Land degradation causes great changes in the soil biological properties.The process of degradation may decrease soil microbial biomass and consequently decrease soil microbial activity.The study was conducted out duri...Land degradation causes great changes in the soil biological properties.The process of degradation may decrease soil microbial biomass and consequently decrease soil microbial activity.The study was conducted out during 2009 and 2010 at the four sites of land under native vegetation(NV),moderately degraded land(LDL),highly degraded land(HDL) and land under restoration for four years(RL) to evaluate changes in soil microbial biomass and activity in lands with different degradation levels in comparison with both land under native vegetation and land under restoration in Northeast Brazil.Soil samples were collected at 0-10 cm depth.Soil organic carbon(SOC),soil microbial biomass C(MBC) and N(MBN),soil respiration(SR),and hydrolysis of fluorescein diacetate(FDA) and dehydrogenase(DHA) activities were analyzed.After two years of evaluation,soil MBC,MBN,FDA and DHA had higher values in the NV,followed by the RL.The decreases of soil microbial biomass and enzyme activities in the degraded lands were approximately 8-10 times as large as those found in the NV.However,after land restoration,the MBC and MBN increased approximately 5-fold and 2-fold,respectively,compared with the HDL.The results showed that land degradation produced a strong decrease in soil microbial biomass.However,land restoration may promote short-and long-term increases in soil microbial biomass.展开更多
Based on data from 10-year field experiments on residue/fertilizer management in the dryland farming region of northern China, Century model was used to simulate the site-specific ecosystem dynamics through adjustment...Based on data from 10-year field experiments on residue/fertilizer management in the dryland farming region of northern China, Century model was used to simulate the site-specific ecosystem dynamics through adjustment of the model＇s parameters, and the applicability of the model to propose soil organic carbon （SOC） management temporally and spatially, in cases such as of tillage/residue/fertilization management options, was identified v/a scenario analysis.Results between simulations and actual measurements were in close agreement when appropriate applications of stover,manure and inorganic fertilizer were combined. Simulations of extreme C/N ratios with added organic materials tended to underestimate the measured effects. Scenarios of changed tillage methods, residue practices and fertilization options showed potential to maintain and enhance SOC in the long run, while increasing inorganic N slowed down the SOC turnover rate but did not create a net C sink without any organic C input. The Century model simulation showed a good relationship between annual C inputs to the soil and the rate of C sequestration in the top 20 cm layer and provided quantitative estimations of changes in parameters crucial for sustainable land use and management. Conservation tillage practices for sustainable land use should be integrated with residue management and appreciable organic and inorganic fertilizer application, adapted according to the local residue resource, soil fertility and production conditions. At least 50% residue return into the soil was needed annually for maintenance of SOC balance, and manure amendment was important for enhancement of SOC in small crop-livestock systems in which crop residue land application was limited.展开更多
Zero-valent iron amended biochar(ZVIB)has been proposed as a promising material in immobilizing heavy metals in paddy fields.In this study,the impacts of p H of ZVIB(p H 6.3 and p H 9.7)and watering management techniq...Zero-valent iron amended biochar(ZVIB)has been proposed as a promising material in immobilizing heavy metals in paddy fields.In this study,the impacts of p H of ZVIB(p H 6.3 and p H 9.7)and watering management techniques(watering amount in the order of CON(control,5/72)>3/72>1-3/72>3/100>1/72,with 5/72,for example,representing irrigation given to 5 cm above soil surface in 72 hr regular interval)on As and Cd bioavailability for rice and its grain yield(Yield BR)were investigated in a pot experiment.Brown rice As(As BR)content was irrelative to the watering treatments,while significantly decreased(>50%)with the addition of both ZVIB materials.The diminutions of brown rice Cd(Cd BR)content as well as the Yield BR were highly dependent on both the soil amendment materials’p H and watering amount.Among all the watering treatments,3/72 treatment(15%less irrigation water than the CON)with ZVIB 6.3 amendment was the optimum fit for simultaneous reduction of As BR(50%)and Cd BR contents(19%)as well as for significant increment(12%)of the Yield BR.Although high pH(9.7)ZVIB application could also efficiently decrease As and Cd contents in brown rice,it might risk grain yield lost if appropriate(e.g.3/72 in our study)watering management technique was not chosen.Therefore,ZVIB would be an environmentally friendly option as an amendment material with proper selection of watering management technique to utilize As and Cd co-contaminated arable soils safely for paddy cultivation.展开更多
