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Nitrogen (N) fertilization has boosted grain production during the past century, while excess N fertilization with declining N use efficiency (NUE) has led to severe pollution in many regions. To achieve the goal of sustainable food production, Technologies and Management Practices (TMPs, e.g., optimum N application rate and methods, N‐transformation inhibitors) have been developed to improve crop yield and NUE and to reduce N losses. However, it remains unclear how N fate has been changed by environmental factors and TMPs. Here, we compiled a dataset of 366 field 15N tracer observations from 74 publications worldwide and conducted a meta‐analysis to examine how environmental conditions and management practices influence the fertilizer‐N fate one growing season after the fertilization of maize. We show that the proportion of 15N taken up by aboveground biomass (NUE15N), was significantly lower in China (33%) than that in North America (42%) and the European Union (54%). Soil organic carbon was the most critical environmental factor positively correlated with NUE15N. Among the nine selected categories of TMPs, deep placement of fertilizer and split application increased the grain yield and decreased the fertilizer‐N loss consistently among studies. Reducing the fertilizer‐N rate could increase the NUE15N but presents risks of yield reduction in some regions. This study demonstrates the importance of SOC and varying impacts of TMPs on the efficiency of fertilizer use in cropping systems globally and provides critical information for farmers and policymakers to improve N management for higher productivity and less pollution. Plain Language Summary: The efficient use of Nitrogen (N) fertilizer benefits both food security and environmental quality. To characterize the fate and the efficiency of fertilizer‐N in maize production, we conducted a comprehensive meta‐analysis with existing field 15N‐tracer trials. Our results show that higher organic carbon content in the soil is associated with higher 15N recovery under conventional management practices. Among nine N management practices developed for more efficient use of N, deep placement in the soil (rather than surface application) and split application of N fertilizer (dividing annual fertilization into two or more smaller applications) improved yield, 15N recovery, and environmental impacts. This study improves our understanding of management practices on the fate of fertilizer‐N and provides guidance for farmers and policymakers to improve N fertilizer management. Key Points: Globally, 41 ± 14%, 31 ± 14%, and 28 ± 19% of N fertilizer was taken up by maize, retained in the soil and lost one season after its applicationThe nitrogen use efficiency measured with 15N approach is low in Chinese maize cropping system mainly due to low soil organic carbonDeep placement of N fertilizer and split fertilization can improve yield and reduce N loss [ABSTRACT FROM AUTHOR]

Summary: Plants harbour highly diverse mycobiomes which sustain essential functions for host health and productivity. However, ecological processes that govern the plant–mycobiome assembly, interactions and their impact on ecosystem functions remain poorly known. Here we characterized the ecological role and community assembly of both abundant and rare fungal taxa along the soil–plant continuums (rhizosphere, phyllosphere and endosphere) in the maize–wheat/barley rotation system under different fertilization practices at two contrasting sites. Our results indicate that mycobiome assembly is shaped predominantly by compartment niche and host species rather than by environmental factors. Moreover, crop‐associated fungal communities are dominated by few abundant taxa mainly belonging to Sordariomycetes and Dothideomycetes, while the majority of diversity within mycobiomes are represented by rare taxa. For plant compartments, the abundant sub‐community is mainly determined by stochastic processes. In contrast, the rare sub‐community is more sensitive to host selection and mainly governed by deterministic processes. Furthermore, our results demonstrate that rare taxa play an important role in fungal co‐occurrence network and ecosystem functioning like crop yield and soil enzyme activities. These results significantly advance our understanding of crop mycobiome assembly and highlight the key role of rare taxa in sustaining the stability of crop mycobiomes and ecosystem functions. [ABSTRACT FROM AUTHOR]

Summary: Viruses can affect microbial dynamics, metabolism and biogeochemical cycles in aquatic ecosystems. However, viral diversity and functions in agricultural soils are poorly known, especially in the rhizosphere. We used virome analysis of eight rhizosphere and bulk soils to study viral diversity and potential biogeochemical impacts in an agro‐ecosystem. The order Caudovirales was the predominant viral type in agricultural soils, with Siphoviridae being the most abundant family. Phylogenetic analysis of the terminase large subunit of Caudovirales identified high viral diversity and three novel groups. Viral community composition differed significantly between bulk and rhizosphere soils. Soil pH was the main environmental driver of the viral community structure. Remarkably, abundant auxiliary carbohydrate‐active enzyme (CAZyme) genes were detected in viromes, including glycoside hydrolases, carbohydrate esterases and carbohydrate‐binding modules. These results demonstrate that virus‐encoded putative auxiliary metabolic genes or metabolic genes that may change bacterial metabolism and indirectly contribute to biogeochemical cycling, especially carbon cycling, in agricultural soil. [ABSTRACT FROM AUTHOR]

Summary: Plant microbiomes are essential to host health and productivity but the ecological processes that govern crop microbiome assembly are not fully known.Here we examined bacterial communities across 684 samples from soils (rhizosphere and bulk soil) and multiple compartment niches (rhizoplane, root endosphere, phylloplane, and leaf endosphere) in maize (Zea mays)‐wheat (Triticum aestivum)/barley (Hordeum vulgare) rotation system under different fertilization practices at two contrasting sites.Our results demonstrate that microbiome assembly along the soil‐plant continuum is shaped predominantly by compartment niche and host species rather than by site or fertilization practice. From soils to epiphytes to endophytes, host selection pressure sequentially increased and bacterial diversity and network complexity consequently reduced, with the strongest host effect in leaf endosphere. Source tracking indicates that crop microbiome is mainly derived from soils and gradually enriched and filtered at different plant compartment niches. Moreover, crop microbiomes were dominated by a few dominant taxa (c. 0.5% of bacterial phylotypes), with bacilli identified as the important biomarker taxa for wheat and barley and Methylobacteriaceae for maize.Our work provides comprehensive empirical evidence on host selection, potential sources and enrichment processes for crop microbiome assembly, and has important implications for future crop management and manipulation of crop microbiome for sustainable agriculture. [ABSTRACT FROM AUTHOR]