## 4 Conclusions  
This manuscript presents detailed results of tests of the usefulness of two types of diffractometers, i.e., Analysette 22 and Helos, for determining the grain composition of the full spectrum of organic soils and draws the following conclusions:  
* In the group of low-organic soils (sample No. 1, 2), the conclusions are not clear, because the soil results of sample No. 1 did not show any significant similarity between the laser methods and the reference method, whereas in the case of No. 2, an apparent similarity was observed between the laser diffractometer method results, which also differed significantly from the reference method. * In the group of medium-organic soils (sample Nos. 3-7), there was, in most cases, some, sometimes even high, agreement between the test results performed using both laser diffractometers, but they were not comparable with the results of the reference method. * In the group of high-organic soils (sample Nos. 8-12), we found exceptional agreement of the test results between the hydrometric method and the Analysette 22 laser diffractometer in almost all cases. When analyzing the above conclusions, it should be borne in mind that the results obtained may be influenced not only by the quantity, but also by the type of substances and the type of connection of the materials constituting the mineral-organic aggregate. Unfortunately, this requires a comprehensive physico-chemical study, which is beyond the scope of this work. The tests also showed that the dispersion method can also affect the results obtained, and the capabilities of a specific diffractometer may also have an impact on the obtained results. A fully reliable, alternative reference method is also lacking. However, these limitations do not diminish the research potential of laser diffraction methods, whose main value lies in the speed and repeatability of the test and the minimally simplified procedure for preparing samples for testing, which effectively eliminates errors associated with the human factor. In conclusion, the authors believe that the laser diffractometer method, if reliably verified, could be an effective tool for determining the grain composition of a material with an extremely complex skeleton structure, such as organic soils, for which classical or standard testing methods are not fully effective. Conceptualization, G.S. and M.S. ; methodology, G.S. and M.S. ; formal analysis, G.S. and M.S. ; investigation, G.S. and M.S. ; resources, G.S. ; data curation, G.S. and M.S. ; writing--original draft preparation, G.S. and M.S. ; writing--review and editing, G.S. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. The raw data supporting the conclusions of this article will be made available by the authors on request. The authors are grateful to the Atest Ltd. company representative of Sympatec GmbH (Clausthal-Zellerfeld, Germany) for their help in the particle size tests with the use of a HELOS laser diffractometer. The authors declare no conflicts of interest. * [PERSON] and [PERSON] (2020) [PERSON]; [PERSON] Estimating the Unit Weight of Local Organic Soils from Laboratory Tests Using Artificial Neural Networks. _Appl. Sci._**2020**, _10_, 2261. [CrossRef]
* [PERSON] and [PERSON] (2021) [PERSON]; [PERSON] Evaluation of the Unit Weight of Organic Soils from a CPTM Using an Artificial Neural Networks. _Arch. Circ. Eng._**2021**, _67_, 259-281. [CrossRef]
* [PERSON] et al. (2024) [PERSON]; [PERSON]; [PERSON]; [PERSON] Convolutional neural network-based model for recognizing TBM rock chip gradation. _Autom. Contr._**2024**, _163_, 105414. [CrossRef]
* [PERSON] and [PERSON] (2011) [PERSON]; [PERSON] A Neural Network-Based Soft Sensor for Particle Size Distribution Using Image Analysis. _Powder Technol._**2011**, _212_, 359-366. [CrossRef]
* [PERSON] (2022) [PERSON] The Effect of Methodology on Determining the Liquid Limits Values of Selected Organic Soils. _Arch. Circ. Eng._**2022**, _68_, 459-477.