AFRICAN 
STANDARD  DARS  
1489 
First Edition 2018  
 
 Reference No. ARS 1489:2018 (E) 
ICS 65.080  
 
 
© ARSO 2018  
  
 
 
 
 
 
 
 
 
 
Single superphosphate fertilizer — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DARS  1489:2018  
ii © ARSO 2018 — All rights reserved   
Table of contents  
 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative ref erences  ................................ ................................ ................................ .....................  1 
3 Terms and definitions  ................................ ................................ ................................ .....................  1 
4 Requirements  ................................ ................................ ................................ ................................ . 1 
4.1 General  Description  ................................ ................................ ................................ ...............  1 
4.2 Physical requirements  ................................ ................................ ................................ ...........  2 
4.3 Chemical requirements  ................................ ................................ ................................ ..........  2 
4.4 Heavy metal contaminants  ................................ ................................ ................................ .... 2 
5 Sampling  ................................ ................................ ................................ ................................ .........  2 
6 Tests  ................................ ................................ ................................ ................................ ...............  2 
6.1 Methods of test  ................................ ................................ ................................ ......................  2 
6.2 Inspection ................................ ................................ ................................ ...............................  2 
7 Compliance  ................................ ................................ ................................ ................................ ..... 3 
8 Packaging a nd labelling  ................................ ................................ ................................ .................  3 
8.1 Packaging  ................................ ................................ ................................ ..............................  3 
8.2 Labelling ................................ ................................ ................................ ................................ . 3 
9 Certificate of analysis  ................................ ................................ ................................ .....................  3 
10 Material safety  ................................ ................................ ................................ ................................  3 
Annex A (normative)  Determination of free phosphoric acid  ................................ ................................ . 4 
 DARS 14 89:2018  
© ARSO 2018 — All rights reserved  iii  
Foreword  
 
The African Organization for Standardization (ARS O) is an African intergovernmental organization 
established by the United Nations Economic Commission for Africa (UNECA) and the Organization of 
African Unity (AU)  in 1977 . One of the fundamental m andates of ARSO is to develop and harmoniz e 
African Standards (ARS) for the purpose of enhancing Africa’s internal trading capacity, increase 
Africa’s product and service competitiveness globally and uplift the welfare of African communities.  
The work of p reparing African  Standards is normally carried out through ARSO  technical committees. 
Each Member State  interested in a subject for which a technical committee has been established has 
the right to be represented on that committee. International organizati ons, Regional Economic 
Communities (RECs), governmental and non -governmental  organizations , in liaison with ARSO , also 
take part in the work.  
 
ARSO  Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.  
 
The main task  of technical committees is to prepare ARSO  Standards. Draft ARSO  Standards 
adopted by the technical committees are circulated to the member bodies for voting. Publication as an 
ARSO  Standard requires approval by at least 75 % of the member bodies casting a vote.  
 
Attention is drawn to the possibility that some of the elements of this document may be the subject of 
patent rights. ARSO  shall not be held responsible for identifying any or all such patent rights.  
 
This African Standard was prepared by the ARSO  Technical Harmonization Committee Number 5 on 
Chemistry and Chemical Engineering (ARSO/THC 05) . 
 
 
 
 
 
© African Organisation for Standardisation  2018 — All rights reserved* 
 
ARSO Central Secretariat  
International House 3rd Floor  
P. O. Box 57363 — 00200 Cit y Square  
NAIROBI, KENYA  
 
Tel. +254 -20-2224561, +254 -20-3311641, +254 -20-3311608  
 
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Web: www.arso -oran.org  
                                                 
* 2018 ARSO — All rights of exploitation reserved worldwide for African Member States’ NSBs. 
 DARS  1489:2018  
iv © ARSO 2018 — All rights reserved   
 
Copyright  notice  
 
This ARSO document is copyright -protected by ARSO. While the reproduction of this document 
by participants in the ARSO standards development process is permitted without prior 
permission from ARSO, neither this document nor any extract from it may  be reproduced, stored 
or transmitted in any form for any other purpose without prior written permission from ARSO.  
 