Excessive fertilization combined with unreasonable irrigation in farmland of the Hetao Irrigation Area(HIR), China, has resulted in a large amount of nitrogen(N) losses and agricultural non-point source pollution.Appl...Excessive fertilization combined with unreasonable irrigation in farmland of the Hetao Irrigation Area(HIR), China, has resulted in a large amount of nitrogen(N) losses and agricultural non-point source pollution.Application of soil amendments has become one of the important strategies for reducing N losses of farmland.However, there is still no systematic study on the effects of various soil amendments on N losses in the HIR.In this study, three types of soil amendments(biochar, bentonite and polyacrylamide) were applied in a maize–wheat rotation system in the HIR during 2015–2017.Yields of maize and wheat, soil NH3 volatilization, N2O emission and NO3– leaching were determined and soil N balance was estimated.The results showed that applications of biochar, bentonite and polyacrylamide significantly increased yields of maize by 9.2%, 14.3% and 13.3%, respectively, and wheat by 9.2%, 16.6% and 12.3%, respectively, compared with the control(fertilization alone).Applications of biochar, bentonite and polyacrylamide significantly reduced soil N leaching by 23.1%, 35.5% and 27.1%, soil NH3-N volatilization by 34.8%, 52.7% and 37.8%, and soil N surplus by 23.9%, 37.4% and 30.6%, respectively.Applications of bentonite and polyacrylamide significantly reduced N2O-N emissions from soil by 37.3% and 35.8%, respectively, compared with the control.Compared with application of biochar, applications of bentonite and polyacrylamide increased yields of maize and wheat by 5.1% and 3.5%, respectively.Our results suggest that soil amendments(bentonite and polyacrylamide) can play important roles in reducing N losses and increasing yield for the maize–wheat rotation system in the HIR, China.展开更多
Biochar has potentials for soil fertility improvement, climate change mitigation and environmental reclamation, and charred biomass can be deliberately incorporated into soil for long-term carbon stabilization and soi...Biochar has potentials for soil fertility improvement, climate change mitigation and environmental reclamation, and charred biomass can be deliberately incorporated into soil for long-term carbon stabilization and soil amendment. Many different methods have been used for biochar production ranging from laboratory to industrial scales. However, in countryside of developing countries, biomass is generally used for cooking but not charred. Biochar production techniques at farmer scale have remained poorly developed. We developed and tested biochar production kilns for farmers with a dimension of 50.8 cm × 38.1 cm （height × diameter）, using three different setups for optimizing oxygen （02） limitation and syngas circulation： airtight with no syngas circulation （Model I）, semi-airtight with external syngas circulation （Model II） and semi-airtight with internal syngas circulation （Model III）. A comparative assessment of these biochar production kiln models was made considering biochar pyrolysis time, fuel to biomass ratio, biochar to feedstock ratio and thermogravimetric index （TGI）. Among the models, the best quality biochar （TGI ---- 0.15） was obtained from Model I kiln taking the longest time for pyrolysis （12.5 h） and the highest amount of fuel wood （1.22 kg kg-1 biomass）. Model III kiln produced comparatively good quality biochar （TGI = 0.11）, but with less fuel wood requirement （0.33 kg kg-1 biomass） and shorter pyrolysis time （8.5 h）. We also tested Model III kiln in a three times larger size under two situations （steel kiln and pit kiln）. The biochar to feedstock ratio （0.38） and quality （TGI =0.14） increased slightly for the larger kilns. Quality of biochar was found to be mainly related to pyrolysis time. The costs for the biochar stove and pit kiln were US$ 65-77, while it was US$ 154 for the large size steel kiln. Model III kiln can potentially be used for both cooking and biochar production at farmer scale.展开更多
