Agricultural food production is at the base of food and fodder, with fertilization having fundamentally and continuously increased crop yield over the last decades. The performance of crops is ...intimately tied to their microbiome as they together form holobionts. The importance of the microbiome for plant performance is, however, notoriously ignored in agricultural systems as fertilization disconnects the dependency of plants for often plant-beneficial microbial processes. Moreover, we lack a holistic understanding of how fertilization regimes affect the soil microbiome. Here, we examined the effect of a 2-year fertilization regime (no nitrogen fertilization control, nitrogen fertilization, and nitrogen fertilization plus straw amendment) on entire soil microbiomes (bacteria, fungi, and protist) in three common agricultural soil types cropped with maize in two seasons.
We found that the application of nitrogen fertilizers more strongly affected protist than bacterial and fungal communities. Nitrogen fertilization indirectly reduced protist diversity through changing abiotic properties and bacterial and fungal communities which differed between soil types and sampling seasons. Nitrogen fertilizer plus straw amendment had greater effects on soil physicochemical properties and microbiome diversity than nitrogen addition alone. Moreover, nitrogen fertilization, even more together with straw, increased soil microbiome network complexity, suggesting that the application of nitrogen fertilizers tightened soil microbiomes interactions.
Together, our results suggest that protists are the most susceptible microbiome component to the application of nitrogen fertilizers. As protist communities also exhibit the strongest seasonal dynamics, they serve as the most sensitive bioindicators of soil changes. Changes in protist communities might have long-term effects if some of the key protist hubs that govern microbiome complexities as top microbiome predators are altered. This study serves as the stepping stone to promote protists as promising agents in targeted microbiome engineering to help in reducing the dependency on exogenous unsustainably high fertilization and pesticide applications.
Controlled experiments have shown that global changes decouple the biogeochemical cycles of carbon (C), nitrogen (N), and phosphorus (P), resulting in shifting stoichiometry that lies at the core of ...ecosystem functioning. However, the response of soil stoichiometry to global changes in natural ecosystems with different soil depths, vegetation types, and climate gradients remains poorly understood. Based on 2,736 observations along soil profiles of 0–150 cm depth from 1955 to 2016, we evaluated the temporal changes in soil C‐N‐P stoichiometry across subtropical China, where soils are P‐impoverished, with diverse vegetation, soil, and parent material types and a wide range of climate gradients. We found a significant overall increase in soil total C concentration and a decrease in soil total P concentration, resulting in increasing soil C:P and N:P ratios during the past 60 years across all soil depths. Although average soil N concentration did not change, soil C:N increased in topsoil while decreasing in deeper soil. The temporal trends in soil C‐N‐P stoichiometry differed among vegetation, soil, parent material types, and spatial climate variations, with significantly increased C:P and N:P ratios for evergreen broadleaf forest and highly weathered Ultisols, and more pronounced temporal changes in soil C:N, N:P, and C:P ratios at low elevations. Our sensitivity analysis suggests that the temporal changes in soil stoichiometry resulted from elevated N deposition, rising atmospheric CO2 concentration and regional warming. Our findings revealed that the responses of soil C‐N‐P and stoichiometry to long‐term global changes have occurred across the whole soil depth in subtropical China and the magnitudes of the changes in soil stoichiometry are dependent on vegetation types, soil types, and spatial climate variations.
During the study period, atmospheric CO2 concentration and annual temperature anomalies significantly increased, while precipitation anomalies slightly decreased across subtropical China. The responses of soil C‐N‐P and stoichiometry to rising atmospheric CO2 concentration and temperature anomalies were similar, with significantly decreased soil total P concentrations and increased ratios of C:N, C:P, and N:P.
•Higher values of the site parameters leads to higher responses.•The effect of pounding could be either destructive or beneficial.•The soil type has a significant effect on the response of the ...colliding buildings.
The effect of the soil type on buildings experiencing pounding during earthquakes is investigated in this study using the incremental dynamic analysis and fragility assessment methods. Three 3-D structures with different number of storeys (4, 6 and 8) were considered in this study. Three pounding scenarios between these three buildings were taken into account, i.e. pounding between 4-storey and 6-storey buildings, between 4-storey and 8-storey buildings and between 6-storey and 8-storey buildings. First, the effect of the site parameters was investigated so as to take into consideration the values that lead to higher responses. Then, the effects of earthquake-induced pounding between buildings founded on a specified soil type for these three pounding scenarios were analysed and compared with no pounding case. Finally, pounding for these three scenarios was studied under different soil types defined in the ASCE 7–10 code (hard rock, rock, very dense soil and soft rock, stiff soil and soft clay soil). The results of this study indicate that the effect of pounding follows two general trends which are destructive and beneficial. Also, the vibrating buildings were found to be more vulnerable to damage due to pounding when they are founded on the soft clay soil, then when they are founded on the stiff soil, then when they are founded on very dense soil and soft rock, and finally when they are founded on the rock and hard rock.
