GB/T 45891-2025Fertilizers and soil conditioners - Determination of humic and hydrophobic fulvic acids concentrations in fertilizer materials (English PDF)
肥料和土壤调理剂 肥料原料中腐植酸和疏水性黄腐酸含量的测定
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Issued by
State Administration for Market Regulation, China National Standardization Administration
Level / Type
National · Recommended
Issue date
June 30, 2025
Implementation date
January 1, 2026
Scope
GB/T 45891-2025 is the English-translated version of 肥料和土壤调理剂 肥料原料中腐植酸和疏水性黄腐酸含量的测定.
GB/T 45891-2025 is a Chinese national standard for determining humic acid and hydrophobic fulvic acid in fertilizers and soil conditioners. It is equivalent to ISO 19822:2018, with minor corrections to clause numbering, a sieve aperture and a chromatography column size.
The document describes the method used to measure the content of humic acid and hydrophobic fulvic acid. It applies to solid and liquid raw materials found in commercial fertilizers, soil conditioners and geological deposits.
Its terms include hydrophobic fulvic acid, humic acid, humic substance and lignosulfonates. Issued on 30 June 2025 and applicable from 1 January 2026, it is aimed at laboratories that need a consistent way of quantifying these fractions in fertilizer raw materials.
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Document preview — GB/T 45891-2025
National Standard of the People's Republic of China
- ICS
- 65.080
- Classification
- G 20
Issued by: State Administration for Market Regulation, China National Standardization Administration
Contents
- Foreword
- 1 Scope
- 2 Normative references
- 3 Terms and Definitions
Foreword
This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.
This document is equivalent to ISO 19822:2018 "Fertilizers and soil conditioners - Humic acid and hydrophobic fulvic acid content in fertilizer raw materials" Determination".
The following minimal editorial changes have been made to this document.
---Corrected the chapter and article numbering of the original international document, changing 5.3 and 5.4 of the original document to 5.2 and 5.3;
--- Corrected the inconsistency of sieve aperture size, changing 74µm to 75µm (see 7.21);
--- Corrected the inconsistency in the size of the hydrogen ion exchange chromatography column, changing 5cm×50cm to 5cm×60cm (see 14.2.2);
--- Increased formula numbers and replaced text with symbols (see Chapter 13).
1 Scope
This document describes the method for the determination of humic acid and hydrophobic fulvic acid.
This document applies to the humic and hydrophobic fulvic acid contents of solid and liquid raw materials in commercial fertilizers, soil conditioners and geological deposits. Determination of quantity.
2 Normative references
This document has no normative references.
3 Terms and Definitions
The following terms and definitions apply to this document.
The URLs for terminology databases used for standardization maintained by ISO and IEC are as follows. […]
3.1 Hydrophobic fulvic acid
The sulfur (S) content is less than 0.75%, soluble in alkaline and acidic aqueous solutions and can be absorbed by medium-polar polymers at pH = 1.
Substances adsorbed by the resin. The resin is used to adsorb amphiphilic compounds with a specific fulvic acid molecular weight.
3.2 Contains fulvic acid fraction
Contains fulvic acid components The part of the alkaline extract of humus that is soluble in both alkaline solution and acid solution.
3.3 Humic acid
humicacids; HA Humic base extract is insoluble in strong acidic solution and precipitates in acidic solution with pH=1.
3.4 Humic substance
The main organic components of natural organic matter are formed by biochemical reactions during the decay and transformation of plant and microbial remains. A complex and heterogeneous mixture of carbon-based substances.
3.5 Lignosulfonates
An amorphous, light brown to dark brown powder or liquid obtained from softwood pulping by the sulfite pulping process. Lignin is composed of three aromatic alcohols.
A sulfonated random polymer mainly composed of coniferyl alcohol (coniferyl alcohol, p-coumaryl alcohol and sinapyl alcohol).
......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 11 pages — is available in the English PDF.
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