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Anthropogenic nitrogen (N) input is known to alter the soil microbiome, but how N enrichment influences the abundance, alpha-diversity and community structure of N-cycling functional microbial communities in grasslands remains poorly understood. Here, we collected soils from plant communities subjected to up to 9 years of annual N-addition (10 g N m−2 per year using urea as a N-source) and from unfertilized plots (control) in 30 grasslands worldwide spanning a large range of climatic and soil conditions. We focused on three key microbial groups responsible for two essential processes of the global N cycle: N2 fixation (soil diazotrophs) and nitrification (AOA: ammonia-oxidizing archaea and AOB: ammonia-oxidizing bacteria). We targeted soil diazotrophs, AOA and AOB using Illumina MiSeq sequencing and measured the abundance (gene copy numbers) using quantitative PCR. N-addition shifted the structure of the diazotrophic communities, although their alpha-diversity and abundance were not affected. AOA and AOB responded differently to N-addition. The abundance and alpha-diversity of AOB increased, and their community structure shifted with N-addition. In contrast, AOA were not affected by N-addition. AOA abundance outnumbered AOB in control plots under conditions of low N availability, whereas N-addition favoured copiotrophic AOB. Overall, N-addition showed a low impact on soil diazotrophs and AOA while effects for AOB communities were considerable. These results reveal that long-term N-addition has important ecological implications for key microbial groups involved in two critical soil N-cycling processes. Increased AOB abundance and community shifts following N-addition may change soil N-cycling, as larger population sizes may promote higher rates of ammonia oxidation and subsequently increase N loss via gaseous and soil N-leaching. These findings bring us a step closer to predicting the responses and feedbacks of microbial-mediated N-cycling pr

Background Bio-based and biodegradable plastics are considered as plastics of the future owing to their ability to decompose under various environmental conditions. However, their effects on the soil microbiome are poorly characterised. In this study, we aimed to investigate the effects of an important bio-based and biodegradable plastic, polybutylene succinate-co-adipate (PBSA), on soil microbial diversity and community composition using high-resolution molecular technique (Illumina sequencing) targeting all three microbial domains: archaea, bacteria, and fungi. Results Adding high load of PBSA to soil (6% (w/w)) caused a significant decline in archaeal (13%) and fungal (45%) richness and substantial changes in both bacterial (Proteobacteria, Actinobacteria, and Acidobacteria) and fungal (Eurotiomycetes, Sordariomycetes, Leotiomycetes, and Dothideomycetes) community composition compared with no PBSA addition to soil. The combined effects of PBSA and (NH4)2SO4 fertilisation on the soil microbiome were much greater than the effects of PBSA alone. We only detected opportunistic human pathogens in low abundance on PBSA and in the surrounding soil. However, some plant pathogenic fungi were detected and/or enriched on the PBSA films and in surrounding soil. Apart from plant pathogens, many potential microbial control agents and plant growth-promoting microorganisms were also detected/enriched owing to PBSA addition. Adding high load of PBSA together with (NH4)2SO4 fertilisation can either eliminate some plant pathogens or enrich specific pathogens, especially Fusarium solani, which is economically important. Conclusions We conclude that high load of bio-based and biodegradable PBSA plastic may negatively affect soil microbiome.   &nbsp

The aim of this study was to determine the effects of the inoculation of maize seeds with mixtures of bacteria (Azotobacter chroococum, Azotobacter vinelandi, Bacillus megaterium, Bacillus licheniformis) during different phenophases (6-7 leaves, silking and wax ripeness stage) and on the nitrogen dynamics, total number of microorganisms, number of azotobacter and aminoheterotrophs in Chernozem and grain yield of maize hybrid ZP 684 during 2006, 2007 and 2008. Nitrogen amount in soil was significantly higher in 2006, due to favourable meteorological conditions for microbial activity (higher total number of microorganisms and number of azotobacter), than in 2007 and 2008. The minimum amount of nitrogen was in the stage of wax ripeness although the total number of microorganisms, azotobacter and aminoheterotrophs were the largest. Seed inoculation of maize significantly increases the values of all studied parameters.

The aim of this study was to determine the effects of the inoculation of maize seeds with mixtures of bacteria (Azotobacter chroococum, Azotobacter vinelandi, Bacillus megaterium, Bacillus licheniformis) during different phenophases (6-7 leaves, silking and wax ripeness stage) and on the nitrogen dynamics, total number of microorganisms, number of azotobacter and aminoheterotrophs in Chernozem and grain yield of maize hybrid ZP 684 during 2006, 2007 and 2008. Nitrogen amount in soil was significantly higher in 2006, due to favourable meteorological conditions for microbial activity (higher total number of microorganisms and number of azotobacter), than in 2007 and 2008. The minimum amount of nitrogen was in the stage of wax ripeness although the total number of microorganisms, azotobacter and aminoheterotrophs were the largest. Seed inoculation of maize significantly increases the values of all studied parameters.

The aim of this study was to determine the effects of the inoculation of maize seeds with mixtures of bacteria (Azotobacter chroococum, Azotobacter vinelandi, Bacillus megaterium, Bacillus licheniformis) during different phenophases (6-7 leaves, silking and wax ripeness stage) and on the nitrogen dynamics, total number of microorganisms, number of azotobacter and aminoheterotrophs in Chernozem and grain yield of maize hybrid ZP 684 during 2006, 2007 and 2008. Nitrogen amount in soil was significantly higher in 2006, due to favourable meteorological conditions for microbial activity (higher total number of microorganisms and number of azotobacter), than in 2007 and 2008. The minimum amount of nitrogen was in the stage of wax ripeness although the total number of microorganisms, azotobacter and aminoheterotrophs were the largest. Seed inoculation of maize significantly increases the values of all studied parameters.

The aim of this study was to determine the effects of the inoculation of maize seeds with mixtures of bacteria (Azotobacter chroococum, Azotobacter vinelandi, Bacillus megaterium, Bacillus licheniformis) during different phenophases (6-7 leaves, silking and wax ripeness stage) and on the nitrogen dynamics, total number of microorganisms, number of azotobacter and aminoheterotrophs in Chernozem and grain yield of maize hybrid ZP 684 during 2006, 2007 and 2008. Nitrogen amount in soil was significantly higher in 2006, due to favourable meteorological conditions for microbial activity (higher total number of microorganisms and number of azotobacter), than in 2007 and 2008. The minimum amount of nitrogen was in the stage of wax ripeness although the total number of microorganisms, azotobacter and aminoheterotrophs were the largest. Seed inoculation of maize significantly increases the values of all studied parameters.

The aim of this study was to determine the effects of the inoculation of maize seeds with mixtures of bacteria (Azotobacter chroococum, Azotobacter vinelandi, Bacillus megaterium, Bacillus licheniformis) during different phenophases (6-7 leaves, silking and wax ripeness stage) and on the nitrogen dynamics, total number of microorganisms, number of azotobacter and aminoheterotrophs in Chernozem and grain yield of maize hybrid ZP 684 during 2006, 2007 and 2008. Nitrogen amount in soil was significantly higher in 2006, due to favourable meteorological conditions for microbial activity (higher total number of microorganisms and number of azotobacter), than in 2007 and 2008. The minimum amount of nitrogen was in the stage of wax ripeness although the total number of microorganisms, azotobacter and aminoheterotrophs were the largest. Seed inoculation of maize significantly increases the values of all studied parameters.