Earthquake-induced pounding was experienced in many previous earthquakes and it was found to be a critical issue. This study investigates the effect of pounding between buildings founded on the same ...and different soil types. Three 3-D buildings with 4, 6 and 8 storeys were considered in this study. Three pounding scenarios were taken into account, i.e. pounding between 4-storey and 6-storey buildings, between 4-storey and 8-storey buildings and between 6-storey and 8-storey buildings. To consider the soil type, the effects of different site parameters on the response of buildings exposed to earthquakes was firstly investigated so that the values that lead to significant effects and larger responses could be taken into account in further study related to structural interactions. In the next stage of the investigation, the effects of pounding between buildings founded on a specified soil type were analysed and compared with the no pounding case. The results of this part of this study show that pounding significantly increases the peak accelerations in all situations. Indeed, the peak displacements experience both amplification and de-amplification. Moreover, the shear forces were found to be increased for all storeys in all the cases with few exceptions concerning the top storeys. Finally, pounding between 4-storey and 8-storey buildings as well as between 6-storey and 8-storey buildings was considered under different soil types defined in the ASCE 7–10 code (hard rock, rock, very dense soil and soft rock, stiff soil and soft clay soil). The results of this stage of this study show that the highest displacements and shear forces can be expected for buildings founded on the soft clay soil, then for buildings founded on the stiff soil, then for buildings founded on very dense soil and soft rock, and finally for buildings founded on the rock and hard rock.
•Pounding significantly increases accelerations of colliding buildings during the whole duration of the ground motion.•The displacements of colliding buildings experience both amplification and de-amplification.•Pounding significantly increases the storeys shears of the colliding buildings with few exceptions at the top storeys.•Pounding leads to the generation of large impact forces which are not considered in the engineering design.•The soil type has a significant effect on the response of colliding buildings.
Arbuscular fungi have a major role in directing the functioning of terrestrial ecosystems yet little is known about their biogeographical distribution. The Baas-Becking hypothesis ('everything is ...everywhere, but, the environment selects') was tested by investigating the distribution of arbuscular mycorrhizal fungi (AMF) at the landscape scale and the influence of environmental factors and geographical distance in determining community composition. AMF communities in Trifolium repens and Lolium perenne roots were assessed in 40 geographically dispersed sites in Ireland representing different land uses and soil types. Field sampling and laboratory bioassays were used, with AMF communities characterised using 18S rRNA terminal-restriction fragment length polymorphism. Landscape-scale distribution of AMF was driven by the local environment. AMF community composition was influenced by abiotic variables (pH, rainfall and soil type), but not land use or geographical distance. Trifolium repens and L. perenne supported contrasting communities of AMF, and the communities colonising each plant species were consistent across pasture habitats and over distance. Furthermore, L. perenne AMF communities grouped by soil type within pasture habitats. This is the largest and most comprehensive study that has investigated the landscape-scale distribution of AMF. Our findings support the Baas-Becking hypothesis at the landscape scale and demonstrate the strong influence the local environment has on determining AMF community composition.
Microplastic (MP) pollution in terrestrial ecosystems has aroused great concern. However, little is known regarding the distribution of MPs in Sand Land soils and their associated destinies. We ...investigated the MPs pollution in different areas, different vegetation cover and restoration years in Mu Us Sand Land soils. The results clearly showed that the soils of Mu Us Sand Land contain a relatively higher MPs abundance. The significant differences of MPs abundance were demonstrated among soil from sand, grassland and woodland, which the total MP abundance of sand soil was higher than that of grassland and woodland. The distribution of MP size in the woodland area primarily from 0 to 0.50 mm, which is significantly higher than that other areas. In addition, the highest concentration of MP collected was found at Salix tree (ST), followed by Poplar tree (PT) and Chinese pine (CP), while the lowest concentration was at Pinus sylvestris (PSs) and Jujube tree (JT). It is worth noting that the abundance of MPs decreases with restoration years increased, whether it is PT or PSs. We speculate that the tree disturbance in the sampling area might affect the distribution of microplastics and then be conducive to plastic fragmentation.
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•The abundance of microplastics exhibited exceptionally high level of MPs.
•The microplastic abundance of sand was higher than that of grassland and woodland.
•Microplastics size decreased gradually with the enhancement of repair degree.
•Different types of cover vegetation may influence the distribution of microplastic.
•Microplastics disturbance may be related to the history of restoration years.
