DRAF T UGANDA STANDARD  
  DUS 757 
Second  Edition  
2017 -mm-dd 
 
 
 Reference number  
DUS 757 
© UNBS 2017   
  
Ammonium  sulphate  nitrate fertilizer — Specification  
 DUS 757 
ii © UNBS 2017 – 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 2017  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without prior writt en 
permission from UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
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Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 757 
© UNBS 2017 – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements  ................................ ................................ ................................ ................................ .........  1 
4.1 General requirements  ................................ ................................ ................................ ...........................  1 
4.2 Specific requirements  ................................ ................................ ................................ ...........................  2 
4.3 Heavy metal contamination  ................................ ................................ ................................ ..................  2 
5 Packaging  ................................ ................................ ................................ ................................ ...............  2 
6 Weights and Measures regulations  ................................ ................................ ................................ ..... 2 
7 Labelling  ................................ ................................ ................................ ................................ .................  3 
8 Sampling  ................................ ................................ ................................ ................................ ................  3 
Annex  A (normative)  Determination  of free acidity  ................................ ................................ ........................  4 
A.1 Reagents  ................................ ................................ ................................ ................................ ................  4 
A.2 Procedure  ................................ ................................ ................................ ................................ ...............  4 
A.3 Calculations  ................................ ................................ ................................ ................................ ...........  4 
Bibliography  ................................ ................................ ................................ ................................ ........................  5 
 DUS 757 
iv © UNBS 2017 – All rights reserved  
 Foreword  
Uganda National Bureau of Standards (U NBS) 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 Stand ardisation (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 Tec hnical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of key stakeholders 
including government, academia, consumer groups, private sector and other interested parties.  
Draft Uganda Standar ds 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 Sta ndards Council.  
The committee responsible for this document is Technical Committee UNBS/TC 2, Food and agriculture , 
Subcommittee SC 2 0, Agrochemicals and veterinary drugs . 
This second edition cancels and replaces the first edition ( US 757:2007 ), which has been technically revised.  
 DRAFT UGANDA STANDARD  DUS 757 
 
© UNBS 2017  – All rights reserved  1 
 Ammonium  sulphate  nitrate fertilizer — Specification  
1 Scope   
This Draft Uganda  Standard  specifies  requirements,  sampling  and test methods for ammonium  sulphate  
nitrate  (ASN) fertilizer.  
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 (inclu ding any amendments) applies.  
AOAC 950.01, Water (Total) in fertilizers  
ISO 5315,  Fertilizers — Determination of total nitrogen content -- Titrimetric method after distillation  
ISO 8157 , Fertilizers and soil conditioners —Vocabulary  
ISO 8397 , Solid fertilize rs and soil conditioners — Test sieving  
ISO 8633,  Solid fertilizers — Simple sampling method for small lots  
ISO 8634,  Solid fertilizers — Sampling plan for the evaluation of a large delivery  
ISO 15604,  Fertilizers — Determination of different forms of nitrog en in the same sample, containing nitrogen 
as nitric, ammoniacal, urea and cyanamide nitrogen  
ISO 17318 , Fertilizers and soil conditioners —Determination of arsenic, cadmium, chromium, lead and mercury 
contents  
3 Terms and definitions   
For the purposes of t his document, the terms and definitions given in ISO 8157 apply.  
ISO and IEC maintain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  
4 Requirements  
4.1 General requirements  
a) The material shall be free -flowing and in a form suitably coated so as to  retard caking and moisture  
absorption.   
2 © UNBS 2017  – All rights reserved  
 b) It shall be in the  form of uniform granules or crystals, free from any foreign matter.  
c) Particle size: Not less than 90 % o f the material shall pass through 4 mm IS sieve and be retained on 
1 mm IS sieve. Not more than 5 % shall be below 1 mm size  when tested in accordance with ISO 
8397 . 
4.2 Specific requirements  
The material  shall consist  essentially  of a double  salt of ammon ium sulphate  and ammonium  nitrate.  It shall  also 
comply  with the requirements  given  in Table  1 when  tested  in accordance  with the methods specified therein  
Table  1 — Chemical requirements  
Sn parameter  Requirements,  
% by mass  Test method  
i.  Nitra te nitrogen,  as N 26.0 max  ISO 15604  
ii.  Nitrogen content, as N  7.0 max  ISO 5315  
iii.  Free acidity, as HNO 3 0.015 max  Annex A  
iv.  Moisture content  1.0 max  AOAC 950.01  
 
4.3 Heavy metal contamination  
When tested in accordance with the methods specified therein, the heavy meta l contaminants shall not 
exceed those indicated in Table 2  
Table 2 — Limits for heavy metal contaminants  
Metal  Maximum limits,  
mg/kg  Test methods  
Arsenic  50 
ISO 17318  Cadmium  20 
Mercury  5 
Lead  30 
Chromium  150 
 
5 Packaging  
Ammonium sulphate nitra te fertilizer shall be packaged in materials that ensure the product integrity and 
quality and protect it against physical damage, chemical and moisture contamination.  
6 Weights and Measures regulations  
The fill of the package shall comply with the weight s and measures act  DUS 757 
© UNBS 2017 – All rights reserved  3 
 7 Labelling  
The following information shall be clearly and indelibly marked  in English  on each package or container : 
a) name of the fertilizer as  “Ammonium sulphate  nitrate”;  
b) name, address and physical location of manufacturer/packer/impor ter; 
c) chemical composition of the fertilizer;  
d) nitrogen content of the material as a percentage by weight ; 
e) date of manufacture;  
f) expiry date ;  
g) batch/lot number ; 
h) the net weight of the fertilizer in the package; in metric units ; 
i) storage and h andling instruction s; 
j) risk warning;  
k) instructions  for use ; 
l) disposal instructions  and; 
m) country of origin.  
8 Sampling  
Sampling shal l be done in accordance with ISO 8633 and ISO 8634   
4 © UNBS 2017  – All rights reserved  
 Annex  A 
(normative)  
 
Determination  of free acidity  
A.1 Reagents  
A.1.1  Standard sodium hydroxide solution,  0.02 N  
A.1.2  Methyl  red – methylene  blue mixed  indicator,  prepared  by mixing  equal  volumes  of 0.2 % methyl  
red solution in alcohol and 0.1 % methylene blue solution in alcohol  
A.2 Procedure  
Weigh accurately  10 g of the material and dissolve in 10 0 mL of neutral water at room temperature in a beaker  
or conical  flask.  Add 2 drops  to 3 drops  of the mixed  indicator  solution  (C 1.2) and titrate  with the sodium  
hydroxide  solution (C.1.1) until the colour changes  from violet to green.  
A.3 Calculations  
Free acidity, expressed  as a percentage  by mass of:  
mVT6.8
HNO3
 
where, 
V is the volume, in millilitres, of the standard sodium hydroxide solution used in the titration;  
T is the exact normality, of the sodium hydroxide solution, and  
m is the mass , in grams, of the test portion.  
 DUS 757 
© UNBS 2017 – All rights reserved  5 
 Bibliography  
[1] US 758:2007, Ammonium sulphate  nitrate fertilizer —— Specification  
[2] FAO Mineral fertilizer Specifications 2010  
[3] Agricultural Chemicals (Control) Act, 2006 (Act No.1 of 2007)  
[4] The Fertilizer Contr ol Regulations, 2010  
 US 757 
© UNBS 2017  – All rights reserved  7 
 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 governed by the St andards 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 thi s 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 National Bureau o f 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.  
 
 DUS 757   
 
ICS 65.080 
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© UNBS 2017 – All rights reserved