Determining the distributions and sources of heavy metals in soils and assessing ecological risks are fundamental tasks in the control and management of pollution in mining areas.In this study,we selected 244 sampling...Determining the distributions and sources of heavy metals in soils and assessing ecological risks are fundamental tasks in the control and management of pollution in mining areas.In this study,we selected 244 sampling sites around a typical lead(Pb)and zinc(Zn)mining area in eastern Inner Mongolia Autonomous Region of China and measured the content of six heavy metals,including cuprum(Cu),Zn,Pb,arsenic(As),cadmium(Cd),and chromium(Cr).The ecological risk of heavy metals was comprehensively evaluated using the Geo-accumulation index,Nemerow general pollution index,and potential ecological risk index.The heavy metals were traced using correlation analysis and principal component analysis.The results showed that the highest content of heavy metals was found in 0–5 cm soil layer in the study area.The average content of Zn,As,Pb,Cu,Cr,and Cd was 670,424,235,162,94,and 4 mg/kg,respectively,all exceeding the risk screening value of agricultural soil in China.The areas with high content of soil heavy metals were mainly distributed near the tailings pond.The study area was affected by a combination of multiple heavy metals,with Cd and As reaching severe pollution levels.The three pathways of exposure for carcinogenic and noncarcinogenic risks were ranked as inhalation>oral ingestion>dermal absorption.The heavy metals in the study area posed certain hazards to human health.Specifically,oral ingestion of these heavy metals carried carcinogenic risks for both children and adults,as well as noncarcinogenic risks for children.There were differences in the sources of different heavy metals.The tailings pond had a large impact on the accumulation of Cd,Zn,and Pb.The source of Cr was the soil parent material,the source of As was mainly the soil matrix,and the source of Cu was mainly the nearby Cu ore.The purpose of this study is to more accurately understand the extent,scope,and source of heavy metals pollution near a typical mining area,providing effective help to solve the problem of heavy metals pollution.展开更多
Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, in...Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, information on how bacterial and fungal communities in acidic bulk and rhizosphere soils respond to swine manure and its biochar is still lacking. In this study, biochar and swine manure were applied at two rates of 1.5 and 3 t ha-1in a rice-wheat rotation field to assess how soil characteristics, especially p H and chemical element availability, correlate to compositional variations of bacteria and fungi in bulk and rhizosphere soils. Our results showed that high rates of biochar and manure promoted the bacterial richness in bulk and rhizosphere soils by increasing soil pH and reducing soil arsenic(As) and copper(Cu) availability. Compared with soil As and Cu availability, soil p H had opposite effects on beta diversity of both the bacterial and fungal communities. Specifically, biochar and swine manure applications stimulated the bacterial classes Gemmatimonadetes, Deltaproteobacteria, and Gammaproteobacteria by increasing soil pH and decreasing soil available chemical elements. Opposite trends were observed in fungal communities responding to biochar and manure. For example, biochar restrained the fungal class Eurotiomycetes by decreasing soil As and Cu availability, but manure inhibited Leotiomycetes mainly because of an increase in soil pH and a decrease in soil dissolved organic C. These suggest that both bacterial and fungal communities respond significantly to biochar and manure amendments in both bulk and rhizosphere soils, possibly because of their sensitive adaptation to variations in soil environmental factors, such as pH level and chemical element availability.展开更多
Vertical distribution of soil nematode communities under conventional tillage (CT),no-tillage (NT) and fallow field (FF) treatments in the Lower Reaches of the Liaohe River was investigated at six soil depths (0-5 cm,...Vertical distribution of soil nematode communities under conventional tillage (CT),no-tillage (NT) and fallow field (FF) treatments in the Lower Reaches of the Liaohe River was investigated at six soil depths (0-5 cm,5-15 cm,15-30 cm,30-50 cm,50-75 cm and 75-100 cm). The results show that total nematode abundance gradually decreases with depth,and the highest number of total nematodes is observed at 0-5 cm depth under NT and FF treatments. The number of fungivores and plant parasites is significantly higher under FF and NT treatments than under CT treatment at the 0-5 cm depth. There is significant soil depth effect on the abundances of bacterivores and omnivores-predators,which exhibits a similar trend to that of total nematodes; whereas,no significant tillage effect is found. Tillage effect on soil nematode communities can be reflected by values of relative tillage response of index V. Results of index V indicate that total nematodes,bacterivores,fungivores and plant parasites are mildly inhibited,and omnivores-predators is moderately inhibited under CT treatment; while,under FF treatment total nematodes is mildly,and fungivores and plant parasites are moderately stimulated,respectively.展开更多
