Enabling Biological Nitrogen Fixation for Cereal Crops in Fertilized Fields

Area of Science:

• Agricultural Science
• Microbiology
• Synthetic Biology

Background:

• Synthetic nitrogen fertilizers are crucial for agriculture but cause significant environmental pollution.
• Biological nitrogen fixation (BNF) is a natural process with potential to replace synthetic fertilizers.
• Current BNF applications are limited by fertilizer use and crop type.

Purpose of the Study:

• To develop and deploy a microbial product for BNF in corn (Zea mays) within fertilized agricultural fields.
• To demonstrate the potential of BNF to replace or reduce synthetic nitrogen fertilizer use.
• To achieve safe commercialization of root-associated diazotrophs.

Main Methods:

• Utilized synthetic biology tools to optimize a wild nitrogen-fixing microbe, Klebsiella variicola 137-1036 (Kv137-1036).
• Enhanced nitrogen fixation activity 122-fold in nitrogen-rich environments.
• Conducted multi-year, multi-site field trials across the U.S. Corn Belt.

Main Results:

• Kv137-1036 demonstrated successful colonization of corn roots and increased nitrogen fixation.
• Fields treated with Kv137-1036 showed higher yields (0.35 ± 0.092 t/ha) compared to synthetic nitrogen fertilizers alone.
• Within-field yield variance was reduced by 25% in 2018 and 8% in 2019.

Conclusions:

• A broad-acre BNF product (Kv137-1036) can reliably provide nitrogen for corn in field conditions.
• This microbial product offers significant agronomic benefits, including increased yield and reduced yield variability.
• The successful commercialization highlights the potential of synthetic biology to advance sustainable agriculture.