Requests for permission to reproduce this document for the purpose of selling it should be 
addressed as shown below or to ARSO’s member bod y in the country of the requester:  
 
 
© African Organisation for Standardisation 201 8 — All rights reserved  
 
ARSO Central Secretariat  
International House 3rd Floor  
P.O. Box 57363 — 00200 City Square  
NAIROBI, KENYA  
 
Tel: +254 -20-2224561, +254 -20-3311641, +25 4-20-3311608  
 
 
E-mail: arso@arso -oran.org  
Web: www.arso -oran.org  
 
Reproduction for sales purposes may be subject to royalty payments or a licen sing agreement. 
Violators may be p rosecuted.  
 
 
 
 
 DARS 14 89:2018  
© ARSO 2018 — All rights reserved  1  
Single superphosphate fertilizer  — Specification  
 
 
1 Scope  
 
This African  Standard specifies the requirements , sampling and test  methods for single 
superphosphate fertilizer.  
 
2 Normative references  
 
The following referenced documents are indispensable for the application of this document. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies.  
 
AOAC 20 06.03 , Arsenic, cadmium, cobalt, chromium, lead, molybdenum, nickel, and selenium in 
fertilizers  — Microwave digestion and inductively coupled plasma -optical emission spectrometry  
 
EN 12048, Solid fertilizers and liming materials — Determination of moistur e content — Gravimetric 
method by drying at 105 2 C 
 
EN 13475, Liming materials — Determination of calcium content — Oxalate method  
 
EN 16032, Fertilizers — Extraction and determination of elemental sulfur  
 
ISO 5316, Fertilizers — Extraction of water -soluble phosphates  
 
ISO 6598 , Fertilizers — Determination of phosphorus content — Quinoline phosphomolybdate 
gravimetric method  
 
ISO 7409, Fertilizers — Marking — Presentation and declarations  
 
ISO 8157, Fertilizers and soil conditioners — Vocabulary  
 
ISO 8397, Solid fertilizers and soil conditioners — Test sieving  
 
ISO 11047, Soil quality — Determination of cadmium, chromium, cobalt, c opper, lead, manganese, 
nickel and zinc — Flame and electrothermal atomic absorption spectrometric methods  
 
ISO 14820 -1, Fertilizers and liming materials — Sampling and sample preparation — Part 1: 
Sampling  
 
ISO 14820 -2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample 
preparation  
 
ISO 15178, Soil quality — Determination of total sulfur by dry combustion  
 
ISO 17318, Fertilizers and soil conditioners — Determination of arsenic, cadmium, chromium, lead 
and mercury contents  
 
3 Terms and definitions  
 
For the purpose of this standard , the terms and definitions in ISO 8157  apply.  
 
4 Requirements  
 
4.1 General Description  
 
The fertilizer shall be in the form of free flowing powder or granules.  It shall be free from hard lumps , 
foreign matter and shall not cake on storage  AFRICAN STANDARD  DARS 14 89:2018  
2 © ARSO 2018 — All rights reserved   
4.2 Physical  requirements  
 
When test sieved in accordance with ISO 8397, t he particle size for granular fertilizer shall be such 
that not less than 90 %, by mass of the fertilizer shall be of particles in the size range of 1 mm to 4 
mm. Not more than 5% shall be below 1 mm . 
 
4.3 Chemical  requirements  
 
 Single superphosphate fertilizer shall comply with the following compositional limits.  
 
Table 1 — Chemical requirements  
 
Parameters  Requirements  Method of test  
Granules  Powder  
Water soluble phosphate, P 2O5, %, m/m , min. 15.8 15.8 ISO 5316  
Free phosphoric acid, as P 2O5, % m/m, max.  4 4 Annex A  
Moisture content, % m/m, max.  5 512 EN 12048  
Sulphur as S, % m/m, min. 11 11 ISO 15178/ EN 16032  
 
4.4 Heavy metal conta minants  
 
The presence of heavy metal contaminants shall not exceed the limits stipulated in Table 2.  
 