Land use changes affect belowground ecosystems.During the past few decades,land use in Northeast China has changed considerably,and the area of paddy fields has increased rapidly from upland.In this study,soil charact...Land use changes affect belowground ecosystems.During the past few decades,land use in Northeast China has changed considerably,and the area of paddy fields has increased rapidly from upland.In this study,soil characteristics and soil biotic community in paddy fields with different years of rice cultivation were measured to examine the effects of land use change from upland to paddy fields on soil micro-food web.The upland maize fields were selected as control and the microbial community composition was characterized using phospholipid fatty acids(PLFAs) analysis.The microbial biomass(total PLFA),bacteria biomass,and fungi biomass were higher in the 20-40-year(late-stage) than 1-10-year(early-stage) paddy fields.The abundances of total nematodes and bacterivores were lower in the early-stage than late-stage paddy fields.The abundance of herbivores was the highest in the early-stage paddy fields but that of omnivore-predators was the highest in the late-stage paddy fields.Structural equation model indicated that soil food web was developed and structured after 20 years of paddy cultivation.Our results suggested that soil micro-food web may be a good indicator for soil development and stabilization of paddy fields following land use change.展开更多
Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attentio...Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention.Soil microorganisms have been proven to provide nutrients for specific plant growth,especially in nutrient-poor desert steppe ecosystems.However,the effects of N deposition on plant-soil microbial community interactions in such ecosystems remain poorly understood.To investigate these effects,we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb.desert steppe in Inner Mongolia Autonomous Region,China.Four N treatment levels(N0,N30,N50,and N100,corresponding to 0,30,50,and 100 kg N/(hm2•a),respectively)were applied to simulate atmospheric N deposition.The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants.N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in the desert steppe,and low and mediate N additions(N30 and N50)had a promoting effect on them.The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index.N deposition significantly affected the beta-diversity of plants and soil bacteria,but did not significantly affect fungal communities.In conclusion,N deposition led to co-evolution between desert steppe plants and soil bacterial communities,while fungal communities exhibited strong stability and did not undergo significant changes.These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.展开更多
Brazilian industry produces huge amounts of tannery sludge as residues,which is often disposed by landfilling or land application.However,consecutive amendment of such composted industrial wastes may cause shifts in s...Brazilian industry produces huge amounts of tannery sludge as residues,which is often disposed by landfilling or land application.However,consecutive amendment of such composted industrial wastes may cause shifts in soil microbial biomass(SMB) and enzyme activity.This study aimed to evaluate SMB and enzyme activity after 3-year consecutive composted tannery sludge(CTS) amendment in tropical sandy soils.Different amounts of CTS(0.0,2.5,5.0,10.0,and 20.0 t ha^(-1)) were applied to a sandy soil.The C and N contents of SMB,basal and substrate-induced respiration,respiratory quotient(qCO_2),and enzyme activities were determined in the soil samples collected after CTS amendment for 60 d at the third year.After 3 years,significant changes were found in soil microbial properties in response to different CTS amounts applied.The organic matter and Cr contents significantly increased with increasing CTS amounts.SMB and soil respiration peaked following amendment with 10.0 and 20.0 t ha-1 of CTS,respectively,while qCO_2was not significantly affected by CTS amendment.However,soil enzyme activity decreased significantly with increasing CTS amounts.Consecutive CTS amendment for 3 years showed inconsistent and contrasting effects on SMB and enzyme activities.The decrease in soil enzyme activities was proportional to a substantial increase in soil Cr concentration,with the latter exceeding the permitted concentrations by more than twofold.Thus,our results suggest that a maximum CTS quantity of 5.0 t ha^(-1) can be applied annually to tropical sandy soil,without causing potential risks to SMB and enzyme activity.展开更多
