Root-induced changes in soil thermal and dielectric properties should not be ignored

Abstract

There is a lack of quantitative understandings on root-mediated changes of soil physical properties. Here we investigated the influences of maize roots on soil heat capacity (C), thermal conductivity (λ) and dielectric constant (ε) of the root zone. Root-zone soil cores were collected at different depths and horizontal positions from the eighth leaf to milk stage of maize, and C, λ and ε of the samples were measured with the thermo-TDR technique. Improved C, λ and ε models that included the influences of roots were developed and validated. The patterns and magnitudes of root effects on C, λ and ε generally followed the configurations of root distribution. On average, the presence of roots caused increases in soil C, λ and ε by 8.8%, 7.1% and 13.6%, respectively. For the root-zone soils, root influences on thermal properties and dielectric constant were significant and could be described quantitatively by using the proposed models.