Influence of root mass on saturated hydraulic conductivity in arid soils of central Tunisia

Abstract

Saturated hydraulic conductivity, K_fs,measured with the inversed auger hole method was related to root mass (living and dead roots) in the uppermost 30 cm of the soil. The studies were carried out in mountain, piedmont and plain areas. Acacia cyanophylla, Eucalyptus occidentals, Pinus halepensis, Atriplex numularia and Opuntia ficus‐indica as well as irrigated and non‐irrigated almond and olive orchards were included in the study. In older stands with well developed root systems, a significant positive linear relationship between K_fs and root mass was obtained. The regression coefficients, i.e., influence of root mass on K_fs, were generally higher in non‐aggregated than in aggregrated soil. In younger plantations (2–3 years old) the relationship was weaker and negative, probably owing to the lower proportion of dead roots and channels formed after root death. Measurements of K_fs with a double ring infiltrometer were compared to those obtained with the inversed auger hole method. Two‐to three‐fold higher values (regression coefficient of 2.47) were generated with the double ring infiltrometer method on non‐vegetated plots. On vegetated plots there was no correlation between the two methods. The inversed auger hole method seems to be promising and well suited for studies of the kind outlined in this paper. Further tests have to be made.