查看更多>>摘要：Tibetan Plateau grasslands embody an important ecosystem featuring vibrant biogeochemical cycles. Soil fauna, particularly nematodes, play an important role in maintaining the integrity, function, and homeostasis of such ecosystem. In the Tibetan Plateau, studies exploring the influence of frequent fertilization practices on nematode communities and subsequent repercussions impacting the entire ecosystem are scarce. To investigate the effect of long-term fertilization on nematode communities in the eastern Tibetan Plateau of China, we monitored such communities under fertilization treatments ranging from 0 to 120 g m(-2) year(-1). To gain broader insights into the dynamic interrelationships within the ecosystem, we also monitored plant communities and modeled their bidirectional relationships with soil nematodes. Our data show that with higher fertilization intensities, overall plant productivity increases. Such gains are accompanied by reduction in plant community richness and predominance of grasses on the expense of sedges, legumes, and forbs. Fertilization also impacted the abundance and species richness of nematode communities; this effect was manifest in a hump-shaped relationship with both abundance and species richness of nematode communities peaking at 60 g m(-2) year(-1). The relationship between nematode biodiversity and aboveground plant production also exhibited a predominantly hump-shaped trajectory. Our model suggests that soil acidity and the ratio of available nitrogen-to-available phosphorus had indirect, yet strong, effects on the nematode community abundance and species richness, indicating that the decline of nematode communities beyond a 60 g m(-2) year(-1) treatment could, at least in part, be attributed to unfavorable soil conditions. Our findings augment our understanding of the responses of soil fauna to nitrogen and phosphorus additions in alpine grasslands and provide scientific basis for future management of grassland fertilization.
查看更多>>摘要：Plant-related microbial communities are essential to plant growth and development, and empirical evidence suggests that inoculation with a synthetic microbial consortium can enhance plant performance; however, to manipulate the functions of these communities, we require a better understanding of the influencing factors. Here, we used the biodiversity ecosystem function (BEF) framework to specifically test the impact of community richness (1, 2, 4, or 8 strains per community) and antagonistic intensity on plant growth promotion in two kinds of nutritional environments. We found that increasing the richness of microbes can improve the accumulation of plant biomass, revealing that diversity effects were stronger than single-strain effects. The intensity of antagonism between highly diverse microbes may have a consistent negative effect on plant growth in comparison with the effects of communities with the same richness; intriguingly, this negative effect did not change positive BEF relationships. These results suggested that high diversity in the synthetic microbial consortia harboured stable and effective plant growth promotion capability and, in turn, also increased susceptibility to the negative effects of antagonism among microbial strains.
查看更多>>摘要：The widespread existence of lead (Pb) contamination in soil has received extensive attention. To effectively slow lead-ion (Pb2+) migration and promote plant growth in heavy metal-contaminated soil as well as to realize the resource utilization of solid waste, vermireactors were used to obtain vermicompost using cow dung mixed with modified mineral (MM) as feedstock material for Eisenia fetida. Vermicompost was characterized first, and then its slowing effect on Pb2+ migration in soil was further evaluated through pot experiments. The results demonstrated that earthworms could grow well in cow dung and mineral vermireactors, and earthworm activity increased the cation exchange capacity (CEC), total nutrient content and surface area but decreased the pH, carbon to nitrogen ratio (C/N) and organic matter content in the vermicompost. The addition of MM resulted in an increase in the pH, CEC, and surface area but a decrease in the C/N of the vermicompost. X-ray diffraction analysis showed that the addition of MM increased the contents of quartz, CaCO3, CaO and MgO in the vermicompost. Fourier transform infrared spectroscopy analysis indicated that comparatively less carbohydrates, lipids and polysaccharides and more aromatic compounds existed in the vermicompost, and the addition of MM increased the number of Me-O groups. Pot experiments showed that the application of vermicompost from cow dung and mineral vermireactors significantly promoted the growth of celery cabbage and reduced the Pb content in its edible parts and the Pb bioavailability in soil. Thus, it is possible to use cow dung and mineral vermireactors to optimize the properties of vermicompost for its use as a soil amendment to remediate Pb contamination.
De Marco, A.Panico, S. C.Memoli, V.Santorufo, L....
11页
查看更多>>摘要：Plant cover and microclimatic conditions can profoundly alter the balance between productivity and decay, with relevant effects on soil carbon (C) and nitrogen (N) pools. Despite their importance, the combined effects of plant cover and microclimatic conditions on soil C and N pools have been poorly assessed, especially in the Mediterranean environment. Therefore, the aims of the present study were to assess how, in Mediterranean areas, C and N pools differ between afforested pine forests and natural shrublands and to highlight the different impacts of plant cover on C and N sequestration at low and high elevations Along a forest floor-mineral soil continuum, plant cover and elevation effects were evaluated through measurements of C and N pools and water-soluble fractions, molecular characterization by 13C and 1H NMR, and microbial and fungal amounts and activities. Our data show that C accumulated more in afforested pine forest soils than in shrubland soils, especially at low elevations. In pine forests, the higher content of aromatic and O alkyl compounds in the upper organic layers and the abundance of aromatic and carboxylic components in the soluble fraction suggest a greater stability of soil organic matter than in shrublands. Additionally, the high concentration of N in the upper organic layer and its reduction in the fermentative layer stimulate soil C accumulation mainly in pine forests at low elevations. The abundant organic mass at high elevations in pine forests improves microbial growth, whereas the greater recalcitrance of organic residues at low elevations in pine forests leads to a decrease in the bacterial component compared with the fungal component. In conclusion, the plant cover effect appears to be strongly conditioned by elevation, and afforestation with pine at low elevations could favour long-term soil C storage.
