environmental sample from soil metagenome
six treatments were replicated three times as following: (1) Inoculation with P. stutzeri A1501 by dipping the corn seedling roots in suspension cells (containing 8 × 108 cells/ml), before planting in nature soil. (2) Corns seedlings were directly plated in nature soil with no P. stutzeri A1501 inoculation. Besides, two compartments of soil (surface soil and rhizospheric soil) were collected. Thus, a total of 24 samples (2 inoculation treatments × 2 water conditions × 2 soil compartments × 3 replications) were established for nifH pyrosequecing analysis at 60-day of maize.