ISO/DIS 19747

Fertilizers and soil conditioners -- Determination of monosilicic acid concentrations in nonliquid fertilizer materials

Détermination des concentrations en silicium soluble dans les matières fertilisantes non liquides

Standards Content (sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 19747
ISO/TC 134 Secretariat: ISIRI
Voting begins on: Voting terminates on:
2018-09-11 2018-12-04
Fertilizers and soil conditioners — Determination of
monosilicic acid concentrations in nonliquid fertilizer
materials

Détermination des concentrations en silicium soluble dans les matières fertilisantes non liquides

ICS: 65.080
THIS DOCUMENT IS A DRAFT CIRCULATED
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ISO/DIS 19747:2018(E)
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NOTIFICATION OF ANY RELEVANT PATENT
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PROVIDE SUPPORTING DOCUMENTATION. ISO 2018
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ISO/DIS 19747:2018(E)
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ii © ISO 2018 – All rights reserved
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ISO/DIS 19747:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative References ..................................................................................................................................................................................... 1

3 Terms and Definitions .................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Safety ................................................................................................................................................................................................................................ 1

6 Reagents ........................................................................................................................................................................................................................ 1

7 Calibration Standards ..................................................................................................................................................................................... 2

8 Apparatus ..................................................................................................................................................................................................................... 3

9 Procedure..................................................................................................................................................................................................................... 4

9.1 Sample Preparation ............................................................................................................................................................................ 4

9.2 Extraction .................................................................................................................................................................................................... 4

9.3 Heteropoly Blue Analyses .............................................................................................................................................................. 4

9.4 Manual Spectrophotometer Analyses ................................................................................................................................. 5

9.5 Calculations ................................................................................................................................................................................................ 5

9.6 Precision ....................................................................................................................................................................................................... 6

9.7 Statistical Analysis ............................................................................................................................................................................... 6

9.8 Ring Study ................................................................................................................................................................................................... 6

Annex A (Informative) Report of the International Laboratories Ring Study ...........................................................7

Bibliography ................................................................................................................................................................................................................................ 8

© ISO 2018 – All rights reserved iii
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ISO/DIS 19747:2018(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national

standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations,

governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International 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 International Standards. Draft International

Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International 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. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 19747 was prepared by Technical Committee ISO/TC 134 for fertilizers and soil conditioners.

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ISO/DIS 19747:2018(E)
Introduction

Although Silicon is ubiquitous in nature, making up a quarter of the earth's crust (1), not all forms of

silicon found in soils or fertilizer products are soluble and plant-available (2,3). The form of silicon in

soils that is soluble and available for plant uptake is monosilicic acid. Worldwide, it has been estimated

that annual removal of silicon from soils during crop production can amount to 239-255 mega tons

annually based on FAO 1998 global crop production estimates and a conservative annual increase of

1 % through 2012. Although the first U.S. patent on a solid Si fertilizer was issued in 1881 (4), fertilizer

manufacturers, governmental regulators and consumers had no means of evaluating nonliquid silicon

fertilizer materials for their monosilicic acid supplying capacity to meet and replace plant uptake needs.

The first research into the use of silicon fertilizers was reported in 1840 (5). Additionally, increased

plant silicon concentrations were first associated with reductions in rice (Oryza sativa L.) blast disease

(Magnaporthe grisea M.E. Barr) over a century ago in Japan (6). Since then, research has extended to

other grasses and grains (e.g. barley (Hordeum vulgare L.) (7), corn (Zea mays L.) (8), oats (Avena sativa

L.) (9), wheat (Triticum aestivum L.) (10), sugarcane (Saccharum officinarum L.) (11), pasture (12), turf

grasses (13), and to dicotyledonous crops (e.g. cucumber (Cucumis sativus L.) (14), grapes (Vitis vinifera

L.) (15), pepper (Capsicum L.) (16), pumpkin (Curcubita pepo L.) (17), soybean (Glycine max (L.) Merr.)

(18), tomato (Solanum lycopersicum L.) (19)). Beneficial effects from silicon fertility have included

increased stress tolerance (disease, insect, drought, salt, nutrient imbalance, UV-rays, low and high

temperature) and yield increases with or without stress (2). Other benefits from silicon supplements to

soils have included CO sequestration (20), reductions in metals toxicity (21), and reduced phosphorus

run-off while increasing phosphorus use efficiency (22).

Considering the extensive research, a growing market, and the potential benefits from silicon fertility

to global agriculture; it is important that a standard method exist to enable regulation of nonliquid

silicon fertilizer materials based on their monosilicic acid supplying capacity. This is the first method

developed which correlates well with plant silicon uptake while using commonly available laboratory

equipment at a reasonable cost for the analysis.
© ISO 2018 – All rights reserved v
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DRAFT INTERNATIONAL STANDARD ISO/DIS 19747:2018(E)
Fertilizers and soil conditioners — Determination of
monosilicic acid concentrations in nonliquid fertilizer
materials
1 Scope

This document establishes a method for the determination of monosilicic acid concentrations in

nonliquid fertilizer materials. Monosilicic acid is reported as % Si.

