oSIST prEN 15961:2026

Overview

The oSIST prEN 15961:2026 standard, developed by the European Committee for Standardization (CEN), specifies a reliable method for the extraction of water-soluble calcium, magnesium, sodium, and sulfur (as sulfates) from inorganic fertilizers. This standardized procedure enables the preparation of a single extract suitable for determining these key nutrients efficiently. The method involves boiling the fertilizer sample in water under controlled conditions, ensuring consistent extraction results to support quality control and compliance in fertilizer production.

This updated draft standard supersedes EN 15961:2017 and eliminates references to specific EU regulations, reflecting current regulatory and technical advancements. It is applicable specifically to inorganic fertilizers, supporting enhanced nutrient analysis required by the fertilizer industry and regulatory bodies.

Key Topics

• Scope of Application
  The method targets inorganic fertilizers, addressing the extraction of four essential nutrients critical to soil fertility and crop growth: calcium (Ca), magnesium (Mg), sodium (Na), and sulfur (S) as sulfates (SO₄).

• Extraction Principle
  Extraction is performed by boiling a measured portion of fertilizer in distilled or demineralized water for 30 minutes, followed by cooling and filtration to obtain a clear solution for nutrient determination.

• Sample Preparation
  Although sampling is outside this standard’s scope, preparation per EN 1482-2 is essential to ensure representative and homogenous laboratory samples. Grinding the fertilizer sample is recommended to enhance testing accuracy.

• Test Procedure Details
  The procedure adjusts sample size according to sulfur and calcium content, with:

  • 5 g sample for fertilizers with ≤ 3% sulfur and ≤ 4% calcium.
  • 1 g sample for fertilizers exceeding these limits.

  Water used must have low electrical conductivity (< 0.5 mS/m at 25°C), ensuring purity for extraction.

• Laboratory Equipment Required
  Standard lab apparatus includes electric hot plates, beakers (600 ml), graduated flasks (500 ml), and specific low-magnesium content filter papers for filtration.

• Reporting Requirements
  The test report must document all relevant details such as sample identification, method version, sampling date and method, extraction date, and any anomalies or optional parameters impacting the results.

Applications

The oSIST prEN 15961:2026 method is vital for:

• Fertilizer Manufacturers
  Ensuring product quality by verifying water-soluble nutrient content, confirming nutrient availability, and meeting labeling and regulatory requirements.

• Agricultural Laboratories
  Providing standardized, reproducible extraction procedures for reliable nutrient assays critical for soil amendment recommendations.

• Regulatory Compliance
  Supporting adherence to fertilizer standards across Europe by facilitating consistent nutrient measurement aligned with CEN norms.

• Research and Development
  Enabling precise evaluation of inorganic fertilizer formulations to optimize nutrient bioavailability and environmental impact.

Related Standards

• EN 1482-1 & EN 1482-3: Address general sampling and sampling of static heaps, providing methodologies to supply representative fertilizer samples for laboratory analysis.

• EN 1482-2: Specifies sample preparation provisions to achieve uniform samples suitable for testing.

• EN 12944-1 & EN 12944-2: Offer vocabulary and terms relevant to fertilizers and liming materials, ensuring consistency and clarity across standards.

Summary

The oSIST prEN 15961:2026 standard is an essential tool for consistent extraction and analysis of key water-soluble nutrients in inorganic fertilizers. Adopting this method helps ensure accurate nutrient content measurement, supporting fertilizer quality assurance, regulatory compliance, and optimal agricultural productivity. This standard's clear procedures and reporting guidelines make it invaluable for fertilizer producers, testing labs, and regulatory bodies focused on nutrient management and fertilizer efficacy.