Inoculação, adubação nitrogenada e revestimento calcário em três variedades de soja ( Glycine max (L.) Merril)

TLDR: In the three experiments the variety Mamouth showed better nodulation than the other two varieties, the nodulation being less affected by the treatments, including inoculation, which shows varying dependence of nodulation upon environmental effects in the different varieties.

Abstract: Three field experiments were conducted in consecutive years at different areas utilizing a 3 x 3 x 3 factorial design consisting of three varieties, three nitrogen treatments (0, inoculation and mineral nitrogen) and three lime treatments (0, lime pelleting and liming the soil) with the objectives of studying the interference of mineral nitrogen and liming on nitrogen fixation and yield of different varieties of soybeans. In the three experiments the variety Mamouth showed better nodulation than the other two varieties, the nodulation being less affected by the treatments, including inoculation. The variety Pelikan presented the poorest nodulation. The variety Abura, in one of the experiments, had as poor nodulation as the variety Pelikan while in another, in the inoculated plots it nodulated as well as the variety Mamouth. This shows varying dependence of nodulation upon environmental effects in the different varieties. Liming increased nodulation of soybeans only in one of the experiments although the pH of all three soils was acid (4,8; 5,8 and 5,4). In the same experiment lime pelleting of the seeds was more effective than liming. Lime pelleting in one other experiment had similar efficiency but only when the seeds were inoculated (interaction N x lime treatments.) In relation to soybean yield significant differences were only observed between varieties which follow the general pattern of nodulation, Mamouth and Abura being more productive than Pelikan. In two of the experiments the nitrogen treatments were also significant showing higher yields with inoculation than with mineral nitrogen in one, while in another, mineral nitrogen was more effective than inoculation. There was, in two of the experiments, a highly significant regression of soybean yield with nodule weight indicating that nitrogen fixation was the limiting factor of soybean production, when no nitrogen fertilizer was used.