Organic manures in relation to rhizosphere effect

Abstract

Summary Application of ammonium sulphate (AS) + rock phosphate (RP) and farm yard manure (FYM), after green manuring stimulated the growth of phosphate (PO 4 ) solubilizing organisms in the rhizosphere soils of rice at early tillering stage. Except under AS + RP, the count increased with time with the age of the crop at final harvest, being highest with FYM, followed by rice straw (RS) + AS and AS alone. Residually all the manures, except AS + RP, enhanced the number of the PO 4 -solubilizers in the rhizosphere of wheat only at final harvest. Green manuring (control) incited the growth of PO 4 -solubilizing Mycobacterium which was further stimulated with RS + RP together with Bacillus . AS + RP incited Streptomyces and Aspergillus , RS + AS Streptomyces , and AS alone Penicillium in the rhizosphere of rice. Residually, the manures stimulated the cited microflora, excepting Mycobacterium , in the rhizosphere of wheat. Phosphate-solubilizing power of the rhizosphere soils increased with AS + RP, RS + AS, and town compost (TC). The power increased with the age of the crop, being highest with AS + RP, followed by RS + RP, TC, and RS + AS. Excepting TC, other residual manures improved the PO 4 — solubilizing power of the rhizosphere soils of wheat, being highest with FYM, followed by RS + AS, AS + RP, RS + RP, and AS alone. In general, rhizosphere effect of wheat under the residual influence was superior to that of rice under the direct influence of the manures. PO 4 -solubilizing power was not always correlated with the population of the responsible organisms in the rhizosphere.