查看更多>>摘要：Application of raw or char material may modify the influence of earthworm activity on soil phosphorus (P) transformation. The purpose of this study was to investigate the effect of cow manure or cow manure biochar addition and its interaction with earthworm on organic (Po) and inorganic (Pi) P fractions, alkaline phosphatase activity and P-solubilizing bacteria (PSB) in a calcareous soil of semi-arid region. For this purpose, the soil was amended with cow manure and its biochar in 4 levels (0, 1, 2 and 5%) in the absence and presence of earthworm (Eisenia fetida). The treatments were then incubated for 90 days. The monitoring of earthworms was also carried out after 30 and 90 days incubation. The results showed an increase in weight of earthworms in control and cow manure amended soils at both incubation times. However, application of cow manure biochar resulted in mortality and an initial weight loss of earthworms (36-85%) at 30 days incubation. This negative effect decreased over time, so that the earthworms recovered in 1% biochar amended soil. Amendment additions increased proportion of NaHCO3-Pi and NaOH-Pi but decreased proportion of HCl-Pi, residual-P, NaOH-Po and HCl-Po, making P more available in soil. The impact of cow manure biochar on the NaHCO3-Pi and NaOH-Pi fractions was stronger than that of cow manure. Earthworm decreased the proportion of Pi fractions but increased the proportion of Po fractions, indicating a transformation of P from Pi to Po forms. Alkaline phosphatase activity and PSB number were also increased as affected by earthworm and amendment (especially cow manure) additions. No significant interaction between earthworm and amendment additions was observed (p < 0.05), indicating that the influence of earthworm on P transformations was not dependent on amendment additions. Overall, we concluded that biochar can be useful for the amendment of semi-arid calcareous soil in terms of P availability, but the negative response of earthworms to biochar and its effect on other soil processes should be taken into consideration.
查看更多>>摘要：The use of charred organic materials (biochar) as soil amendment can alter soil nutrient, microbial abundance, and their diversities. These alterations can be influenced by the biochar source, application method and amount, but the details are still unknown. Thus, this study aimed to compare two methods of biochar application (surface or mixed) on carbon (C) and nitrogen (N) losses with their related effect on microbial community under C-depleted sandy soil. Chicken manure (CM), rice husk (RH) and rice straw (RS), pyrolyzed at 350 degrees C to produce biochar, were tested in a pot trial. The biochar was applied singly, and in combined forms (CM + RH and CM + RS) under dent corn, as mixed (incorporated) or surface application, at different rates of 0, 15, and 30 g kg(-1) soil (equivalent to 0, 7.5 and 15.0 Mg ha(-1)). The soil respiration (S-R), leaching loss of organic-C and inorganic-N (as nitrate-N), microbial biomass C at top 10 cm soils, bacterial relative abundance and community structure were measured. The application methods' effect on S-R was unclear but the surface application reduced the C leaching loss and increased nitrate-N loss compared to the mixed application, in general. The microbial biomass C was found to be significantly higher (P < 0.001) under the surface applied (459 +/- 252 mg C kg(-1) soil) compared to the mixed applied (76.1 +/- 18.5 mg C kg(-1) soil). Surface application of biochar also increased microbial diversity on soil surface. The increase in diversity was characterized by an increase in OTU numbers within the phylum Actinobacteria and Proteobacteria. We concluded that surface application of biochar increased the microbial di-versities in the soil and thus, can retain C in low C soils through higher immobilization of C, but might be un-suitable when biochar is applied with the aim being to reduce nitrate-N loss in soils.
查看更多>>摘要：While the endosphere is a hotspot for close interactions between plants and microbes, the influence of different components of the root endosphere on microbiome composition are seldom explored. This study used the fleshy taprooted plant, American Ginseng (Panax quinquefolius) and the recently discovered beneficial microbe, Trichoderma atroviride strain HB20111, to provide insights into microbiome shifts across plant-soil compartment niches including the bulk soil, rhizosphere, epidermis, cortex and vascular tissue. Trichoderma impacted both plant growth and microbiome composition. The survival rate of ginseng plants significantly increased from 70.8% to 85.4%, following Trichoderma treatment while root biomass production increased by 1.2 to 1.5 times compared with the uninoculated control. Microbiome diversity gradually decreased in niches from the bulk soil outside the root toward the vascular tissue, indicating increased selection and suggesting the possibility of a Trichoderma-driven induced systemic or localized resistance. The significant reduction (P < 0.05) in relative abundance of ginseng bacterial pathogens at the cortex confirmed the biocontrol capability of strain HB20111. We conclude that application of Trichoderma can improve growth of American Ginseng and mediate endosphere microbiome composition, resulting in plant pathogen inhibition.
