Interaction of tree crops with a sodic soil environment: potential for rehabilitation of degraded environments

Abstract

Tree species of Acacia nilotica, Dalbergia sissoo, Prosopis juliflora and Terminalia arjuna were grown on sodic land for a decade at the Biomass Research Centre, Banthra (of National Botanical Research Institute, Lucknow) India (80°45′–53′E and 26°40′–45′N) with the objective of discovering their relationship with the sodic soil environment to rehabilitate it for maximum fuelwood production. Results showed a marked improvement in biogeochemical characteristics of soil by increasing the water holding capacity (WHC), and by the addition of organic carbon, nutrients and fungal microflora. It was found that D. sissoo and P. juliflora were more efficient than were A. nilotica and T. arjuna in rehabilitating the land. Litter production by the first two was greater than that provided by A. nilotica and T. arjuna, which subsequently caused depletion in soil pH and exchangeable sodium percentage (ESP) values. It was found that there was a greater circulation of Ca, Mg and Fe than the other nutrients by all four tree species, which was a desirable factor. Microbial activity was enhanced due to the accumulation of humus through decomposition of leaf litter and root decay. The potential extent of the biological rejuvenation of the sodic land was related to the distribution of tree roots in the soil profile. To obtain better results a combination of such tree species should be selected in order to provide maximum and constant litter mulch throughout the year. This, in turn, would protect the land from desiccation. Thus, sodic lands could be rehabilitated effectively to restore degraded environments through appropriate mixed tree cropping systems. © 1998 John Wiley & Sons, Ltd.