In January – February 2026, a ring test organized by EiraNet Grain Network took place. Both Latvian and Estonian companies participated in it. Some non-grain network labs/instruments also participated.
3 wheat and 3 rapeseed samples were offered in the ring test.
The reference results were obtained in the laboratory of SIA “Eira Lab”.
Comments:
Since ring test samples are in transit for a relatively long period, minor changes in moisture content are inevitable. Therefore, the reference laboratory determines the moisture level of the samples at both the beginning and the end of the ring test. The average of these two measurements is used as the reference value.
Moisture fluctuations also affect the test weight (bulk density) of the samples. Consequently, the same methodology has been applied to determine the reference values for test weight.
This year’s ring test shows a higher dispersion in test weight values compared to previous years. This is likely due to the specific characteristics of the 2025 harvest: unusually low test weights and poorer grain quality, which result in greater deviations in both positive and negative directions.
| Commodity | Parameter | Reference method | sR for stats evaluation |
|---|---|---|---|
| Wheat | EN ISO 712:2009 | 0,14% | |
| EN ISO 20483 | 0,20% | ||
| ISO 21415-1 | 0,70% | ||
| ISO 21415-2 | 0,70% | ||
| Master instrument results | 2,5 ml | ||
| Master instrument results | 0,94% | ||
| ISO 7971-3 | 0,29 kg/hl | ||
| Rapeseed | ISO 665:2000 | 0,16% | |
| ISO 659:2009 | 0,55% |
The “Parameter” column of the table contains links to the relevant results and graphs. The link will open in a new page, the results table is initially organized by lab code, but you can change the layout to your liking. For each sample, the difference to the reference value is given, as well as the statistical evaluation of this difference as a Z-factor. All results with Z-factors less than 2 are considered good. If Z>2 – it is colored yellow, if Z>3 – it is colored red. In these cases, it would be advisable to look for reasons why these results are different. The last column “Z-fact-Median (ABS)” is the median value of the Z-fact, which gives an approximate overall assessment of your laboratory. It has the same criteria as the Z-factor score. “sR” is the standard deviation of the reproducibility of the results, which we simply call “standard error”. Z-factor is a performance criterion for the participating laboratories (or instruments). It is calculated by dividing the difference (lab.res.-ref.res.) by the sR.
Protein values in dry matter were compared for Wheat, with a nitrogen factor of N=5.7.
For Wheat Gluten both values – ISO 21415-1 (manual method) and ISO 21415-2 (Glutomatic method) were compared.
The Starch values in dry matter were compared for Wheat.
For Wheat the Testweight values “As Is” were compared, the unit of measure – kg/hl.
Oil in dry matter values were compared for Canola.
Results submitted with a different moisture base and/or a different nitrogen factor or in other units were recalculated accordingly.