DIN EN 16357
Carbonate liming materials - Determination of reactivity - Automatic titration method with citric acid; German version EN 16357:2013
Carbonatische Kalke - Bestimmung der Reaktivität - Automatisches Titrationsverfahren mit Citronensäure; Deutsche Fassung EN 16357:2013
Overview
The European Standard has been prepared in CEN/TC 260 "Fertilizers and liming materials" (secretariat: DIN) through Working Group WG 3 "Liming materials" the chairmanship and secretariat are held by Germany, and with the active participation of German experts. The national Mirror Committee is Working Committee NA 057-03-02 AA "Düngemittel" ("Fertilizers") of the Food and Agricultural Products Standards Committee (NAL). Lime influences all essential processes in soil. Soil chemistry (nutrient availability), soil biology (microbial activity) and soil physics (stability and character of the soil structure) change depending on the pH value of the soil. Liming materials that are used as fertilizers shall therefore fulfil certain quality parameters in order to achieve the desired effect. Along with the minimum content of alkaline ingredients and fineness, the reactivity is an important quality determinant factor as a measure for the reactivity in soil. This document specifies a method for the determination of the reactivity of calcium carbonate and calcium magnesium carbonate liming materials. It assesses the speed and effectiveness of their neutralising potential by automatic titration with citric acid. The method is applicable only to liming materials with a maximum particle size of 6,3 mm, where the particle size is determined in accordance with DIN EN 12948. Limited decomposition of carbonates in a given time takes place. Titration under stable pH conditions (pH value: 4,5) with an automatic titration apparatus. The citric acid consumption during a given time (15 min) is a direct measure for the reaction of the liming materials being tested. The precision data were derived from an inter-laboratory test involving 16 participants carried out in the year 2010 and analysing a range of several liming materials including limestone, dolomitic limestone, magnesian limestone and chalk of varying fineness or presentation. The precision data is summarized in Table 1 of the standard. Moreover, the arrangement of the test apparatus is depicted graphically.