In natural systems heavy metals are present in very low concentrations (less than micro-molar), so precise measurement of the free metal ions is difficult. Recently, a new method has been developed called the Donnan m...In natural systems heavy metals are present in very low concentrations (less than micro-molar), so precise measurement of the free metal ions is difficult. Recently, a new method has been developed called the Donnan membrane technique (DMT). Several heavy metals could be measured simultaneously using this method. Furthermore, all the metals did not interfere with each other, and the balance between the measured system and the surrounding condition could not be disturbed. Improvements were made according to the internal condition. The free heavy metal ion concentrations were measured in different systems using the improved method, and satisfied results have been obtained.展开更多
Nitrogen(N)is one of the most limited nutrients of terrestrial ecosystems,whose losses are prevented in tightly coupled cycles in finely tuned systems.Global change-induced N enrichment through atmospheric deposition ...Nitrogen(N)is one of the most limited nutrients of terrestrial ecosystems,whose losses are prevented in tightly coupled cycles in finely tuned systems.Global change-induced N enrichment through atmospheric deposition and application of vast amounts of fertilizer are now challenging the terrestrial N cycle.Arbuscular mycorrhizal fungi(AMF)are known drivers of plant-soil nutrient fluxes,but a comprehensive assessment of AMF involvement in N cycling under global change is still lacking.Here,we simulated N enrichment by fertilization(low/high)in experimental grassland microcosms under greenhouse conditions in the presence or absence of AMF and continuously monitored different N pathways over nine months.We found that high N enrichment by fertilization decreased the relative abundance of legumes and the plant species dominating the plant community changed from grasses to forbs in the presence of AMF,based on aboveground biomass.The presence of AMF always maintained plant N:phosphorus(P)ratios between 14 and 16,no matter how the soil N availability changed.Shifts in plant N:P ratios due to the increased plant N and P uptake might thus be a primary pathway of AMF altering plant community composition.Furthermore,we constructed a comprehensive picture of AMF’s role in N cycling,highlighting that AMF reduced N losses primarily by mitigating N leaching,while N_(2)O emissions played a marginal role.Arbuscular mycorrhizal fungi reduced N_(2)O emissions directly through the promotion of N_(2)O-consuming denitrifiers.The underlying mechanism for reducing N leaching is mainly the AMF-mediated improved nutrient uptake and AMF-associated microbial immobilization.Our results indicate that synergies between AMF and other soil microorganisms cannot be ignored in N cycling and that the integral role of AMF in N cycling terrestrial ecosystems can buffer the upcoming global changes.展开更多
We used field experimental data to evaluate the ability of the agricultural production system model (APSIM) to simulate soil P availability,maize biomass and grain yield in response to P fertilizer applications on a f...We used field experimental data to evaluate the ability of the agricultural production system model (APSIM) to simulate soil P availability,maize biomass and grain yield in response to P fertilizer applications on a fluvo-aquic soil in the North China Plain.Crop and soil data from a 2-year experiment with three P fertilizer application rates(0,75 and 300 kg P_(2)O_(5) ha^(–1)) were used to calibrate the model.Sensitivity analysis was carried out to investigate the influence of APSIM SoilP parameters on the simulated P availability in soil and maize growth.Crop and soil P parameters were then derived by matching or relating the simulation results to observed crop biomass,yield,P uptake and Olsen-P in soil.The re-parameterized model was further validated against 2 years of independent data at the same sites.The re-parameterized model enabled good simulation of the maize leaf area index (LAI),biomass,grain yield,P uptake,and grain P content in response to different levels of P additions against both the calibration and validation datasets.Our results showed that APSIM needs to be re-parameterized for simulation of maize LAI dynamics through modification of leaf size curve and a reduction in the rate of leaf senescence for modern staygreen maize cultivars in China.The P concentration limits (maximum and minimum P concentrations in organs)at different stages also need to be adjusted.Our results further showed a curvilinear relationship between the measured Olsen-P concentration and simulated labile P content,which could facilitate the initialization of APSIM P pools in the NCP with Olsen-P measurements in future studies.It remains difficult to parameterize the APSIM SoilP module due to the conceptual nature of the pools and simplified conceptualization of key P transformation processes.A fundamental understanding still needs to be developed for modelling and predicting the fate of applied P fertilizers in soils with contrasting physical and chemical characteristics.展开更多
