PUBLIC REVIEW DRAFT  DRAFT UGANDA STANDARD  
  DUS 1661  
First Edition  
2017 -mm-dd 
 
 
 Reference number  
DUS 1661 : 2017 
© UNBS 2017   
  
Magnesium sulphate fertilizer — Specification  
 PUBLIC REVIEW DRAFTDUS 1661 : 2017  
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responsible for its cor rect application  
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 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 c o-
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 W orld 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, trader s, 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 t he draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
This Draft Uganda Standard has been developed as a result of a need to provide guidance to industry in 
production and regulation of Inorganic fertilizers . 
This Draft Uganda Standard was developed by the UNBS/TC 2/SC 20 – Agrochemicals and veterinary drugs 
Sub Committee under the Food and Agricu lture standards Technical Committee, UNBS/TC 2 . 
 PUBLIC REVIEW DRAFTPUBLIC REVIEW DRAFTDRAFT UGANDA STANDARD  DUS 1661 : 2017 
 
© UNBS 2017  – All rights reserved  1 
 Magnesium sulphate fertilizer — Specification  
1 Scope  
This Draft  Uganda  Standard specifies the requirements, methods of sampling and tests for magnesium 
sulphate fertilizer.  
2 Normative references  
The following referenced documents are indispensable for the application of this document. For dated 
references, only the e dition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies.  
AOAC 937.02, Magnesium (Water -soluble) in fertilizers  
AOAC 980.02 , Sulfur in fertilizers . 
AOAC 2006.03: Arsenic, Cadmium, Cobalt , Chromium, Lead, Molybdenum, Nickel, and selenium in fertilizers. 
Microwave digestion and inductively coupled plasma -optical emission spectrometry  
ISO 8157 , Fertilizers and soil conditioners —Vocabulary  
ISO 8633,  Solid fertilizers — Simple sampling method for small lots  
ISO 8634,  Solid fertilizers — Sampling plan for the evaluation of a large delivery  
3 Terms and definitions  
For the purposes of this standard, the definitions given in ISO 8157, Fertilizers and soil 
conditioners ─Vocabulary  shall apply . 
4 Requ irements  
4.1 Description  
The product  shall consist essentially of magnesium sulphate, and shall be in the form of a free flowing 
crystalline powder or granules .It shall be free from visible foreign matter.  
4.2 Physical  
If in granular form the particle siz e shall be such that not less than 90 % by mass shall be in the particle size 
range of 1 mm to 4 mm.  
4.3 Chemical  
The product  shall comply with the  chemical requirements provided  in table 1  PUBLIC REVIEW DRAFTDUS 1661 : 2017  
2 © UNBS 2017  – All rights reserved  
 Table 1 compositional limits  
SN Characteristic  Requirement  Test m ethod  
i) Water soluble 
magnesium 
content( as MgO )% by 
weight ,min  25.0 AOAC  937.02  
ii) Sulphate content as 
S (% by weight)min  20 AOAC 980.02  
iii) Moisture content,% 
by weight(max)  1.5 AOAC 965.08 B  
 
4.4 Heavy metal contaminants  
When tested in accordanc e with the methods specified therein, the heavy metal contaminants shall not 
exceed those indicated in Table 2.  
Table 2 — Heavy metal contaminants limits  
SN Parameter  Limits in mg/kg  Test method  
i) Arsenic, As, max.  20.0  
AOAC 2006.03  ii) Cadmium, Cd, ma x. 20.0 
iii) Mercury, Hg, max.  0.1 
iv) Lead, Pb, max.  30.0 
 
5 Packaging  
Magnesium sulphate  fertilizer shall be packaged in materials that ensure the product integrity and quality and 
protect it against physical damage, chemical and moisture contamina tion.  
6 Weights and Measures  regulations  
The fill of the package shall comply with the weight and measures act  
7 Labellin g 
The following information shall be clearly and indelibly marked  in English  on each package or container : 
a) name of the fertilizer as  “Magnesium sulphate”;  
b) name, address and physical location of manufacturer/packer/importer ; 
c) guaranteed percentage by mass of the water soluble magnesium and sulphur content ; 
d) date of manufacture ; 
e) expiry date ;  
f) batch/lot number ; PUBLIC REVIEW DRAFTDUS 1661 : 2017  
© UNBS 2016  – All rights reserved  3 
 g) the net weight of the fertiliz er in the package; in metric units ; 
h) Storage and Handling instructions ; 
i) instructions  for use ; 
j) disposal instructions  and; 
k) Country of origin.  
8 Sampling  
Sampling shal l be done in accordance with ISO 8633 and ISO 8634  PUBLIC REVIEW DRAFTDUS 1661 : 2017  
4 © UNBS 2017  – All rights reserved  
 Bibliography  
[1] KS 2220:2015 Magnesium su lphate fertilizer — Specification  
 PUBLIC REVIEW DRAFTDUS 1661: 2017  
© UNBS 2017  – All rights reserved  5 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is govern ed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The 
presence of this mark on a product or in relation to a product is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and testing in accordance with the 
certification mark scheme of the Uganda Natio nal Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
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