About this Research Topic
The 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. This can be achieved through sustainable agriculture intensification and involves increasing current levels of production while minimizing impacts on the environment.
Nitrogen is an essential nutrient for plant growth and development. The intensification of agricultural systems typically implies greater use of nitrogen to increase yields. As a result, the global demand for nitrogen fertilizers has been rising steadily. Unfortunately, higher nitrogen use is directly linked to negative environmental consequences. The efficiency of nitrogen fertilizer use by crops and forages is relatively low (30-50%), and a large part of nitrogen inputs, if not incorporated in soil organic matter, may end up being released into the environment. Consequently, this contributes to greenhouse gas emissions (N2O), ozone depletion (NO), water pollution (NO3-), or volatilization (NH3). On the other hand, the synthesis of chemical fertilizers is energy-intensive and thus has a large carbon footprint.
Leguminous crops have the ability to fix N from the atmosphere. The symbiotic relationship between soil bacteria, collectively known as rhizobia and legumes, generates root nodules where rhizobia use plant photosynthate to convert atmospheric N2 to a plant-usable form through their nitrogenase enzyme. This benefits not only the legumes themselves but also other coexisting species in mixed pastures, or intercropped or subsequent crops, thus reducing the need for N fertilizers. Improving the effectiveness of the biological nitrogen fixation (BNF) process has been the focus of much research and is a current major goal within the sustainable use of soils, in itself being one of the global challenges of the century. This Research Topic aims at gathering current, state-of-the-art research on the improvement of legume-rhizobia symbiosis and its effect on both productivity and the economic-environmental sustainability of agroecosystems.
The Research Topic will include studies on grain and forage crops, leguminous plants used as cover crops, green manures, or those in rotations with other crops. It will consider:
(i) New methodologies (e.g. quantification of nitrogen fixation, rhizobia inoculation techniques)
(ii) Selection of rhizobia strains for efficiency and competitive ability
(iii) The effects of environmental factors on symbiosis performance, specifically including plant-soil feedbacks and the synergy and trade-offs of multi-bioinputs formulations on BNF
(iv) Improvements of the symbiosis efficiency by specific plant-host associations
(v) Approaches to incorporate BNF into non-legume crops
This Topic will be dedicated to the memory of Tomás Ruiz-Argüeso (1943-2020) in recognition for a lifetime of research on the improvement of symbiotic biological nitrogen fixation in legumes.
Keywords: rhizobia, inoculants, nitrogen fixation, legumes, environmental sustainability
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.