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Effect of Acidithiobacillus on solubilization of natural phosphate in a coastal tableland soil under yam bean (Pachyrhizus erosus) crop

A greenhouse experiment was carried out to evaluate the effect of sulphur (S) inoculated with Acidithiobacillus on phosphorus (P) availability from natural phosphate (NP) using different fertilizer application methods on yam bean (Pachyrhizus erosus) grown in a "Tableland Forest" soil (Podzol Hydromorphic dystrophic) of the "Zona da Mata" in the State of Pernambuco, Brazil. Plants were inoculated with rhizobia strains (NFN 747 and NFB 748) and control treatments added without rhizobia inoculation. The P treatments were: (1) NP pelleted with S inoculated with Acidithiobacillus (NP S*); (2) S with Acidithiobacillus pelleted with NP (S* NP); (3) NP and S mixture inoculated with Acidithiobacillus (S* + NP); (4) NP and S mixture without Acidithiobacillus (NP + S); (5) triple superphosphate (TS) fertilization and (6) control treatment without phosphorus application (P0). The fertilizers were applied: a) on the surface; b) in the plant furrow 10 cm below the seeds; c) in the furrow 10 cm below and beside the seeds. Nodule dry matter was higher with (NP + S*), and best results were obtained when fertilizers were applied beside and above seeds. The treatment (FN + S*) increased plant height, dry biomass of nodules, tubers, and shoots, and the total N uptake, especially when applied 10 cm below seeds. Total P uptake was highest with (S* NP) applied 10 cm below seeds. The available soil P was highest in the treatments (NP + S*) and (NP + S) with most evident results when applied 10 cm below seeds.

biofertilizers; reactive phosphate; Gafsa; fertilizer placement


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