Workpackage number 5: Soil water balance model Start date or start event: 0
Activity Type: RTD/Innovation
Participant ID

UPCT 

INRA 

Person-month per participant

16 

92


Objectives

  1. Development and validation of a soil water balance model taking into account (i) the spatial heterogeneity of the soil, water distribution and root system and (ii) the soil-plant feedbacks.
  2. Assessment of the impact of water supply and soil water variability on the root system architecture.
  3.  Elaboration of a simplified framework for the soil-plant water exchanges.

Description of work

(Task 5.1) Development of a simplified model of the water transfer in soil under various irrigation regimes and implementation of this soil model into the crop models (months 1-12).

After the acquisition of primary and elaborated field data on water uptake, soil water distribution and root system development and location under different irrigation modalities, the main objective of WP5 is to study the soil-root system water relations by means of a 3D mechanistic modelling framework that takes explicitly into account the water dynamics in the soil and within the root system. From this mechanistic model, we will derive and evaluate the effective root sink term, using only a few plant and soil parameters. The effective root sink for water will be incorporated into the crop model, therefore accounting for the effects of heterogeneous soil water distribution and, most particularly, the use of different localized irrigation systems, on plant performances and fruit quality.

(Task 5.2) Development of a detailed model of root water uptake using a plant architectural approach and root–soil feedback (months: 1-24).

In the second task, the root system architecture (i.e. the framework for the soil plant-plant exchanges) and its variations with water distribution and variability will be studied. Under conditions of soil water deficit, the whole tree functioning is modified in multiple ways and at different time scales. At the root system level, roots located in zones with higher water availability exhibit large growth leading to growth compensation for the other parts of the root system. At the single root level, the morphogenetic processes of root system elaboration could be modified, specially the root ramification. Therefore, the global and local response of the root system architecture, a key point of plant water uptake, will be investigated, in response to various irrigation practices. Specific experimentation in the case of peach will be carried out and the modelling framework linking the root architecture to water availability distribution within the soil will be developed. Root system architecture and its variations with the heterogeneity of water availability will be the input of the 3D water uptake model, integrating water transfer in the soil and in the plant.

WP5 will be developed by the UPCT and INRA teams, using the data recorded in the different orchards and pilot farms, available from the orchard database (WP1). The expected results (Soil-water balance model and root water uptake model, Month 12 and 24 respectively) will be of paramount importance for the prediction of soil water status and the interpretation of soil-based indicators measurements. Both models will be further integrated into the global crop model.


Deliverables:

D9: Development of a simplified soil-water balance model under different irrigation conditions (month 12)

D27: Root water uptake model. Prediction of the effects of irrigation practices (month 24)


Milestonesand expected result:

Milestones: M5.1.Month 12 The availability of a simplified soil-water balance model is of paramount importance for the prediction of the soil water status and the interpretation of soil-based indicators measurements. M5.2.Month 24. The root water uptake model should be ready for its further integration into the global crop model (WP6)

Results: The results and models obtained in this WP will be the basis for optimizing the location of the sensors, as well as for the design of the irrigation system (emitters location, agronomic design, hardware and software components).