Nitrogen fixation and crop productivity enhancements codriven by intercrop root exudates and key rhizosphere bacteria

1. Crop diversity management is widely used to increase agricultural productivity and sustainability. Recent studies have demonstrated that maize root exudates can drive interspecific facilitation to enhance N2 fixation of bean in intercropping systems. However, the mechanisms of N2 fixation enhancement stimulated by root exudates in the intercropping systems remain unclear. 2. Four experiments were designed to provide a progressively deeper understanding of how root exudates stimulate microbial-mediated N2 fixation. First, the effects of faba bean/maize intercropping on yields and soil microbial communities were determined in a field experiment. Second, root-derived interspecific facilitation was evaluated using a root partitioning approach. Third, the key microbial taxa in the faba bean rhizosphere were traced using 13C-labeled maize root exudates. Fourth, the codriven mechanism of maize root exudates and microorganisms in the faba bean rhizosphere were explored. 3. Faba bean/ma...