Fixed and random effect models were applied to a pseudo-panel data built of soil analysis reports from tobacco farms to analyze relationships between soil characteristics like soil organic matter (SOM) and soil nitrog...Fixed and random effect models were applied to a pseudo-panel data built of soil analysis reports from tobacco farms to analyze relationships between soil characteristics like soil organic matter (SOM) and soil nitrogen (N), phosphorous (P) and potassium (K) and to explore the potential for improving nutrients availability by increasing SOM content. These econometric models may account for unobserved specific characteristics such as location-specific characteristics, management strategies, farmers’ skills and preferences and environmental heterogeneity. Positive relationships were found between N, P and K availability and SOM. The random effect model reports a highly significant elasticity of N with respect to SOM of 0.75, meaning that an increase of 1% of SOM will increase soil N by 0.75%. Using this elasticity, the required SOM improvement of green manure was calculated at which costs of green manure would exactly equal benefits in terms of reduced N fertilizer use. Costs and benefits are equal if the SOM increases from 1.55% to 3.61%, which is barely achieved according to the literature. Hence, growing green manure crops to increase SOM and thereby N availability is not economically attractive. However, additional benefits may arise from SOM improvement and growing green manure crops.展开更多
Phosphorus(P)is a finite natural resource and is increasingly considered to be a challenge for global sustainability.Agriculture in China plays a key role in global sustainable P management.Rhizosphere and soil-based ...Phosphorus(P)is a finite natural resource and is increasingly considered to be a challenge for global sustainability.Agriculture in China plays a key role in global sustainable P management.Rhizosphere and soil-based P management are necessary for improving P-use efficiency and crop productivity in intensive agriculture in China.A previous study has shown that the future demand for phosphate fertilizer by China estimated by the LePA model(legacy phosphorus assessment model)can be greatly reduced by soil-based P management(the building-up and maintenance approach).The present study used the LePA model to predict the phosphate demand by China through combined rhizosphere and soil-based P management at county scale under four P fertilizer scenarios:(1)same P application rate as in 2012;(2)rate maintained same as 2012 in low-P counties or no P fertilizer applied in high-P counties until targeted soil Olsen-P(TPOlsen)level is reached,and then rate was the same as P-removed at harvest;(3)rate in each county decreased to1–7 kg ha^(-1) yr^(-1) after TPOlsen is reached in low-P counties,then increased by 0.1–9 kg ha^(-1) yr^(-1) until equal to P-removal;(4)rate maintained same as 2012 in low-P counties until TPOlsen is reached and then equaled to P-removal,while the rate in high-P counties is decreased to 1–7 kg ha^(-1) yr^(-1) until TPOlsen is reached and then increased by 0.1–9 kg ha^(-1) yr^(-1)until equal to P-removal.Our predictions showed that the total demand for P fertilizer by whole China was 693 Mt P2O5and according to scenario 4,P fertilizer could be reduced by 57.5%compared with farmer current practice,during the period 2013–2080.The model showed that rhizosphere P management led to a further 8.0%decrease in P fertilizer use compared with soil-based P management.The average soil Olsen-P level in China only needs to be maintained at 17 mg kg^(-1) to achieve high crop yields.Our results provide a firm basis for government to issue-relevant policies for sustainable P management in China.展开更多
Both straw incorporation and irrigation practices affect biological nitrogen(N)fixation(BNF),but it is still unclear how straw incorporation impacts BNF under continuous(CFI)or intermittent(IFI)flooding irrigation in ...Both straw incorporation and irrigation practices affect biological nitrogen(N)fixation(BNF),but it is still unclear how straw incorporation impacts BNF under continuous(CFI)or intermittent(IFI)flooding irrigation in a rice cropping system.A15N2-labeling chamber system was placed in a rice field to evaluate BNF with straw incorporation under CFI or IFI for 90 d.The nif H(gene encoding the nitrogenase reductase subunit)DNA and c DNA in soil were amplified using real-time quantitative polymerase chain reaction,and high-throughput sequencing was applied to the nif H gene.The total fixed N in the straw incorporation treatment was 14.3 kg ha^(-1)under CFI,being 116%higher than that under IFI(6.62 kg ha^(-1)).Straw incorporation and CFI showed significant interactive effects on the total fixed N and abundances of nif H DNA and c DNA.The increase in BNF was mainly due to the increase in the abundances of heterotrophic diazotrophs such as Desulfovibrio,Azonexus,and Azotobacter.These results indicated that straw incorporation stimulated BNF under CFI relative to IFI,which might ultimately lead to a rapid enhancement of soil fertility.展开更多
