🌿 Determination of pH in an aqueous suspension of soil improvers and growing media — sample prepared according to EN 13040, portion equivalent to 60 ml (20 mm sieve) or 250 ml (40 mm sieve) of sample volume weighed on the basis of bulk density, extraction with grade 2 water at a ratio of 1 : 5 for 1 h at (22 ± 3) °C, measurement with a pH meter with glass electrode in the settling suspension after calibration with at least two buffers, PN-EN 13037

Environment PN-EN 13037

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in the iTeh sample of SIST EN 13037:2012 (text of EN 13037:2011, English): in full — from the title page through the contents, foreword and Clauses 1–10 to Annex A (results of an interlaboratory trial) on page 7 inclusive. Outside the sample remains only the bibliography.

ACCORDING TO THE TEXT OF EN 13037:2011. The standard was prepared by CEN/TC 223 “Soil improvers and growing media” (secretariat ASI); it superseded EN 13037:1999, the main change being the change of the scope. Scope (1): instrumental method for the routine determination of pH in a suspension of soil improvers or growing media; not applicable to liming materials or preformed materials such as mineral wool slabs and foam slabs; the requirements of the standard may differ from national legal requirements for the declaration of these products. Normative references (2): EN 13040:2007 (sample preparation, dry matter, moisture content, laboratory compacted bulk density), EN ISO 3696 (water for analytical use), ISO 1770 (thermometers). Terms (3): according to EN 13040:2007. Principle (4): the sample is extracted with water at (22 ± 3,0) °C at a ratio of 1 : 5 (1 volume of sample + 5 volumes of water) and the pH of the suspension is measured with a pH meter. Reagents (5): water with a conductivity not higher than 0,2 mS/m at 25 °C and pH > 5,6 (grade 2 according to EN ISO 3696); buffer pH 4,00 at 20 °C — 10,21 g potassium hydrogen phthalate in 1000 ml; buffer pH 7,00 at 20 °C — 3,800 g potassium dihydrogen phosphate (dried 2 h at 110–120 °C) and 3,415 g disodium hydrogen phosphate in 1000 ml; buffer pH 9,22 at 20 °C — 3,800 g disodium tetraborate decahydrate in 1000 ml; commercial buffers (e.g. tablets) permitted; buffers are stable for one month in polyethylene bottles in a refrigerator; tetraborate stored for a long time may lose water of crystallization. Apparatus (6): pH meter with slope adjustment and temperature control, analytical balance with scale interval 0,01 g, glass and reference electrode or combined electrode (at pH above 10 — an electrode designed for that range; in systems containing soil the risk of electrode contamination increases), thermometer to the nearest 1 °C type C according to ISO 1770, plastic or glass containers accommodating sample, extractant and 10 % air volume, shaker keeping the sample in suspension without damaging its structure. Preparation (7): the sample is prepared according to EN 13040 and the laboratory compacted bulk density determined according to Annex A of EN 13040:2007; sample passing a 20 mm sieve — mass equivalent to 60 ml of sample volume to the nearest 1 g and 300 ml water; passing a 40 mm sieve — mass equivalent to 250 ml and 1250 ml water; in both cases shaking for 1 h at (22 ± 3) °C. Procedure (8): calibration of the pH meter according to the manufacturer’s manual with at least two buffers appropriate to the pH of the sample (with electrodes in good condition equilibrium is normally reached within 30 s); measurement of the suspension temperature — buffers and suspensions shall not differ by more than 1 °C; the suspension is agitated thoroughly just before measurement and the pH measured in the settling suspension; reading after stabilization, i.e. when the reading does not change by more than 0,1 pH over 15 s; values to one decimal place. Precision (9): repeatability and reproducibility for separately prepared samples should be in accordance with Table A.1 (trial according to ISO 5725); the values may not apply to other matrices. Report (10): reference to the standard, sample identification, result to 0,1 pH, operations not specified or optional and influencing factors, laboratory compacted bulk density. Annex A: interlaboratory trial of 1995, 16 laboratories, no outliers; unfertilized peat with perlite — mean pH 5,34, sr 0,04, r 0,12, sR 0,17, R 0,48; composted coarse bark — 6,43, sr 0,06, r 0,18, sR 0,35, R 0,99; composted straw and domestic sewage — 6,71, sr 0,03, r 0,09, sR 0,16, R 0,46.

