Scope of using phosphate solubilizing microorganisms (Bacillus subtilis and Aspergillus niger) for P-transformation in tea soil

Abstract

Low phosphorus content of acidic tea soils is due to significant amount of iron and aluminum oxides hindering growth and yield of tea (Camellia sinensis L). Phosphate solubilizing microorganisms (PSMs) increase available P in acid soils. For the present investigation, eleven treatments were imposed in young tea (CV. TV23) through two years pot experiments using complete randomized design (CRD) with three replications using surface soils (0-15 cm depth) collected from Tocklai Tea Estate. Objectives of present investigation were to evaluate soil P dynamics and tea plant response to the PSM, viz. phosphate solubilizing bacteria (PSB, viz. Bacillus subtilis) and fungus (PSF, viz. Aspergillus niger) determining alternative to the traditional phosphatic fertilizers. A field study was also conducted to evaluate tea plant response to the PSMs. Results from the fractionation study indicated that PSM influences dissolution of insoluble P irrespective of treatment imposed. Combined application of 50% of recommended doses of phosphate (RDP) and 20L A. niger (or 20 kg Bacillus subtilis) resulted in significantly higher build up of available P and the highest green leaf yield. PSF performed better than PSB. Field study revealed that integrated treatments increased soil available phosphate over RDP that showed non-significant increase in yield of tea over 100% RDP. From the results it was concluded that application of 50% of RDP along with PSM can be considered as promising fertilization strategies for tea cultivation in P deficient acid soil in Assam, India.