2021 journal article

Root influences on soil bulk density measurements with thermo-time domain reflectometry

GEODERMA, 403.

By: Y. Fu n , Y. Lu *, J. Heitman n  & T. Ren *

co-author countries: China πŸ‡¨πŸ‡³ United States of America πŸ‡ΊπŸ‡Έ
author keywords: Root zone; Bulk density; Spatial and temporal dynamics; Root water content; Root density
Source: Web Of Science
Added: July 26, 2021

β€’ Root influences on soil bulk density measurements with thermo-TDR technique are quantified. β€’ The extended de Vires heat capacity model is used to account for the root effects. β€’ A critical root density that affects thermo-TDR measurements is determined. The thermo-TDR (time domain reflectometry) technique has been applied for measuring soil bulk density (ρ b ) in-situ. However, the accuracy of thermo-TDR measured ρ b data, as influenced by plant roots, has not been studied. In this study, we applied the extended de Vries heat capacity model to examine the influences of roots on thermo-TDR sensor performance for measuring ρ b dynamics in the root zone. Soil samples were collected at multiple depths and horizontal positions over time during a maize growth period, and ρ b values were determined gravimetrically and indirectly from thermo-TDR measurements. Results showed that by using the extended de Vries model, the thermo-TDR measured ρ b agreed well with the gravimetric values. Ignoring root contribution to bulk soil heat capacity introduced 6.7%, 13.8% and 13.9% errors in thermo-TDR measured ρ b data on the loamy sand, sandy loam, and clay loam soils, respectively. A critical root density of 0.037 g cm βˆ’3 was determined beyond which roots may induce ρ b errors greater than 0.1 g cm βˆ’3 with the thermo-TDR technique.