🌱 Air-dry and dry matter of plant material for agricultural chemical analysis — two gravimetric methods: air-dry matter in fresh material (natural or artificial drying at no more than 60 °C with forced air circulation) and dry matter in air-dry material (105 ± 2 °C for 3 h to constant mass), with dry matter recalculated to fresh material; PN-R-04013:1988 (withdrawn standard)

Environment PN-R-04013

Overview

WHAT THE STANDARD COVERS. The "Scope" field of the PKN card, in full: "Two methods are laid down. The method for determining air-dry matter in fresh plant material consists in drying the sample to the air-dry state naturally or artificially at a temperature not exceeding 60 degrees Celsius with forced air circulation. The method for determining dry matter in air-dry plant material consists in drying the sample at a temperature of 105+-2 degrees Celsius for 3 h until constant mass is reached. The preparation of the laboratory sample is given. The calculation of dry matter in fresh plant material is specified" (our translation; spelling as on the card, no full stop at the end). We did not have the text of the standard (4 pages).

STATUS (card as of 13.10.2026). The card of PN-R-04013:1988 (Polish version) bears the heading "Withdrawn": publication 09-03-1988, "Withdrawal date: 01-09-2014", 4 pages, price group B, Food, Agriculture and Forestry Sector, KT 90 Soil Cultivation and Horticulture, ICS 65.020.20; there are no "Replaces" or "Replaced by" fields. The PKN search under "PN-R-04013" (12.10.2026) returns only this standard; among the first 50 results for "powietrznie suchej" (air-dry, 13.10.2026) the only standard on plant material is this one — the others concern, among others, butter, milk, cheese, yoghurt, ice cream, tea, latex and soil. We do not name any standard that would have replaced it for the dry matter of plants.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database from the production server, refreshed on 12.10.2026). Number 04013 appears in 9 records at 9 laboratories; in the current PCA documents (read on 12–13.10.2026; issues from 24.06.2025 — AB 333 — to 22.07.2026 — AB 317) — in 9 rows at the same laboratories; a search of all downloaded PCA documents found no laboratories outside the database copy, no row with the number is set in bold italics, and no pages are repeated in any document. Notations: "PN-R-04013:1988" — 5 laboratories (AB 277, AB 312, AB 787, AB 1172 — "excluding point 3.4" — and AB 1186); "PN-88/R-04013" — 4 (AB 317, AB 333, AB 789, AB 921). The "Laboratories" tab looks for notations BEGINNING with the search term: for "PN-R-04013" it shows 5 laboratories, and for "PN-88/R-04013" — 4 — checked with the tab query on the labcoda.pl production server on 13.10.2026; this page searches with "PN-R-04013", so the tab shows 5 of the 9 laboratories.

WHAT THE LABORATORIES TEST (database copy and PCA documents). Test object: plant material — all 9. Characteristic and range: dry matter content — AB 277 (0.01–99.9 %), AB 312 (0.10–99.9 %), AB 787 (10.0–98.0 %), AB 789 (80.0–99.9 %), AB 921 (10.0–99.0 %), AB 1172 (10.0–99.9 %); dry matter and air-dry matter content — AB 317 (0.1–99.9 %), AB 1186 (5.00–99.9 %); separately air-dry matter (5.00–40.00 %) and dry matter (70.00–100.00 %) — AB 333. Technique: gravimetric method — all. In the same documents, next to dry matter there are entries for determining constituents of plant material according to in-house procedures (including total nitrogen, phosphorus, calcium, magnesium, metals).

ALONGSIDE THIS STANDARD. No other document stands in the entries with this standard (apart from the exclusion of point 3.4 at AB 1172). We do not know the content of point 3.4.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — basis of the result: the standard distinguishes fresh material, air-dry material and dry matter (card), and the result "dry matter content" means something different for fresh material and for air-dry material; only AB 333 separates air-dry matter (5.00–40.00 %) and dry matter (70.00–100.00 %) in its scope, the others give a single range (from 0.01–99.9 % at AB 277 to 80.0–99.9 % at AB 789) without saying to which material it refers — this has to be stated in the report. Second — two temperatures: air-dry matter is dried at no more than 60 °C with forced air circulation (or naturally), dry matter at 105 ± 2 °C for 3 h to constant mass; these are two different quantities that cannot be substituted for each other. Third — status: the standard has been withdrawn since 01.09.2014 without a successor being named, and all 9 laboratories have it in their scopes. Fourth — tab: because of the two notations of the number, the "Laboratories" tab of this page shows 5 of the 9 laboratories.

WHAT WE DO NOT GIVE. We did not have the text of the standard — we do not give the sample mass, the grinding and preparation of the laboratory sample, the air-drying time, the calculation formulae, precision or the content of point 3.4.

Method principle

Two gravimetric methods (PKN card): air-dry matter in fresh plant material is determined by drying the sample to the air-dry state naturally or artificially at no more than 60 °C with forced air circulation; dry matter in air-dry material by drying the sample at 105 ± 2 °C for 3 h to constant mass; dry matter in fresh material is calculated from both determinations. WE DO NOT GIVE the formulae or details — we did not have the text of the standard.

Applications

• Agricultural chemical analysis of plants — air-dry matter of fresh material and dry matter of air-dry material (PKN card)
• Calculation of dry matter in fresh plant material (PKN card)
• Plant material — in the current accreditation scopes of 9 laboratories, all by the gravimetric method

Key parameters

Standard

Standard number

PN-R-04013:1988

Title (PL)

Analiza chemiczno-rolnicza roślin — Oznaczanie powietrznie suchej i suchej masy

Title (EN)

Agricultural chemical analysis of plants — Determination of air-dry and dry matter

Step-by-step procedure

1. Laboratory sample

   Preparation of the laboratory sample — described in the standard according to the card; WE DO NOT GIVE details. PN-R-04013:1988 withdrawn on 01-09-2014 (card as of 13.10.2026).

2. Air-dry matter

   Fresh material is dried to the air-dry state naturally or artificially at no more than 60 °C with forced air circulation (PKN card).

3. Dry matter

   Air-dry material is dried at 105 ± 2 °C for 3 h to constant mass (PKN card).

4. Calculation

   Dry matter in fresh plant material from both determinations (PKN card); WE DO NOT GIVE the formula. In the report — to which material the result refers.

Required equipment and apparatus

Health and safety (OHS)

• Drying ovens at 60 °C and 105 °C — hot vessels, heat-resistant gloves
• SUBJECT-MATTER NOTE: standard withdrawn in 2014 without a successor being named; "dry matter" without stating the material (fresh or air-dry) is ambiguous

Frequently asked questions