Considering the main current limitations and potential of biological fixation of N2 (BNF) in soybean crop and benefits attributed to various crops by inoculation with Azospirillum brasilense (diazotrophic bacteria with free life), with emphasis on larger development of the root system and consequently greater absorption of water and nutrients, we can infer that co‐inoculation with both microorganisms of Bradyrhizobium sp. and A. brasilense can improve the crop performance in an approach that meets the current demands of agricultural, economic, and environmental sustainability. Thus, important researches are needed to evaluate the nutritional status, production components, and the soybean yield affected by cobalt and molybdenum application mode and co‐inoculating seeds with bradyrhizobia and A. brasilense. We found that seed inoculated with A. brasilense and application of cobalt and molybdenum provided higher N concentration in leaf and mass of 100 grains, with a positive impact on the grain yield of soybean, with an increase of 1007 kg ha‐1 of grain, equivalent to 18.4% more than the control (only inoculated with rhizobia). This research demonstrated that co‐inoculation with Bradyrhizobium sp. and A. brasilense associated with the application of cobalt and molybdenum is beneficial for nutrition and soybean yields.
Part of the book: Soybean
The management of nitrogen fertilization is performed in order to ensure adequate productivity, and depending on the N dynamics in the soil, large amount of N is added to the soil, raising production cost for the farmers. Considering the benefits attributed by seed inoculation with Azospirillum brasilense (diazotrophic bacteria), with emphasis on biological nitrogen fixation (BNF), greater development of the root system, and, consequently, greater absorption of water and nutrients, it infers that inoculation can improve crop performance allowing greater efficiency of nitrogen fertilization. Thus, the research that evaluates nutritional status and wheat yield, in terms of nitrogen rates in association with inoculation with A. brasilense is important. We found that increment of N rates in association with A. brasilense inoculation increases the wheat yield up to 139 kg ha−1 N, whereas without this inoculation linear increase occurred with lower maximum yield of wheat. That is, the inoculation afforded higher grain yield applying less nitrogen fertilizer in topdressing. This research demonstrated that inoculation with A. brasilense associated with nitrogen fertilization in topdressing is beneficial to nutrition and wheat yield. Therefore, inoculation is a low-cost technique, easy to apply and use, and nonpolluting, which fall within the desired sustainable context in actuality.
Part of the book: Wheat Improvement, Management and Utilization
The biological nitrogen fixation (BNF) process in wheat (Triticum aestivum L.) occurs by diazotrophic bacteria, particularly Azospirillum brasilense. However, researches are lacking on BNF efficiency to define how much mineral nitrogen (N) can be applied to achieve more sustainable high yields, and if urea with the urease enzyme inhibitor is less harmful, benefiting BNF in grasses (cereals). Therefore, the objective was to evaluate the effect of N sources (urea and Super N, urea with urease enzyme inhibitor N‐(n‐butyl thiophosphoric triamide) (NBPT) and N rates (0, 50, 100, 150, and 200 kg ha−1) applied in topdressing associated with inoculation with A. brasilense, regarding the leaf N concentration, leaf chlorophyll index (LCI), accumulation of N in the straw and grains, the nitrogen utilization efficiency (NUE), recovery of the applied nitrogen (RAN), physiological efficiency (FE), agronomic efficiency (AE), and wheat grain yield in the Brazilian Cerrado (tropical savanna) region. The N sources provide similar N accumulations in straw and grains, and wheat grain yield. Inoculation with A. brasilense afforded higher N grain concentration (increase in protein content more sustainably) by applying less N fertilizer in topdressing. Inoculation with A. brasilense increased the AE, RAN, and NUE.
Part of the book: Nitrogen in Agriculture