Biochar-based organic fertilizer application promotes the alleviation of tobacco (Nicotiana tabacum L.) continuous cropping obstacles by improving soil chemical properties and microbial community structure.

Abstract

Background: Intensive monoculture poses a serious threat to agricultural sustainable development due to the phenomenon of continuous cropping obstacles. Although organic amendment has been considered an efficient and environmentally friendly solution to mitigate this tough issue, the associated mechanisms remain poorly understood. Here, a two-year field experiment was conducted with the application of four fertilizers, wood, rice straw, compound biochar-based organic fertilizers (WBF, RBF, CBF) and chemical fertilizer (CF) under tobacco rotation with broad bean and oilseed rape, respectively. This work aims to determine how BFs application alleviates tobacco CCO and to further reveal the underlying action mechanisms primarily focusing on the change of soil micro-ecology environments.

Results: The results depicted that BFs addition decreased tobacco morbidity (by 15.7-85.0%), heavy metals (Cd, V, Cu, Zn) contents in tobacco, and improved tobacco leaf production yield (by 4.5-20.5%), economic value (by 14.6-34.4%) and chemical quality compared with CF. Rhizosphere soil chemical properties and the structure and diversity of microbial communities were enhanced under BFs treatments, reflecting in the growth of bacterial OTUs number, microbial alpha-diversity, the abundances of some beneficial genera (Arthrobacter, Pseudomonas, Gemmatimonas, Trichoderma, Mortierella, Penicillium, Chaetomium, etc.), and the reduction of the numbers of detrimental microbes (Alternaria, Phytophthora nicotianae and Fusarium oxysporum). Moreover, CBF amendment improved the stability and complexity of microbial co-occurrence networks. Soil total carbon, microbial structure, and diversity were the most important explanatory factors for the increase of tobacco leaf yield and economic value.

Conclusions: Collectively, BFs application under rotation regime showed the great potential as a practical and environmentally friendly strategy to alleviate tobacco CCO by providing an optimized soil environment.