A Simple field volumetric method for estimating soil bulk density and three-phase composition

초록

Soil bulk density and three-phase composition are critical physical indicators for evaluating soil health and supporting sustainable soil management. In-situ measurement of these properties helps diagnose field-related constraints affecting productivity, such as poor drainage, compaction, aeration, and drought stress. While the oven-dry gravimetric method (OG) is the standard for measuring these parameters, its application in the field is constrained by time and equipment requirements. To address this, a simple field volumetric method (FV) was developed and validated through comparative analysis with the OG method. Both methods were applied to 38 soil samples to measure bulk density and three-phase composition (solid, liquid, and gaseous). Agreement was assessed using linear regression, coefficient of variation (CV), Bland–Altman plots, and Cronbach’s alpha. Regression results showed significant (P < 0.01) correlations between methods, with r2 values of 0.89 - 0.91 and standard errors ranging from 0.05 to 3.92. The solid phase showed the highest compatibility among the three-phase composition. CVs ranged from 4.7 - 17.3 for FV and 3.5 - 15.2 for OG, but differences were not statistically significant. Most values fell within the 95% limits of agreement in Bland–Altman analysis. Cronbach’s alpha values higher than 0.7 (0.95 - 0.97) indicated excellent internal consistency across parameters. These findings demonstrate that the FV method provides a reliable and efficient alternative for rapid field assessment of soil bulk density and three-phase composition.

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