The symbiotic relationship between cover crops and soil microorganisms is closely linked to nutrient cycling and crop growth within agroecosystems. However, how cover crops with different root functional traits influence soil microbial communities, soil properties, and crop yields has remained understudied. This study assessed the root traits of hairy vetch (HV) and rapeseed (RP), along with soil properties, sweet potato yield, and microbial enzyme activity under red soil dryland conditions. High-throughput sequencing was also employed to characterize the diversity, composition, and network structure of soil bacterial and fungal communities. According to the plant economic spectrum theory and our research results on plant root traits, HV can be identified as a resource-acquisitive cover crop, and RP treatment can be identified as a resource-conservative cover crop. Although RP treatment did not significantly increase the sweet potato yield, the increase rate reached 8.49%. Resource-conservative cover crops were associated with increased pH, SOC, and TP, which enhanced bacterial species diversity and boosted the populations of Chloroflexi and Alphaproteobacteria. In contrast, resource-acquisitive cover crops promoted the proliferation of Gammaproteobacteria. Network analysis indicated that resource-conservative cover crops facilitated network complexity through intensified intra-community competition. Resource-acquisitive cover crops enhanced the stability of microbial communities. Collectively, these findings underscore the distinct advantages of cover crops with varying root functional traits in shaping soil microbial communities. Appropriate cover crop rotations can effectively regulate microbial communities and hold the potential to enhance crop yield.

The determination of an optimal nitrogen (N) fertilization rate is critical for the sustainable large-scale cultivation of Cinnamomum camphora var. linaloolifera for essential oil production. Both suboptimal and excessive nitrogen inputs can adversely affect plant sustainable development and essential oil biosynthesis, underscoring the necessity of precise nutrient management. This study investigated the effects of five N application rates (0, 45, 90, 135, and 180 kg·hm⁻²) on vegetative growth, essential oil yield, and quality. Growth parameters, including plant height, basal diameter, specific leaf area (SLA), and essential oil yield and yield rate. Oil composition was characterized via gas chromatography–mass spectrometry (GC-MS). The application of 90 kg·hm⁻² N significantly enhanced plant height (74.31%), basal diameter (54.95%), SLA (20.91%), and biomass (181.8%) relative to the nitrogen-free control. Nitrogen uptake was concentrated in foliar tissues, accounting for 82.8% of total plant nitrogen accumulation. This fertilization rate also maximized essential oil yield (9.15 g·plant⁻¹) and yield rate (2.44%), reflecting increases of 178.9% and 24.49%, respectively. Linalool was the predominant oil constituent (89.84–91.81%), with its highest concentration observed at the 90 kg·hm⁻² treatment. At this rate, the relative abundance of oxygenated compounds increased by 0.97%, while hydrocarbon content decreased by 0.62%, indicating a qualitative improvement in oil composition. The findings reveal a threshold response to nitrogen input, wherein rates exceeding 90 kg·hm⁻² did not confer further benefits and may reduce efficiency. Collectively, these results suggest that a nitrogen application rate of 90 kg·hm⁻² optimally enhances vegetative growth, nitrogen assimilation, and both the quantitative and qualitative traits of essential oils in C. camphora var. linaloolifera.

Arbuscular mycorrhizal fungi (AMF) demonstrate considerable potential for remediating soils contaminated with heavy metals. However, comprehensive research examining the effects of cadmium (Cd) contamination on AMF communities in paddy fields remains scarce, constraining their broader application in such environments. In this study, high-throughput sequencing was utilized to assess AMF community structure in paddy soils subjected to five distinct levels of Cd contamination. The study also explored the effect of different soil properties on AMF community dynamics. A total of 188 AMF taxa were identified across all soil samples, spanning four families. The Claroideoglomeraceae family emerged as the predominant group, exhibiting notable Cd tolerance. While elevated Cd concentrations inhibited the AMF community structure, lower concentrations increased the α-diversity of the community. Furthermore, soil-available phosphorus, calcium levels, and pH were found to be critical factors driving shifts in AMF community structure. Redundancy analysis explicitly quantified the relative strength of environmental factors, demonstrating that phosphorus and pH directly influenced the AMF community structure through significant effects, while Cd and calcium exerted their influence via indirect or nonlinear pathways. Given the relative abundance advantage of Claroideoglomeraceae in Cd-contaminated environments and its positive correlation with Cd concentration, we hypothesize that this group may exhibit Cd tolerance. Therefore, it could be considered a potential candidate species for prioritization in future field inoculation trials, and its practical application potential should be further validated.