Crop rotation is widely practiced to improve agricultural sustainability, yet its impact on microbial diversity remains unclear. We conduct a global meta-analysis of 2406 paired observations to examine the effects of crop rotation on microbial diversity based on high-throughput sequencing data. We show that crop rotation significantly increases bacterial Shannon diversity and species richness, but has no effect on bacterial beta diversity. In contrast, crop rotation significantly increases fungal beta diversity without affecting fungal Shannon diversity and species richness. Changes in microbial communities are linked to soil pH, and available nitrogen and phosphorus. Notably, legume vs. non-legume, arbuscular mycorrhiza vs. non- arbuscular mycorrhiza, C3 vs. C4, and annual vs. perennial crop transitions, as well as climate and soil factors, affect the response ratios of microbial metics to crop rotation. Furthermore, the response ratios of bacterial Shannon diversity, bacterial species richness, and fungal species richness are positively related to the response ratio of crop yield. Our study reveals positive but differential effects of crop rotation on bacterial and fungal diversities, which are linked to improved crop productivity. Our findings thus have implications for using crop rotation to conserve soil microbial biodiversity, which is related to soil health and function, and enhance global food security.

Climate change is known to significantly affect vegetation development in the terrestrial system. Because Southwest China (SW) is affected by westerly winds and the South and East Asian monsoon, its climates are complex and changeable, and the time lag effect of the vegetation’s response to the climate has been rarely considered, making it difficult to establish a link between the SW region’s climate variables and changes in vegetation growth rate. This study revealed the characteristics of the time lag reaction and the phased changes in the response of vegetation to climate change across the entire SW and the typical climate type core area (CA) using the moving average method and multiple linear model based on the climatic information of CRU TS v. 4.02 from 1982 to 2017 together with the annual maximum (P₁₀₀), upper quarter quantile (P₇₅), median (P₅₀), lower quarter quantile (P₂₅), minimum (P₅), and mean (Mean) from GIMMS NDVI. Generally, under the single and combined effects of temperature and precipitation, taking the time lag effect (annual and interannual delay effect) into account significantly improved the average prediction rates of temperature and precipitation, which increased by 18.48% and 25.32%, respectively. The optimal time delay was 0–4 months when the annual delay was taken into consideration, but it differed when considering the interannual delay, and the delaying effect of precipitation was more significant than that of temperature. Additionally, the response intensity of vegetation to temperature, precipitation, and their interaction was significantly more robust when the annual delay was taken into account than when it was not (p < 0.05), with corresponding multiple correlation coefficients of 0.87 and 0.91, respectively. However, the degree of response to the combined effect of individual effects and climate factors tended to decrease regardless of whether time delay effects were taken into account. A more comprehensive analysis of the effects of climate change on vegetation development dynamics suggested that the best period for synthesizing NDVI annual values might be the P₂₅ period. Our study could provide a new theoretical framework for analyzing, predicting, and evaluating the dynamic response of vegetation growth to climate change.

Forestlands are widely distributed in the dominantly agricultural landscape in western Canada, and they play important ecological functions; such forestlands (e.g., shelterbelts) accumulate soil organic matter and may receive a substantial amount of nitrogen in the form of surface and subsurface runoff from adjacent croplands and become a significant source of emissions of greenhouse gases (GHGs) such as CO₂, N₂O, and CH₄. Biochar and nitrapyrin applications could potentially mitigate GHG emissions, but their co-application in forest soils has not been studied. We investigated the effect of the application of biochars produced at low (300 °C; BC300) and high temperatures (700 °C; BC700) using canola (Brassica napus L.) straw and the effect of their co-application with nitrapyrin on GHG emissions and soil properties in a 35-day laboratory incubation experiment using forest soils collected from five shelterbelt sites. Results showed no significant interaction effect of biochar and nitrapyrin on the global warming potential (GWP) of the GHG emissions, and the GWP was 15.8% lower in the soil with nitrapyrin than without nitrapyrin application treatments. The GWP was significantly enhanced by BC300 addition due to a 26.9% and 627.1% increase in cumulative CO₂ and N₂O emissions, respectively, over the 35-day incubation. The GWP significantly decreased by BC700 addition due to a 27.1% decrease in cumulative CO₂ emissions. However, biochar addition did not affect CH₄ emissions, while nitrapyrin decreased CH₄ uptake by 50.5%. With BC300 addition, soil-dissolved organic carbon and microbial biomass carbon increased by 26.5% and 33.9%, respectively, as compared to no biochar addition (CK). Soil pH increased by 0.16 and 0.37 units after the addition of BC300 and BC700, respectively. Overall, the effect of biochar and nitrapyrin was independent in mitigating GHG emissions and was related to the type of biochar applied and changes in soil properties.

In the background of climate warming, the demand for improving soil quality and carbon (C) sequestration is increasing. The application of biochar to soil has been considered as a method for mitigating climate change and enhancing soil fertility. However, it is uncertain whether the effects of biochar application on C-mineralization and N transformation are influenced by the presence or absence of plant growth-promoting bacteria (PGPB) and soil nitrogen (N) level. An incubation study was conducted to investigate whether the effects of biochar application (0 %, 1 %, 2 % and 4 % of soil mass) on soil respiration, N status, and microbial attributes were altered by the presence or absence of PGPB (i.e., Sphingobium yanoikuyae BJ1) under two soil N levels (N0 and N1 soils as created by the addition of 0 and 0.2 g kg^-1 urea- N, respectively). The results showed that biochar, BJ1 strain and their interactive effects on cumulative CO₂ emissions were not significant in N0 soils, while the effects of biochar on the cumulative CO₂ emissions were dependent on the presence or absence of BJ1 in N1 soils. In N1 soils, applying biochar at 2 % and 4 % increased the cumulative CO₂ emissions by 141.0 % and 166.9 %, respectively, when BJ1 was absent. However, applying biochar did not affect CO₂ emissions when BJ1 was present. In addition, the presence of BJ1 generally increased ammonium contents in N0 soils, but decreased nitrate contents in N1 soils relative to the absence of BJ1, which indicates that the combination of biochar and BJ1 is beneficial to play the N fixation function of BJ1 in N0 soils. Our results highlight that biochar addition influences not only soil C mineralization but also soil available N, and the direction and magnitude of these effects are highly dependent on the presence of PGPB and the soil N level.