STATUS (as of 03.10.2026). The PKN search (term “PN-EN 13037”, 03.10.2026) shows PN-EN 13037:2011 (English version, “Introduces: EN 13037:2011 [IDT]”) without a withdrawal note and PN-EN 13037:2002 (Polish version) withdrawn and replaced by PN-EN 13037:2011; the result PN-C-13037:1951 is a different document. In the iTeh catalogue (read on 03.10.2026) EN 13037:2011 has the status “Published”, stage 90.93 (decision to confirm); the draft new edition FprEN 13037 is at stage 50.20 (formal vote) since 24.09.2026, and its card (status “Not Published”) gives 14.01.2027 as the publication date. Soil pH is described in separate entries on PN-ISO 10390 and PN-EN ISO 10390.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read on 03.10.2026). The number 13037 appears in 5 records at 5 laboratories: AB 006, AB 180, AB 339, AB 700, AB 1748. In the current PCA documents (read on 03.10.2026, issues from 18.02.2026 to 21.08.2026) the number appears in 5 rows — one at each; in each of the five documents the number of page markers equals the number of PDF pages, without repetitions. The form “PN-EN 13037:2011” (AB 006, AB 180, AB 1748; at AB 339 after procedure PB 037 issue III of 13.03.2025) and “PN-EN 13037” without year (AB 700, flexible scope “E”). None of these items is suspended; the AB 339 document has a footnote on suspension of part of the scope marked in bold italics, but the row with PN-EN 13037 is not so marked. The “Laboratories” tab (term “PN-EN 13037”) shows all 5 laboratories — checked with a tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). Plant cultivation aids: soil improvers and growing media (AB 006, AB 180, AB 339, AB 700, AB 1748 — at AB 180 only soil improvers, at AB 1748 only growing media), at AB 339 also growth stimulants (biostimulants) and natural, organic and organo-mineral fertilizers, at AB 700 digestate and organic fertilizers (compost). Characteristic: pH (at AB 1748 “pH in H2O”), potentiometric method. Ranges: (2,0–10,0) (AB 006, AB 1748), (1,0–12,0) (AB 180), 2,0–12,0 (AB 339).

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. With the ratio: 1 : 5 refers to sample volume, and the portion mass is calculated from the laboratory compacted bulk density according to EN 13040 (4, 7.1). With particle size: 60 ml + 300 ml for the 20 mm sieve, 250 ml + 1250 ml for the 40 mm sieve (7.1.2, 7.1.3). With temperature: extraction at (22 ± 3) °C, and buffers and suspension shall not differ by more than 1 °C (7.1, 8.2). With the reading: in the settling suspension, just after mixing, when the change does not exceed 0,1 pH in 15 s (8.2). With water: grade 2, conductivity ≤ 0,2 mS/m, pH > 5,6 (5.1). With the material: not for liming materials or mineral wool and foam slabs (1). With the electrode: above pH 10 an electrode for that range; contact with soil risks contamination (6.3). With the report: the bulk density must be stated (10).

WHAT WE DO NOT GIVE. We did not read the details of sample preparation and bulk density determination according to EN 13040. Nor do we give pH requirements for soil improvers and growing media from national regulations or Regulation (EU) 2019/1009.

Method principle

A portion of the sample equivalent to 60 ml (or 250 ml) of its volume, weighed on the basis of the laboratory compacted bulk density, is shaken for 1 h with five times its volume of grade 2 water at (22 ± 3) °C. The pH is measured in the settling suspension just after mixing with a pH meter with glass electrode, calibrated with at least two buffers whose temperature differs from the suspension by no more than 1 °C, and read to 0,1 pH after the reading has stabilized.

Applications

• Soil improvers and growing media — routine determination of pH (1)
• Compost, composted bark, peat-based growing media — materials of the interlaboratory trial (Annex A)
• Soil improvers, growing media, biostimulants, organic fertilizers and digestate — pH in the accreditation scopes of 5 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN 13037:2011

Title (PL)

Środki poprawiające glebę i podłoża uprawowe — Oznaczanie pH

Title (EN)

Soil improvers and growing media — Determination of pH

Step-by-step procedure

1. Sample preparation

   According to EN 13040; determination of the compacted bulk density (Annex A of EN 13040:2007) (7.1.1). PN-EN 13037:2011 without a withdrawal note (03.10.2026).

2. Extraction

   Mass equivalent to 60 ml of sample (20 mm sieve) + 300 ml water or 250 ml (40 mm sieve) + 1250 ml; shaking 1 h at (22 ± 3) °C (7.1.2, 7.1.3).

3. Calibration

   pH meter according to the manual, at least two buffers appropriate to the sample pH (8.1).

4. Measurement

   Suspension temperature within ±1 °C of the buffers; mixing just before measurement; reading in the settling suspension when the change is ≤ 0,1 pH in 15 s (8.2).

5. Result

   pH to 0,1; in the report sample identification and bulk density (10).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Composts and materials with sewage — biological material; gloves and hand hygiene
• Disodium tetraborate and phosphates — avoid dusting and skin contact

Frequently asked questions