Regular Article

Plant and Soil

, Volume 332, Issue 1, pp 163-176

First online:

Dynamics of soil water content in the rhizosphere

  • Andrea CarminatiAffiliated withHelmholtz Centre for Environmental Research—UFZ Email author 
  • , Ahmad B. MoradiAffiliated withHelmholtz Centre for Environmental Research—UFZ
  • , Doris VetterleinAffiliated withHelmholtz Centre for Environmental Research—UFZ
  • , Peter VontobelAffiliated withPaul Scherrer Institute—PSI
  • , Eberhard LehmannAffiliated withPaul Scherrer Institute—PSI
  • , Ulrich WellerAffiliated withHelmholtz Centre for Environmental Research—UFZ
  • , Hans-Jörg VogelAffiliated withHelmholtz Centre for Environmental Research—UFZ
  • , Sascha E. OswaldAffiliated withHelmholtz Centre for Environmental Research—UFZ

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

Water flow from soil to plants depends on the properties of the soil next to roots, the rhizosphere. Although several studies showed that the rhizosphere has different properties than the bulk soil, effects of the rhizosphere on root water uptake are commonly neglected. To investigate the rhizosphere’s properties we used neutron radiography to image water content distributions in soil samples planted with lupins during drying and subsequent rewetting. During drying, the water content in the rhizosphere was 0.05 larger than in the bulk soil. Immediately after rewetting, the picture reversed and the rhizosphere remained markedly dry. During the following days the water content of the rhizosphere increased and after 60 h it exceeded that of the bulk soil. The rhizosphere’s thickness was approximately 1.5 mm. Based on the observed dynamics, we derived the distinct, hysteretic and time-dependent water retention curve of the rhizosphere. Our hypothesis is that the rhizosphere’s water retention curve was determined by mucilage exuded by roots. The rhizosphere properties reduce water depletion around roots and weaken the drop of water potential towards roots, therefore favoring water uptake under dry conditions, as demonstrated by means of analytical calculation of water flow to a single root.

Keywords

Root water uptake Water retention curve Rhizosphere Neutron radiography Mucilage Hysteresis