DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 11-12/2013 str. 16 <-- 16 --> PDF |
The purpose of this research was to establish whether there was a difference in the results of PSD determination between the old method and the ISO 11277 Standard in the overall number of samples and particularly in the topsoil. Another goal was to test the difference in the textural interpretation of PSD results obtained by these two methods. For the needs of the analysis, 67 forest soil samples were taken from two areas in Croatia. The two methods were compared in order to determine whether there was a statistically significant difference in the total number of the samples. A comparison was also made to determine whether there was a statistically significant difference between the samples taken from the topsoil layer, since according to ISO 11277 the organic matter largely found in the surface soil part oxidizes. Statistical analysis and t-test revealed no statistically significant difference in any single fraction from the topsoil layer between the old method and ISO 11277. A high correlation was found in the topsoil layer for all the measured fractions (r = 0.98 for coarse sand, r = 0.96 fine sand, r = 0.94 coarse silt, r = 0.84 fine silt and r = 0.97 clay) as well as in the all established samples (r = 0.99 for coarse sand, r = 0.97 fine sand, r = 0.89 coarse silt, r = 0.88 fine silt and r = 0.97 clay). Based on the classification into three main fractions (sand, silt and clay) a higher percentage of sand and a lower percentage of silt was established by the old method compared with ISO 11277. This difference is directly reflected on textural interpretation. No statistically significant difference between the two methods was found for the clay fraction. Key words: particle size distribution, soil texture, Na-pyrophosphate, Na-hexametaphosphate, ISO 11277 |