Biomass production and changes in soil productivity during longterm cultivation of Prosopis juliflora (Swartz) DC inoculated with VA mycorrhiza and Rhizobium spp. in a semi-arid wasteland

The growth of Prosopis juliflora and its contribution to soil enrichment following inoculation with three vesicular-arbuscular isolates, Glomus caledonius, Gigaspora calospora, and an indigenous strain, and two Rhizobium isolates, P-5 and Tal-600, were assessed. The trees were 6 years old and grew on a semi-arid wasteland. There was a significant increase in the biomass of closely spaced P. juliflora inoculated with G. caledonius alone. P. juliflora, growing on a relatively nutrient-deficient wasteland, significantly restored the soil productivity by ameliorating and enriching the soil. A significant reduction in the soil reaction (pH) and a considerable improvement in soil organic carbon build-up and phosphorus, at both depths, were observed in all the treatments by the end of the experiment. Moreover, although the total nitrogen content increased in comparison to controls, this increase was not statistically significant when comparisons were made between respective treatments at the beginning of the experiment and after 6 years‘ growth. Received: 5 February 1997