Manure fertilization enhanced microbial immigration in the wheat rhizosphere.

Purpose: Microbial immigration is essential for understanding microbial mechanisms involved in nutrient cycling under different fertilization strategies. Here, we aimed to illustrate the effects of fertilization on microbial immigration in the wheat rhizosphere. Materials and methods: Bacterial 16S rRNA gene and fungal ITS sequencing were applied to determine the microbial composition in the wheat rhizosphere. Co-occurrence networks, spatiotemporal source models, and structural equation models (SEMs) were conducted to investigate microbial immigration in two different niches (bulk soil and rhizosphere) and at two growth stages with different fertilization strategies (control without fertilization (CK), chemical fertilization (NPK), and organic manure fertilization (OM)). Results and discussion: OM greatly decreased the network complexity ratio of the rhizosphere to bulk soil for bacteria (CK/NPK/OM ratio: 4.14/1.65/0.64) and fungi (CK/NPK/OM ratio: 1.09/1.35/0.72). The proportion of bacterial and fungal communities in the rhizosphere sourcing from the bulk soil was highest under OM treatment (94.34%; 88.78%), followed by NPK (88.69%; 83.86%) and CK (85.30%; 76.40%) treatments. The jointing stage contributed more than the flowering stage to microbial immigration. In comparison to fungi, the proportion of bacteria in the rhizosphere derived from the bulk soil was much higher. Structural equation model indicated that the increase of total carbon under OM treatment affected the composition of bacteria and fungi by promoting microbial immigration from the bulk soil to the rhizosphere. Conclusions: OM treatment enhanced microbial immigration in the wheat rhizosphere, providing novel insights into plant-soil-microbiota interactions in the wheat rhizosphere. [ABSTRACT FROM AUTHOR]