CONICET | Buscador de Institutos y Recursos Humanos

Estimations indicate that there will be nearly 10 billion people on Earth by 2050. Then agriculture will be required to generate about 50% more food because of the rise in the world population (FAO, 2017). The great challenge for agricultural systems is to provide secure food for the growing world population while maintaining or improving soil and water quality, together with working towards the mitigation of climate change without exceeding planetary boundaries (Wanyenze et al., 2023). This can be achieved through sustainable agriculture intensification and involves increasing current levels of production while minimizing impacts on the environment.Nitrogen (N) availability is one of the most crucial factors that limit plant growth and development, both in natural ecosystems and in agronomic systems where nitrogen is mainly provided as fertilizer. However, its use is limited by the high cost of production and the toxicity of chemical fertilization. The massive use of nitrogen fertilizers had a strong positive impact on agricultural productivity. As a result, the global demand for nitrogen fertilizers has steadily increased. Unfortunately, on the other hand, higher N inputs are associated with higher N surpluses, which are in turn often linked to negative environmental consequences if not incorporated in soil organic matter, contributing to greenhouse gas emissions (N2O), ozone depletion (NO), and water pollution (NO3-). Furthermore, N volatilization (NH3) may contribute to eutrophication of neighboring systems. N management must therefore play a central role in the sustainable transformation facing global food production (Ying et al., 2017; Leip et al., 2021). This implies that alternative strategies should be applied to maximize the availability of agronomic resources and optimize crop yields (Cassman and Dobermann, 2021; Leip et al., 2021)N fertilizers are a primary global N source to agroecosystems but have a large CO2 footprint. The second largest source of supplying N to agroecosystems is biological nitrogen fixation (BNF) driven by a symbiotic relationship between legumes and soil bacteria collectively known as rhizobia. The symbiotic relationship between soil rhizobia and legumes generates root nodules where rhizobia uses plant photosynthates to convert atmospheric N2 into NH3 through their nitrogenase enzyme, providing this biologically useful nitrogen to the plant. The N2-fixing capacity benefits not only legume plants themselves but also other coexisting species in mixed pastures or intercropped crops, as well as subsequent crops, thus reducing the need for synthetic N fertilizers. The biochemical, genetic, and evolutionary aspects of the symbiotic interaction have been extensively reviewed over the years (Jones et al., 2007; MacLean et al., 2007; Oldroyd and Downie, 2008; Gibson et al., 2008; Masson-Boivin et al., 2009; Downie 2010; Oldroyd et al., 2011; Hawkins and Oresnik, 2021). Improving the effectiveness of the BNF process has been the focus of research for many decades. It is a current major goal within the sustainable use of soils, which is one of the worldwide challenges of the time. This Research Topic complements/extends the previous Volume I (Isarri et al., 2021), addressing different approaches directed toward the exploitation of the symbiosis between legumes and rhizobia as a helpful tool to develop more sustainable agricultural systems. The understanding of the BNF process will increase our capacity to design sustainable diversified agroecosystems through the inclusion of legumes.

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