Co-occurrence network of soil bacterial communities in agricultural fields in central Yunnan under different fertilization treatments

Abstract

Abstract Aims Soil microbial communities contribute to crops' growth, health, and productivity during agricultural production. However, how different fertilization practices affect the diversity, composition, and co-occurrence networks of soil bacterial communities during the different tobacco growth stages remains elusive. Methods Here, we report on the soil bacterial communities' alterations and their characteristics after fertilizer application at different tobacco growth stages and fallow periods. The experiments were performed in long-term continuous crop tobacco fields by applying different fertilizers (control (CK), cattle manure organic fertilizer (OM), cattle manure organic fertilizer chemical fertilizer mix (MNPK), chemical fertilizer (NPK), and crushed straw (ST)) at the time of tobacco planting. The soil bacterial communities were assessed using high-throughput sequencing technology and molecular ecological network methods. Results Soil bacterial diversity did not exhibit substantial alterations after fertilizer application during the growing period of roasted tobacco. The bacterial diversity was only increased in the fallow period, and the bacterial community composition was altered in the maturation and fallow periods. The bacterial community functions were mainly influenced by the roasted tobacco cultivation stage and did not exhibit substantial differences in response to fertilizer application. Bacterial interspecies relationships throughout the tobacco planting cycle were mainly cooperative. The co-occurrence networks were divided into four modules with the following network stability across the different growth periods: retardation period > maturation period > fallow period > fast growth period. The key taxa of the co-occurrence network were significantly decreased in abundance during tobacco cultivation's peak and maturity periods and gradually recovered after following. Fertilizer application significantly affected the bacterial co-occurrence network and thus influenced the bacterial community functions and enzyme activity, mainly by increasing soil nutrients (alkaline nitrogen and available phosphorus). Conclusion The application of straw, chemical fertilizer, and cow manure organic fertilizer mixed with chemical fertilizer resulted in the improved growth of roasted tobacco. On the other hand application of organic matter fertilizer (straw and cow manure) as a base fertilizer could reverse the bacterial co-occurrence network changes after the fallow period and improve the overall health of the tobacco-planted soil.