Table 2 — Heavy metal contaminants  
 
Parameter  Maximum limit, mg/kg  Test method  
Arsenic, As  10.0 ISO 17318  
Cadmium, Cd  7.0 ISO 17318  
Mercury, Hg  0.1 ISO 17318  
Selenium, Se  1.0 AOAC 2006.03  
Lead, Pb  30.0 ISO 17318  
Chromium, Cr, max.  50.0 ISO 17318/ ISO 11047  
 
5 Sampling  
 
Sampling shall be carried out in accordance with ISO 14820 -1. 
 
6 Tests  
 
6.1 Methods of test  
 
Samples of the fertilizer  shall be prepared in accordance with ISO 14820 -2 and tested in  accordance 
with the methods of test indicated in  Table 1  and Table 2 . 
 
6.2 Inspection  
 
From the bulk sa mples obtained from ISO 14820 -1, inspect the lot for the characteristics relating  to 
the packing and m arking of the product.  
 
 
 DARS 14 89:2018  
© ARSO 2018 — All rights reserved  3 7 Com pliance  
 
The lot shall be deemed to comply with the standard  if after inspection and testing it complies with the  
require ments of this standard.  
 
8 Packaging and labelling  
 
8.1 Packaging  
 
The fertiliser shall be packed in cle an, non -defective and strong containers.  The material for which the 
container is made shall be such as to protect the contents from moisture and also not lead to easy 
rupture during handling, transportation and storage.  
 
8.2 Labelling  
 
8.2.1  Each container  of the fertiliser shall bear a label in indelible marking in accordance with ISO 
7409, the Globally Harmonized System (GHS) and with the following particulars:  
 
a) type of the fertilizer, as “ Single superphosphate fertilizer ”  
 
b) brand name  
 
c) name, address an d physical location of the manufacturer/packer/importer;  
 
d) country of origin/manufacture;  
 
e) date of manufacture  
 
f) best before date  
 
g) the content net weight;  
 
h) batch/lot number;  
 
i) storage instructions;  
 
j) handling instructions ; 
 
k) instructions for use ; 
 
l) instructions  for disposal of used containers . 
 
m) form of fertilizer  (granular or powdered)  
 
8.2.2  Bulk containers  
 
Where the fertilizer  is distributed in bulk, the marking  information shall acco mpany the delivery notice 
to the purchaser.  
 
9 Certificate of analysis  
 
A cer tificate of analysis stating the mini mum percentage levels of plant nutrient elements shall 
accompany every lot or consign ment of  the fertilizer.  
 
10 Material safety  
 
Each container must be accompanied by a Material Safety Data Sheet (MSDS) and Technical D ata 
Sheet (TDS).  DARS 14 89:2018  
4 © ARSO 2018 — All rights reserved   
Annex A  
(normative)  
 
Determination of free phosphoric acid  
 
 
 
A.1 Purpose  
 
This method determines the percent of phosphoric acid (P 2O5) in commercial fertilizers by colorimetry.  
 
A.2 Reagents and apparatus  
 
1) An Atomic Absorption Spectr ophotometer or a suitable colorimeter.  
 
2) Nitric Acid (HNO 3), 1.42 specific gravity.  
 
3) Hydrochloric Acid (HCl), 1.19 specific gravity.  
 
4) Potassium Phosphate, Monobasic (KH 2PO 4), Primary Standard Grade, dried at 105 -110 °C 
for several hours prior to  use.  
 
5) Ammonium Molybdate ((NH 4)6MO 7O24•4H 2O), Reagent Grade.  
 
6) p-Methylaminophenol Sulfate, Reagent Grade.  
 
7) Sodium Acid Sulfite (NaHSO 3), Reagent Grade.  
 
