On the potential impact of root system size and density on salt distribution in the root zone

Abstract

Soil salinization in agricultural environments is a major soil degradation process, particularly in dry regions. Soil salinization puts at risk the natural ecosystem and the agricultural crops, which are usually sensitive to elevated salinities. In this work, a conceptual model is proposed and tested experimentally, to examine the impact of root system dimension and distribution on solute transport and accumulation in the root zone. For this purpose, tomatoes were grown in growing chambers, under conditions of salty water irrigation. Root density, salt concentration and soil water content distributions were measured and correlations between the three parameters were found for different root system sizes. Results show that confined root systems were highly salinized with a strong correlation between root location and salt distribution in the soil. Broad root systems, on the other hand, showed a reduction in soil bulk salinity at the root zone and that about 50 % of the root system is under conditions of low salinity. The physical reasons for this observation are proposed herein and it is suggested that in the future, development of crops with large root systems could be considered as another tool to cope with soil salinization.