查看更多>>摘要：? 2021 Elsevier B.V.Soil of agro-ecosystems consists of complex biological interactions directly shaped by human activity, accounting for the overall soil quality. Bacterial communities are key players in most biogeochemical cycles. Here we investigated soil bacterial communities in four adjacent maize farming systems, conventional, transition, natural, and organic in order to study the effects of these practices on soil bacterial community, uncover most influential bacterial taxa and explore them as predictors of categorical and continuous soil variables (i.e. attributes). While richness and diversity were only marginally affected, we found pronounced farming system effects on bacterial community composition. The organic farming system exhibited higher bacterial community stability over two crop years. Conventional farming network exhibited the highest density and number of keystone taxa, however all keystone taxa were shared by one module only. Whilst organic farming presented the biggest and less dense network with the smallest number of keystone taxa. Blastocatellales was one of the most influential orders in organic and natural farming system networks. Bacterial taxa associated to the farming systems were visualized by a bipartite graph and used to build random forest models capable of predicting the farming system regardless of the crop year with high accuracy. The models were also able to predict soil chemical and biological attributes to a different extent. Altogether, we have shown that soil bacterial communities are deeply shaped by the underlying farming system, and can be used as a tool in sustainable farming monitoring.
查看更多>>摘要：? 2021Subsurface drip irrigation (SDI) systems that deliver on-farm water savings can alter soil physico-chemical properties and reduce yields of processing tomatoes (Lycopersicon esculentum Mill). We hypothesized that soil microbial communities will also be modified with proximity to SDI emitters. Bacterial and fungal alpha and beta diversity were analysed using soil samples near to (within 15 cm) and distant from (45 cm laterally) SDI emitters in two adjacent fields used for commercial processing tomato production. One field had an established SDI system and four seasons of cropping under irrigation while the second field had a recently installed SDI system and one season of cropping. Bacterial diversity was significantly reduced near the emitter only in the recent SDI field. Bacterial community structure was also determined by proximity to the emitter in both fields. Several bacterial genera contributed to the dissimilarity of communities near and distant from the emitter including Acidobacteria subgroups 3 and 6, Gaiella, Gemmatimonas and Flavobacterium. Fungal alpha diversity was not significantly affected by emitter proximity in the two fields though it was lower overall in the established SDI field. Fungal community structure was also significantly different based on emitter proximity in both fields. Several fungal genera that contributed to the dissimilarity of communities near and distant from the emitter including Glomus, Preussia, Embellisia, Podospora, Gibberella and Plectosphaerella. Redundancy analysis identified pH, available phosphorus (Colwell P), potassium and magnesium as predictors of bacterial and fungal community structure in the two fields. This study has identified that SDI emitter proximity modifies the abundance of specific bacterial and fungal genera implicated in plant and soil health, thereby providing new information to improve the management of SDI systems for sustained yields of processing tomatoes.
查看更多>>摘要：? 2021Long-term cultivation of woody species would change soil microbial community and metabolites composition, and then affect soil ecological function. Camellia oleifera is an important economically cultivar grown in subtropical regions of China but its effect on soil quality and health remains unclear. Soil bacterial communities and metabolome composition are investigated in this study via high-throughput sequencing and soil metabolomics to determine soil quality under different growth stages (sapling, maturity, and degeneration periods) of C. oleifera. Main results revealed that soil metabolite composition reaches equilibrium faster than microorganisms. Higher carbohydrate content (such as trehalose, mannopyranose, and sucrose) during degeneration stages of C. oleifera induces the decrease of Chloroflexi and Actinobacteria abundances and results in lower disease resistance potential than that of sapling and mature stages. Long-term cultivation of C. oleifera soil showed significantly higher abundance of carbon, nitrogen, and phosphorus metabolism, and presented significantly higher soil organic matter, available nitrogen, and available phosphorus contents. Results demonstrated that long-term C. oleifera cultivation can significantly improve soil fertility but potentially cause the decline of soil ecological health.
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Elsevier