Carlos, Filipe SelauSchaffer, NaihanaMariot, Roberta FogliattoFernandes, Rodrigo Schmitt...
11页
查看更多>>摘要：Due to the genetic improvement of soybean cultivars more adapted to lowlands and to new drainage technologies, there has been a great insertion of soybean cultivation in rotation with irrigated rice in South America. Soybean has innumerable features beyond the fact that it is a legume, which can directly impact the microbial activity and diversity of the soil and the development of crops established in succession. Therefore, the objective was to evaluate nitrogen (N) dynamics, extracellular enzyme activity, soil microbial community, and the subsequent development of ryegrass in a Gleysol cultivated with irrigated rice and soybean in an area with a long history of irrigated rice cultivation. The experiment was conducted in the crop season 2015/16 at the Rice Research Station, Rio Grande do Sul, Southern Brazil, in an area that had been cultivated for 70 years with irrigated rice. The treatments used are irrigated rice cultivation and soybean in randomized blocks with 4 replicates. Hydrolysis of fluorescein diacetate, acid phosphatase, urease and beta-glucosidase were evaluated. Bacterial communities were estimated in soil by extracting DNA and sequencing the V3-V4 region of the 16S rRNA gene. Ryegrass dry biomass was quantified after irrigated rice and soybean. Greater mineral N availability (+ 49%), higher extracellular enzyme activity (+ 51%) and microbial diversity (+ 7%) were observed after soybean cultivation compared to irrigated rice. These changes, after soybean cultivation, had a direct impact on the development of ryegrass plants, which showed higher ryegrass dry biomass production. Thus, the adoption of soybean rotation in areas traditionally cultivated with irrigated rice is an important agronomic strategy to increase the sustainability of agriculture, since it allows the increase of soil quality and availability of nutrients in lowland crop production systems.
查看更多>>摘要：Soil enzyme activities can indicate soil quality due to the catalyst roles enzymes play in various soil biochemical processes. However, little is known about the variations in soil enzyme activities among different plant communities with diverse environmental conditions. Here, the activities of four soil enzymes, catalase (CA), urease (UA), polyphenol oxidase (POA) and saccharase (SA), were investigated in shrub lands, forest lands and abandoned cropland on the Loess Plateau, China. Soil microbial biomass (MB) that contained bacteria, fungi and actinomycetes was also analyzed to determine the variations in enzyme activities. The results showed that soil enzyme activities varied significantly among different plant communities. Land uses, climate factors, topography and soil properties are all related to variations in enzyme activities. Specifically, soil properties including soil nutrients and MB were stable driving factors. With increasing soil MB, UA increased linearly, but CA, POA and SA increased exponentially, which might have resulted from soil nutrient deficiencies. Different plant communities with diverse microbial metabolisms performed differently in terms of soil enzyme activities, for example, in comparison to the other studied species, Hippophae rhamnoides had the greatest advantages and could improve the soil environment more effectively. Therefore, we suggest that the afforestation of Hippophae rhamnoides is an appropriate scenario for vegetation restoration in the typical hilly region of the Loess Plateau. Abbreviations:
查看更多>>摘要：Soil microbial community structure is determined by environmental conditions and influenced by other factors, such as the intensity of the land use management. Studies addressing the effect of environmental factors and management on grassland soil microbial communities at the continental scale are missing, and the wide range of ecosystem services provided by these ecosystems are thus also wanting. To address this knowledge gap, this study presents data on grassland soil microbial communities along a pan-European agro-ecological gradient. The transect included five geographical locations (Sweden, Germany, Switzerland, Portugal mainland, Portugal Azores). At each location, soils were collected in two regions characterized by favourable and less favourable conditions for plant growth. In each of these ten regions, grasslands along a gradient of management intensity were selected, i.e. grassland under intensive, less intensive and extensive management. Phospholipid fatty acid analysis (PLFA) was used to characterize the microbial community structure (PLFA pattern) in relation to climatic and soil properties. Over the whole geographical range, the environmental properties determined the soil microbial community structure. In Sweden and Switzerland, the regional growth conditions had the strongest influence on the soil microbial communities, while in Germany, Portugal mainland and Azores the management intensity was more important. Splitting up this whole community response into individual groups reveals that, in general, saprotrophic fungal biomarkers were highest in extensively managed grasslands while bacterial biomarkers differed mainly between the regions. We conclude that at the transect level, climate and soil properties were the most important factors influencing soil bacterial community structure, while soil fungal groups were more responsive to grassland management intensity. Overall agricultural sustainability could benefit from informed soil health promoting management practices, and this study contributes to such knowledge, showing the importance of management for the soil microbial biomass and community structure.
NSTL
Elsevier