Caracteristicas agronômicas da soja submetidas à inoculção e adubação com torta de nim

Abstract

In Brazil, soy stands out in agribusiness due to the use of technologies, such as inoculation with bacteria for nitrogen fixation. Coinoculation is a technique that improves seed quality and increases productivity. Furthermore, the addition of neem cake as a supplementary fertilizer is explored for its fertilizing properties. The objective of this study was to evaluate the impacts of inoculation and coinoculation with beneficial bacteria, associated or not with the addition of neem cake, on the agronomic characteristics of soybean crops in the municipality of Areia-PB. A randomized block design was used with six treatments and four replications, totaling 24 plots. The treatments were as follows: (T1 – Bradyrhizobium; T2 – Azospirillum; T3 – Bradyrhizobium + Azospirillum; T4 – Bradyrhizobium + neem pie; T5 – Azospirillum + neem pie and T6 – Bradyrhizobium + Azospirillum + neem pie). Two inoculants were used, the first, composed of the bacteria Bradyrhizobium japonicum strains 5079 and 5080 in peat format, at a dosage of 120g/50kg of seeds. As it is an area of first cultivation, the dose applied was twice that recommended. The second inoculant used, composed of the bacteria Azospirillum brasilense and Pseudomonas flourescens, was applied in liquid form at a dosage of 150 mL.ha-1. The neem cake was applied in two stages (VC and V4), using a 20-liter knapsack sprayer. Harvesting was carried out manually when 97% of the pods presented a color typical of physiological maturity (stage R8), that is, when the pods reached a brown color. Several variables were evaluated, including plant height, insertion height of the first pod, number of pods per plant, weight of pods per plant, weight of a thousand grains and productivity. The results showed that the association of Bradyrhizobium with neem cake promoted the highest productivity, while the combination of Azospirillum and neem cake resulted in the lowest productivity. The use of neem cake positively influenced the productivity of soybeans inoculated with Bradyrhizobium compared to other treatments. Water deficiency during the crop cycle probably had a negative impact on the agronomic characteristics of the crop, contributing to low average productivity. The appropriate choice of inoculants and complementary fertilizers to optimize soybean crop productivity is extremely important, especially when facing adverse conditions.