Biological nitrogen fixation for fertilizer-limited crop production

点击翻译按钮获取中文摘要

Organic agriculture is a rapidly expanding market in Canada, and it is growing faster than the non-organic sector. Canada is the sixth-largest organic consumer market, and in 2020, Canadian consumers bought more than $7 billion worth of organic food. There were more than 7,500 organic operations in Canada in 2019, accounting for roughly 2% of total agricultural land, and the demand for organic food outstrips current production capacity. The yield gap of organic compared to conventional agriculture is a major challenge and is primarily attributed to the prohibition of synthetic Nitrogen fertilizer. Farmers have been creative with outsourced natural fertilizers such as manure, organic residues, and compost, but these are costly. The inoculation of crops with N2-fixing bacteria such as those from the genus Azospirillum is an efficient and low-cost alternative to increase the input of N to organic crops. These bacteria not only fix atmospheric nitrogen to the plants, but also produce plant growth promoting molecules (phytohormones, vitamins, secondary metabolites), siderophores, and organic acids that solubilize phosphates in the soil, promoting root growth and plant health and resilience. N2-fixing bacteria have been studied for years, and although they are widely commercialized in South America, their use in North America is still rare. The few Azospirillum products that are available for use in North America commonly originate from South America, and their effects on Canadian crops are often inconsistent due to incompatibilities with Canadian conditions and soils. Isolating and characterizing Azospirillum strains and other N2-fixing isolates from Canadian soils and developing microbial inoculant products that are suitable for Canadian crops will increase yield and reduce input costs. We propose the isolation and characterization of N2-fixing bacteria from Canadian soils and the development of inoculants based on these isolates for improvement of N levels in Canadian organic cropping systems. The major outcome will be to increase the production of organic crops to supply the demand for organic food products while contributing to environmental sustainability.