Effect of different levels of nitrogen and phosphorus on atmospheric nitrogen fixation and computation by various methods in four species of Acacia

摘要

Greenhouse study was carried out on sandy clay loam soil (Typic Haplustalf) of Coimbatore, Tamil Nadu to determine the amount of nitrogen fixed from the atmosphere by different species of Acacia by various methods by the application of nitrogenous and phosphatic fertilizers ill combination with N_2 fixing organisms. The accuracy of various methods of N_2 fixation were evaluated and the results predicted that 'A' value technique was comparatively best suitable method for tree crops closely followed by dilution method. Among the four Acacia species, A. nilotica derived maximum amount of nitrogen from the atmosphere followed by A. planifrons due to the application of ~(15)N urea (75%)+ SSP (100%)+ Rhizobium + VAM.