Determination of particle size distribution in soils: comparison of results obtained by the hydrometer vs. the pipette method
1987
Matar, A. | Garabed, S. (ICARDA, Aleppo (Syria)) | Harmsen, K. (Institut voor Bodemvruchtbaarheid, RA Haren (Netherlands))
Ninety four soil samples were collected from the main agricultural areas of Syria and subjected to analysis by pipette and hydrometer methods. The samples represented different soil depths from irrigated and rainfed soils, collected from low, medium, and high rainfall areas. Calcium carbonate content in the soils ranged from 2% to 47%, the clay content from 4% to 85%, and organic matter from 0.32% to 2.33%. The results from the two methods of analysis highly correlated (R=0.83), although the hydrometer readings after 2h (H2) indicated higher values for clay content than did the pipette method. The differences occurred because the hydrometer readings represented all soil particles with diameter less than 3.88+0.12 (microns) mu, whereas the clay fraction is represented by particles 2 (microns) mu in diameter. From these readings, correction factor was derived better results: % clay (pipette) = -13.787+1.136x(H2). The hydrometer readings taken after 7 hours (H7) provided a closer fit with results from the pipette methods (R=0.87) because they r0842epresented all soil particles with diameter less than 2.1+0.07 (microns) mu. The regression equation was: % clay (pipette) = -1.213+1.090x(H7). Hydrometer readings at 4 hours (H4) were found to be highly correlated with the 7-hours readings (R=0.97) and provided a closer fit with the pipette method than did 2-hours readings: % clay (pipette method) = -0.955+1.062x(H4). Thus, the hydrometer method, with readings taken at 4 hours, could be used as an alternative for the pipette method to determine clay content for all practical purp
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