixtures of NPK fertilizers.  
C.2.2 Procedure  
Weigh accurately in duplicate 5g of prepared sample in a weighed shallow porcelain dish. Put 
the sample in a desiccator o ver concentrated sulphuric acid, close and introduce vacuum for 
about 10 minutes, then stop the vacuum pump and leave the sample for 24 hours, then 
release vacuum, remove the sample from the desiccator and weigh.  
C.2.3 Calculation  
Moisture per cent by weig ht = 
) () (
100
1 23 2
W WW W

  PUBLIC REVIEW DRAFT 
  where,  
W1 is the Weight in gram of empty porcelain dish ; 
W2 is the Weight in gram of porcelain dish with sample before putting the sample for 24 
hours in the desiccator ; 
W3 is the Weight in gram of porcelain dish with sample af ter putting the sample for 24 
hours in the desiccator . 
C.3 Karl Fischer method  
C.3.1 General  
This method is applicable to fertilizers like CAN, Urea and urea based complexes. This 
method is not suitable for phosphate rock based fertilizers and fertilizers containing 
monocalcium phosphate, calcium sulphate, alkali carbonates as well as aldehydes and 
ketone groups.  
C.3.2 Apparatus  
Karl Fischer titrator  
C.3.3 Reagents  
C.3.3.1  Karl Fischer reagent(KF) – Karl Fischer solution (pyridine free) (single solution) . 
C.3.3.2  Di-sodium tartarate dihydrate (Na2C4O62H2O) analytical grade  
C.3.3.3  Methanol -KF grade/spectroscopy grade containing less than 0.05 % water . 
C.3.4 Procedure  
C.3.4.1  Standardization of KF reagent.  
C.3.4.1.1  Set up the instrument as per manufacturer’ s manual.  
C.3.4.1.2  Add methanol to the titration vessel until the electrodes are dipped and titrate with 
Karl-Fischer reagent to a pre -set end point persists for 30 seconds.  
C.3.4.1.3  Add 100mg of the disodium tartarate dehydrate to the titration vessel  carefully 
and titrate with Karl Fischer reagent to a pre -set end point (the pre -set end point should 
persist for 30 seconds). Note the volume of KF reagent used as V 1 ml. 
C.3.4.2  Determination of moisture of sample  
C.3.4.2.1  Weigh accurately 1 g of the pr epared sample and transfer to the titration vessel 
carefully and stir until dispersed.  
C.3.4.2.2  Titrate with KF reagent to the same pre -set end point as above and note the 
volume of KF reagent used as V 2 ml. 
C.3.5 Calculation  
Factor (F)(mgH 2O/1 ml of KF r eagent ) = 
1added dihy drate tartarate sodiumofmg 0.1566
V  PUBLIC REVIEW DRAFT 
© EAC 2018 – All rights reserved  Moisture per cent by weight = 
0001 (gram) sampleof Weight100 2
VF