Early tree-soil-root relationships of Prosopis, Eucalyptus, and Azadirachta planted on sodic soils

Tree-soil-root relationship were studied in a field trial of a native (Azadirachta indica), and two exotic (Eucalyptus tereticornis and Prosopis juliflora) multipurpose tree species planted on a sodic soil in India. The calcic pan of the planting hole was penetrated with mechanical augers. Root systems of twelve three-year-old trees were excavated, and above- and below-ground biomass, and nutrient concentrations in tree components were examined. Compared to other species, Peosopis exhibited the earliest canopy closure, accumulated the highest above- and below-ground biomass, and partitioned the greatest carbon to shoots while maintaining relatively constant root: shoot ratio. Prosopis developed the maximum fine-root and total-root biomass, root spread and root depth, as well as a capacity to egress into sodic soil and penetrate the kankar pan. Nutrient accumulation was highest for Prosopis , achieved with stable nutrient balance, and effective Na exclusion from metabolically sensitive parts such as leaves. The Na was confined to older storage components such as stem and branches. The superior growing strategy by Prosopis suggests that this species is most suited for sodic soil amelioration and that tree root systems contribute significantly to sodicity alleviation.