Biological nitrogen fixation plays an important role in nitrogen cycling by transferring atmospheric N2 to plant-available N in the soil. However, the diazotrophic activity and distribution in ...different types of soils remain to be further explored. In this study, 152 upland soils were sampled to examine the diazotrophic abundance, nitrogenase activity, diversity and community composition by quantitative polymerase chain reaction, acetylene reduction assay and the MiSeq sequencing of nifH genes, respectively. The results showed that diazotrophic abundance and nitrogenase activity varied among the three soil types. The diazotrophic community was mainly dominated by Bradyrhizobium, Azospirillum, Myxobacter, Desulfovibrio and Methylobacterium. The symbiotic diazotroph Bradyrhizobium was widely distributed among soils, while the distribution of free-living diazotrophs showed large variation and was greatly affected by multiple factors. Crop type and soil properties directly affected the diazotrophic ɑ-diversity, while soil properties, climatic factors and spatial distance together influenced the diazotrophic community. Network structures were completely different among all three types of soils, with most complex interactions observed in the Red soil. These findings suggest that diazotrophs have various activities and distributions in the three soil types, which played different roles in nitrogen input in agricultural soil in China, being driven by multiple environmental factors.
Impact of soil type, soil-metal(loids) and soil-pH of rice paddies on grain-arsenic (As) and cadmium (Cd) accumulation in Malawian rice was investigated to explore the extent to which Malawi's ...geographical location, soil types, soil-metal(loids) and soil-pH and their interactions impact on grain-As and Cd accumulation. Multivariate techniques were used to evaluate the relationships among measured parameters. Results showed that the 1st three principal components consisting of soil-types, soil-metal(loids) and soil-pH explained 83% of total variance of both grain-As and Cd accumulation. For As, highest grain-As was detected in rice from central region (CR) cultivated in vertisols characterized with soil-As ≥ 2.5 mg/kg and soil-pH > 7.0 whereas the lowest was in rice from northern region (NR) cultivated in fluvisols characterized with soil-As ≤ 1.5 mg As/kg soil and soil-pH range of 6.00–6.99. For Cd, highest grain-Cd was detected in rice from CR cultivated in luvisols with soil-As range of 2.0–3.0 mg/kg and soil-pH < 6.0. For correlation, highest significant correlation coefficient was between soil-As and grain-As (0.512; p < 0.001); and soil-pH and soil-As (0.545; p < 0.001) while correlation coefficient between soil-Cd and grain-Cd and soil-Cd and grain-As were weaker and/or non-significant. These results indicate a synergy impact of soil type, soil-pH, and soil-metal(loids) that simultaneously influence low grain-As and Cd accumulation.
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Sewage sludge was generally considered a significant reservoir of antibiotic resistance genes (ARGs) and could enter agricultural systems as fertilizer after composting. Soil types and the ...discrepancy of sludge composts could have influenced the fate of antibiotic-resistant bacteria (ARB) following the land application of sludge composts, which deserved to be clarified. Thus, the fate of ARB and ARGs following the land application of three types of sludge composts (A, B, and C) to three different soils (red soil, loess, and black soil) was investigated. The results showed that tetX, which was enriched the most during composting, did not affect the soil resistome, whereas tetG did. Soil types influenced the dynamics of ARB and ARGs significantly, whereas no significant difference was observed among compost types. The advantage of reducing ARGs during the composting process in compost B did not extend to land application. Land application of composts influenced the microbial community significantly at the early stage, but the microbial community returned to the control pattern gradually. Changes in the microbial community contributed more to the dynamics of ARGs in red and black soil compared with other factors, including co-selection from heavy metals, horizontal gene transfer, biomass and environmental factors, whereas horizontal gene transfer, reflected by intI1 levels, contributed the most in loess.
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•Soil types contribute more to the fate of antibiotic resistance than composts.•Sludge composts led to ARB enrichment especially resistance to cefotaxime in soils.•The tetG could be the biomarker for evaluating land application of sludge compost.•The advantage of ARGs reduction in sludge composting did not extend to the soils.•The main contributor to the evolution of ARGs varied from soil types.
Adoption of no-till management on croplands has become a controversial approach for storing carbon in soil due to conflicting findings. Yet, no-till is still promoted as a management practice to ...stabilize the global climate system from additional change due to anthropogenic greenhouse gas emissions, including the 4 per mille initiative promoted through the UN Framework Convention on Climate Change. We evaluated the body of literature surrounding this practice, and found that SOC storage can be higher under no-till management in some soil types and climatic conditions even with redistribution of SOC, and contribute to reducing net greenhouse gas emissions. However, uncertainties tend to be large, which may make this approach less attractive as a contributor to stabilize the climate system compared to other options. Consequently, no-till may be better viewed as a method for reducing soil erosion, adapting to climate change, and ensuring food security, while any increase in SOC storage is a co-benefit for society in terms of reducing greenhouse gas emissions.
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