27 Apr 2022
27 Apr 2022

Dynamic root growth in response to depth-varying soil moisture availability: a rhizobox study

Debora Cynthia Maan, Marie-Claire ten Veldhuis, and Bas Johannes Henricus van de Wiel Debora Cynthia Maan et al.
  • Geoscience and Remote Sensing, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands

Abstract. Plant roots are highly adaptable, but their adaptability is not included in crop and land surface models. They rely on a simplified representation of root growth, independent of soil moisture availability. Data of subsurface processes and interactions, needed for model set-up and validation, are scarce. Here we investigated soil moisture driven root growth. To this end we installed subsurface drip lines and small soil moisture sensors (0.2 L measurement volume) inside rhizoboxes (45 x 45 x 10 cm). The development of the vertical soil moisture and root growth profiles are tracked with a high spatial and temporal resolution. The results confirm that root growth is predominantly driven by vertical soil moisture distribution, while influencing soil moisture at the same time. Besides support for the functional relationship between the soil moisture and the root density growth rate, the experiments suggest that vertical root extension only takes place if the soil moisture exceeds a threshold value at the root tip. We show that even a parsimonious one-dimensional water balance model, driven by the measured water input and output fluxes, can be convincingly improved by implementing root growth driven by soil moisture availability.

Debora Cynthia Maan et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-104', Anonymous Referee #1, 21 May 2022
    • AC1: 'Reply on RC1', Cynthia Maan, 21 Jul 2022
  • RC2: 'Comment on egusphere-2022-104', Anonymous Referee #2, 28 May 2022
    • AC2: 'Reply on RC2', Cynthia Maan, 21 Jul 2022
  • RC3: 'Review of egusphere-2022-104', Stan Schymanski, 31 May 2022
    • AC3: 'Reply on RC3', Cynthia Maan, 22 Jul 2022

Debora Cynthia Maan et al.

Debora Cynthia Maan et al.


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Short summary
Their flexible growth provides the plants with a strong ability to adapt and develop resilience to droughts and climate change. But this adaptability is badly included in crop- and climate models. To model plant development in changing environments, we need to include the survival strategies of plants. Based on experimental data, we set up a simple model for soil moisture driven root growth. The model performance suggests that soil moisture is a key parameter determining root growth.