8) Cuvets, optical glass, matched, 10mm path length.  
 
NOTE  If available, an optical glas s, automatic flow -through cuvet may be used.  
 
A.3 Preparation of standard solutions  
 
Phosphate Stock Solution:  Weigh 0.4394 g of dried, primary standard KH 2PO 4 into a 500 - mL 
volumetric flask. Add 30 ml of HNO 3 and 5 ml of HCl and boil until brown fumes ha ve been expelled. 
Dilute to volume with distilled water.  
 
5 ppm Working Standard:  Pipette a 5 -ml aliquot of the phosphate stock solution into a 200 -ml 
volumetric flask and dilute to volume with distilled water. This solution is equivalent to 57.2% 
phospho ric acid.  
 
4 ppm Working Standard:  Pipette a 4 -mL aliquot of the phosphate stock solution into a 200 -mL 
volumetric flask and dilute to volume with distilled water. This solution is equivalent to 45.8% 
phosphoric acid.  
 
Blank Working Solution:  Boil a mixt ure consisting of 5 ml of HCl and 30 ml of HNO 3 until brown 
fumes have been expelled, transfer to a 500 -ml volumetric flask and dilute to volume with distilled 
water. Transfer a 4 -ml aliquot to a 200 -ml volumetric flask and dilute to volume with distilled water.  
 
A.4 Preparation of colour development solutions  
 
Acid Molybdate Solution:  Pour, with stirring, a solution containing 16.62 g of ammonium molybdate 
in 156.9 ml of distilled water into a solution of 318.4 ml of HCl to which 29.6 ml of distilled wate r has 
been added.  
 
Reducing Solution:  Dissolve 1.0 g of p -methylaminophenol sulfate and 3.0 g of sodium acid sulfite in 
100 ml distilled water.  
 DARS 14 89:2018  
© ARSO 2018 — All rights reserved  5 A.5 Procedure  
 
Weigh, to the nearest 0.1 mg, 0.50 ± 0.02 g of sample into a 500 -ml volumetric flask, adding 3 0 ml of 
HNO 3 and 5 ml of HCl. Boil until brown fumes have been expelled, cool to room temperature and 
dilute to volume with distilled water. Transfer a 2 -ml aliquot to a 100 -ml volumetric flask and dilute to 
volume with distilled water. From this second di lution, transfer a 10 -ml aliquot to a 20 -ml scintillation 
vial and add a 2 -ml aliquot of acid molybdate solution and a 2 -ml aliquot of reducing solution. Allow to 
stand 1 hour for color development. At the same time that the sample vial is prepared, a blan k vial, a 
4 ppm phosphorus vial and a 5 ppm phosphorus vial must also be prepared and allowed to develop 
color along with the sample. The blank, 4 ppm phosphorus and 5 ppm phosphorus are prepared by 
the same procedure used for preparation of the sample, us ing 10 -ml aliquots of the blank working 
solution, the 4 ppm phosphorus working standard and the 5 ppm phosphorus working standard.  
 
NOTE  When making determinations on fertilizers with low percentages of phosphoric acid, it is necessary to adjust the 
sampl e weight so that the sample working dilution contains between 4 ppm and 5 ppm phosphorus.  
 
Calibrate the instrument using the blank solution, the 4 ppm phosphorus solution and the 5 ppm 
phosphorus solution, then determine the concentration of the sample so lution.  
 
NOTE  When using an Atomic Absorption Spectrophotometer for colo ur measurements, the cuvet holder is placed over the 
burner in the light path and a Cu hollow cathode lamp is used with the instrument grating set at a wavelength of 640 nm.  
 
A.6 Calcu lations  
 
The method of calculating the  % phosphoric acid will vary according to the make and model of 
instrument used. Report the results to the nearest 0.1% P 2O5 as follows:  
 
% Phosphoric Acid (P 2O5)  
 
 
 
 
 
 DARS 14 89:2018 
© ARSO 2018 — All rights reserved