This extraction method is applicable to the detection of monosilicic acid in nonliquid fertilizer products,

blended products, and beneficial substances at silicon (Si) concentrations of 0,2 to 8,4 %, with a Limit

of Detection (LOD) of 0.06 % Si, and a Limit of Quantification (LOQ) of 0,20 % correlating well with

plant uptake.

This method is not recommended for liquid silicon fertilizer sources due to an expected low bias of Si

recovery and low correlation with plant uptake.
2 Normative References

The following referenced documents, in whole or in part, are normatively referenced in this document

and are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 3696:1995, Water for Analytical Laboratory Use — Specification and Test Methods

ISO/DIS 8157, Fertilizers and Soil Conditioners — Vocabulary
3 Terms and Definitions
3.1
monosilicic acid

monosilicic acid is an inorganic molecule that is soluble in soil solution and is the form of silicon

available for plant uptake
4 Principle

Monosilicic acid (reported as % Si) from nonliquid Si fertilizer sources is extracted at ambient room

temperature using a dilute Na CO -NH NO extractant. The extractant solution is analyzed by manual

2 3 4 3
spectrophotometry at 660 nm using the heteropoly blue method.
5 Safety

5.1 General Requirements: A minimum of standard laboratory personal protective equipment including

safety glasses, gloves, and lab coats should be worn always. Consult individual SDS for chemicals listed

and follow safety and handling conditions per individual SDS instructions.
6 Reagents

6.1 General Requirements: Protect from sunlight. Store all reagents in a manner consistent with

general laboratory practices. Store in temperatures between 20-24 °C unless otherwise noted.

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ISO/DIS 19747:2018(E)

6.2 Sodium Carbonate solution: 0,094 M- Fill a 19 l plastic dispensing bottle with 18 l water. Add 180 g

anhydrous Na CO . Stir to dissolve.
2 3

6.3 Ammonium Nitrate solution: 0,20 M- Fill a 19 l plastic dispensing bottle with 18 l water. Add 288 g

NH NO . Stir to dissolve.
4 3

NOTE Ammonium Nitrate (NH NO ): Is a strong oxidizing agent and should not be used near flames, heating

4 3

or ignition sources, combustible materials, or reducing agents to avoid the potential for combustion or explosion

hazards. NH NO must be separated from all organic materials present within the laboratory. Check with

4 3

governmental agencies for any additional regulatory licensing requirements before obtaining or using NH NO .

4 3

6.4 Sodium Carbonate-Ammonium Nitrate extractant solution: 9,4 pH - Add 50 ml of each solution

(6.1 & 6.2) to a plastic beaker, stir, and verify a pH of 9.4 for the mixed solution using a pH meter.

NOTE Mixing of Sodium Carbonate and Ammonium Nitrate: Flexible vinyl gloves are to be worn when

mixing Na CO and NH NO , due to the caustic nature of this extractant. Care must be taken to avoid eye or skin

2 3 4 3

contact. If contact is made with eyes or skin, flush immediately with clean tap water and seek medical attention.

Clean up any spills immediately.

6.5 Silicon 1000 mg/l Stock Solution: Silicon Standard - This solution preferably 2 % Sodium Hydroxide

is commercially available from numerous sources. Follow specific manufacturer’s SDS for proper storage

and shelf life.

6.6 Silicon spike solution: 500 mg/l- Pipette 50 ml of a stock 1000 mg/l Silicon standard into a 100 ml

volumetric flask. Dilute to 100 ml with water.

6.7 Ammonium Molybdate solution: 0,42 M- Add 75 g ammonium molybdate [(NH ) Mo O · 4H O]

4 6 7 24 2

to a 1 l beaker. Add 500 mL water. Dissolve. Slowly add 100 mL concentrated (18.4 M) sulfuric acid

(H SO ). Cool. Transfer to a 1 l volumetric flask. Dilute to 1 l with water.
2 4

NOTE Handling of Concentrated Sulfuric Acid: Gloves, safety goggles, face shields, and lab coats should

always be worn when handling concentrated sulfuric acid. Sulfuric acid is extremely corrosive and dehydrating,

causing severe burns. Care must be taken to avoid eye or skin contact. If contact is made with eyes or skin, flush

immediately with clean tap water and seek immediate medical attention. To avoid the potential for fuming and

spattering of concentrated sulfuric acid during dilution, always add sulfuric acid to water and do not add water

to sulfuric acid.

6.8 Tartaric Acid solution: 1,33 M-M- Add 200 g tartaric acid to a 1 l beaker. Add 700 ml water. Stir.

Transfer to a 1 l volumetric flask. Dilute to 1 l with water.

6.9 Ascorbic Acid solution: 0,017 M- Add 3 g ascorbic acid to 1 l volumetric flask. Dilute to 1 l with

water. Stopper the flask and mix by inverting 10 times. Transfer to a plastic storage bottle. Cap tightly and

refrigerate.

6.10 Intermediate Silicon standard solution: 50 mg/l- Dilute 5 ml of a stock 1000 mg/l Silicon standard

to 100 mL in a volumetric fla
...