A First Insight on the Interaction between Desiccation Cracking and Water Transfer in a Luvisol of Belgium

Njaka Ralaizafisoloarivony,Angélique Léonard,Dominique Toye,Robert Charlier,Benoît Mercatoris,Aurore Degré

doi:10.3390/soilsystems5040064

Njaka Ralaizafisoloarivony, Angélique Léonard + Show 4 more

Open Access

https://doi.org/10.3390/soilsystems5040064

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Journal: Soil Systems	Publication Date: Oct 18, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Gembloux Agro-Bio Tech, University of Liège

Abstract

The present paper presents the interactions between water retention/evaporation and cracking during the desiccation of intact and disturbed Belgian Luvisol. The disturbed (DS) and undisturbed (NDS) samples (reduced-tillage-residue-in (RTRI) and conventional-tillage-residue-out (CTRO)) were collected from an agricultural field in Gembloux, Wallonia, Belgium. The drying experiment took place in controlled laboratory conditions at 25 °C. Moisture content, soil suction and surface cracks were monitored with a precision balance, a tensiometer and a digital camera, respectively. The image processing and analysis were performed using PCAS® and ImageJ® software. The results showed that crack formation was initiated at a stronger negative suction and a lower water content (Wc) in DS > CTRO > RTRI. The suction and the crack propagation were positively correlated until 300 kPa for the DS and far beyond the wilting point for the NDS. For the NDS, the cracking accelerated after reaching the critical water content (~20% Wc) which arrived at the end of the plateau of evaporation (40 h after crack initiation). The Krischer curve revealed that the soil pore size > 50 µm, and that it is likely that cracks are important parameters for soil permeability. The soil structure and soil fibre content could influence the crack formation dynamic during drying. The agricultural tillage management also influences the crack propagation. As retention and conductivity functions are affected by cracks, it is likely that the movement of fluids in the soil will also be affected by the cracks following a desiccation period (i.e., when the cracked soil is rewetted).

Highlights

Crack propagation is an important natural phenomenon in agricultural fields, especially in fine-grained soils such as the Luvisol of Belgium [1,2]
The results show significant differences in the bulk density and the total porosity between the RTRI and the other treatments (i.e., CTRO and DS) at a 95% confidence level
The fibres from the RTRI were slightly shorter in individual length, narrower in width and lighter in weight compared to the CTRO (Figure 3)

Summary

Introduction

Crack propagation is an important natural phenomenon in agricultural fields, especially in fine-grained soils such as the Luvisol of Belgium [1,2]. Cracks may act as a bypass for water and solutes, lower the soil water content and increase its matric suction [3]. Cracks form when the tensile strength of the soil is reached during desiccation [5]. The physical (structure, porosity and aggregates) and chemical properties (pH, organic carbon, cations and anions) of soil are supposed to influence the crack formation/propagation [7]. These parameters are essentially affected by agricultural practices

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