ISO/TC 134/WG 1 - Fertilizers

This document specifies general requirements for the testing, sampling and preparation of test samples and the marking, labelling, packaging, transport and storage of compound fertilizers. This document is applicable to inorganic solid compound fertilizers. This document is not applicable to controlled-release compound fertilizers.

This document specifies a method for the determination of total nitrogen content in all nitrogen containing fertilizers by combustion method. NOTE 1 The presence of non-nutritive sources of nitrogen (e.g. chelating agents) causes positive bias to samples being analysed for nutritive nitrogen content. The non-nutritive nitrogen content is subtracted from the total nitrogen value to determine the nutritive nitrogen content. NOTE 2 Common internationally traded fertilizers were evaluated for total nitrogen by combustion analysis in the ring-study in this document. While the fertilizers analysed in this international ring study were mineral fertilizers, previous studies have shown that total nitrogen by combustion is suitable for use with many non-mineral, nitrogen-containing fertilizers.

This document specifies the method for the determination of the EDTA soluble phosphorus content of inorganic fertilizers. The method is applicable for fertilizers composed of or blended from multiple sources such as superphosphate, ammonium phosphate, triple superphosphate, and/or nitrophosphate. It is not suitable for fertilizers containing calcium magnesium phosphates.

This document specifies a method to measure the total sulfur content in fertilizer and soil conditioner materials. This method is applicable for measuring total sulfur concentration in solid and liquid fertilizers and its raw inputs in the range of 0,1 % to 97 %.

This document establishes a method for the determination of monosilicic acid concentrations in nonliquid fertilizer materials. Monosilicic acid is reported as silicon (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 2 to 84 g/kg, with a limit of detection (LOD) of 0,6 g/kg Si, and a limit of quantification (LOQ) of 2 g/kg correlating well with plant uptake. This method is not applicable to liquid silicon fertilizer sources due to an expected low bias of Si recovery and low correlation with plant uptake.

This document specifies the test procedure for the determination of the salt out temperature (SOT), also known as the crystallization temperature (CT) of liquid (fluid) fertilizers, using an inexpensive and simple technique. This method might not be applicable to the binary and ternary fertilizers, especially with regards to the last crystal to disappear (LCTD). Some of these exceptions are discussed in the procedure (Clause 8).

ISO 21263:2017 specifies a method for the determination of the slow release properties of nutrients from coated fertilizers. pH-dependent hydrolysis and degradation by biological or microbial mechanisms are excluded. The specified method is only applicable to products releasing any nutrients by means of a non-biological process (i.e. those where the nutrients are released by a physical mechanism). Microbial attack on the coating (e.g. sulfur coated fertilizers) and the consequences thereof are not measurable by the technique described. This method involves a lengthy process which may not be appropriate for day to day testing purposes. Accelerated methods can be used provided they are correlated with this document. An example of such an accelerated method is described in Annex B. Regression analysis can also be used for this purpose.

ISO 19670:2017 specifies general requirements, analytical methods, sampling and preparation of test sample, marking and labelling, packaging, transport and storage for solid urea aldehyde slow release fertilizer. ISO 19670:2017 applies to pure solid urea aldehyde slow release fertilizer, i.e. urea formaldehyde (UF), methylene urea (MU), crotonylidene diurea (CDU), isobutylidene diurea (IBDU). This document does not apply to mixtures of nitrogenous fertilizers containing solid urea aldehyde slow release fertilizer.

ISO 19746:2017 specifies the test procedure for determining the urea content in urea-based fertilizers, including urea, urea aldehydes [methylene urea fertilizers, isobutylene diurea (IBDU), crotonylidene diurea (CDU)], urea triazone fertilizers, urea ammonium nitrate (UAN), sulfur- and polymer-coated urea (SCU and PCU), as well as compound fertilizers containing urea. The method is based on High Performance Liquid Chromatography (HPLC). The proposed method is an extension of the AOAC Official Method 2003.14 which was collaboratively studied for the "Determination of Urea in Water-Soluble Urea-Formaldehyde Fertilizer Products and in Aqueous Urea Solutions" in 2003. The method was published in the Journal of AOAC in 2004[4] and was granted the First Action in 2003 and the Final Action in 2008. This method also applies to the determination of biuret content in urea containing fertilizer with the results published in the J. AOAC in 2014[5]. This method was adopted by the International Organization for Standardization (ISO) as a Committee Draft (ISO/CD 18643) in 2014, and after review and the Ring Test Analyses[6].

ISO 18642:2016 specifies the general requirements regarding testing methods, sampling and preparation of test sample, marking and labelling, package, transport, and storage of fertilizer grade urea. It is applicable to urea in solid form, e.g. granular, prilled, or pastilled, which is made by the reaction of ammonia with carbon dioxide. Urea can be classified by its intended use, industrial and/or agricultural. It is mainly used as fertilizer in the field of agriculture. It is only applicable to fertilizer grade urea in the field of agriculture.

ISO 18644:2016 specifies the requirements for testing methods, sampling and preparation of test sample, marking and labelling, as well as package, transport, and storage of controlled-release fertilizer. ISO 18644:2016 is applicable to controlled-release products having one or more primary fertilizer nutrient (nitrogen and/or phosphorous and/or potassium) in a controlled-release form. They can be made by bulk blending (BB) fertilizers or by special processes.

ISO 18645:2016 specifies the requirements for testing methods, sampling and preparation of test sample, marking and labelling, as well as package, transport, and storage of water soluble fertilizers. ISO 18645:2016 is applicable to water soluble fertilizers which are completely soluble in water and are suitable for fertigation and sprinkling irrigation, as well as for foliar application (foliar feeding).

ISO 18643:2016 specifies the test procedure for determination of the biuret content in liquid and solid urea-based fertilizers based on the HPLC method.