Abstract
The production of mineral fertilizers is a expensive process, since it requires high energy consumption, and cannot be produced by small farmers. Laboratory assays were conducted to produce P-biofertilizers from natural phosphate (B5, B10, B15, B20), applying sulphur at different rates (5; 10; 15 and 20%) inoculated with Acidithiobacillus (S*) and testing increasing periods of incubation. A greenhouse experiment was carried out to evaluate the effect of the biofertilizers in a soil with low available P (Typic Fragiudult) from the "Zona da Mata" of Pernambuco State, grown with yam bean (Pachyrhizus erosus) in two consecutive harvests. The treatments were: Natural Phosphate (NP); biofertilizers produced in laboratory (B5, B10, B15, B20) with sulphur and Acidithiobacillus (NP+S*); natural phosphate with sulphur (20%) without Acidithiobacillus (NP+S); triple super phosphate (TSP) and a control without phosphorus. Plants were inoculated with a mixture of rhizobia strains (NFB 747 and NFB 748) or did not receive rhizobia inoculation. In bioassays pH and available P in the biofertilizers were analyzed. In the greenhouse experiment shoot dry matter, total N and total P in shoots, soil pH and available P were determined. Higher rates of available P were obtained in biofertilizers with sulphur and Acidithiobacillus (NP+S*) and in triple super phosphate (TSP), and biofertilizers with sulphur and Acidithiobacillus (FN+S*) and triple super phosphate (TSP) increased plant parameters. Native rhizobia were as effective as the strains applied in inoculation. After the two harvests soil presented lower pH values and higher rates of available P when the biofertilizers B15 and B20 with sulphur and Acidithiobacillus were applied.
Highlights
The treatments were: Natural Phosphate (NP); biofertilizers produced in laboratory (B, B, B, B ) with sulphur and Acidithiobacillus (NP+S*); natural phosphate with sulphur (20%) without Ac5idit1h0iob1a5 cil2l0us (NP+S); triple super phosphate (TSP) and a control without phosphorus
The botanical and genetic characteristics of yam bean have been studied by the International Yam bean Program in Denmark and researches with rhizobia effectiveness and response to fertilizers are realized in Brazil by the Nucleus of Biologic Nitrogen Fixation in the Tropics (NFBNT) at the Federal Rural University of Pernambuco
The results obtained in trays incubated for 60 days were inferior to available P in assays with Petri dishes, the biofertilizers produced from natural phosphate and sulphur inoculated with Acidithiobacillus showed potential in phosphorus availability (Table 1)
Summary
The results obtained in trays incubated for 60 days were inferior to available P in assays with Petri dishes, the biofertilizers produced from natural phosphate and sulphur inoculated with Acidithiobacillus showed potential in phosphorus availability (Table 1). Greenhouse experiment Shoot dry matter of yam bean in the two harvests were not different under fertilization with either natural phosphate with sulphur and Acidithiobacillus (NP+S*) or triple super phosphate (TSP), which showed higher dry biomass of shoots compared to the others P treatments (Table 2).
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