Black phosphorus(BP),as a rising star of 2D nanomaterials has drawn considerable attention in cancer therapy.However,the poor stability under ambient conditions limits their practical applications.Herein,a multiple su...Black phosphorus(BP),as a rising star of 2D nanomaterials has drawn considerable attention in cancer therapy.However,the poor stability under ambient conditions limits their practical applications.Herein,a multiple supramolecular assembly composed of adamantane-modified hyaluronic acid(HAADA),ferrocene-modified cinnamaldehyde(Fc-CA),guanidinium-functionalizedβ-cyclodextrin(Guano-CD),and black phosphorus(BP)nanosheets was successfully fabricated through cooperative host-vip and electrostatic interactions.Owing to the cooperative contribution of these building blocks,the obtained supramolecular assembly simultaneously possesses multiple functions including excellent stability,good biocompatibility and targeting property,and a high inhibition effect toward cancer cells.We believe that this work might provide new insights into designing a new generation of cancer theranostic protocols for potential clinical applications.展开更多
基金Supported by the National Council for Scientific and Technological Development,Brazil (No. 577148/2008-7)
文摘Land degradation causes great changes in the soil biological properties.The process of degradation may decrease soil microbial biomass and consequently decrease soil microbial activity.The study was conducted out during 2009 and 2010 at the four sites of land under native vegetation(NV),moderately degraded land(LDL),highly degraded land(HDL) and land under restoration for four years(RL) to evaluate changes in soil microbial biomass and activity in lands with different degradation levels in comparison with both land under native vegetation and land under restoration in Northeast Brazil.Soil samples were collected at 0-10 cm depth.Soil organic carbon(SOC),soil microbial biomass C(MBC) and N(MBN),soil respiration(SR),and hydrolysis of fluorescein diacetate(FDA) and dehydrogenase(DHA) activities were analyzed.After two years of evaluation,soil MBC,MBN,FDA and DHA had higher values in the NV,followed by the RL.The decreases of soil microbial biomass and enzyme activities in the degraded lands were approximately 8-10 times as large as those found in the NV.However,after land restoration,the MBC and MBN increased approximately 5-fold and 2-fold,respectively,compared with the HDL.The results showed that land degradation produced a strong decrease in soil microbial biomass.However,land restoration may promote short-and long-term increases in soil microbial biomass.
基金Project supported by the National High Technology Research and Development Program of China (863 Program)(Nos. 2002AA2Z4311 and 2002AA2Z4021), and the Soil Technology Group in Wageningen University, the Netherlands.
文摘Based on data from 10-year field experiments on residue/fertilizer management in the dryland farming region of northern China, Century model was used to simulate the site-specific ecosystem dynamics through adjustment of the model＇s parameters, and the applicability of the model to propose soil organic carbon （SOC） management temporally and spatially, in cases such as of tillage/residue/fertilization management options, was identified v/a scenario analysis.Results between simulations and actual measurements were in close agreement when appropriate applications of stover,manure and inorganic fertilizer were combined. Simulations of extreme C/N ratios with added organic materials tended to underestimate the measured effects. Scenarios of changed tillage methods, residue practices and fertilization options showed potential to maintain and enhance SOC in the long run, while increasing inorganic N slowed down the SOC turnover rate but did not create a net C sink without any organic C input. The Century model simulation showed a good relationship between annual C inputs to the soil and the rate of C sequestration in the top 20 cm layer and provided quantitative estimations of changes in parameters crucial for sustainable land use and management. Conservation tillage practices for sustainable land use should be integrated with residue management and appreciable organic and inorganic fertilizer application, adapted according to the local residue resource, soil fertility and production conditions. At least 50% residue return into the soil was needed annually for maintenance of SOC balance, and manure amendment was important for enhancement of SOC in small crop-livestock systems in which crop residue land application was limited.
基金the National Key Research and Development Program of China(No.2017YFD0801003)。
文摘Zero-valent iron amended biochar(ZVIB)has been proposed as a promising material in immobilizing heavy metals in paddy fields.In this study,the impacts of p H of ZVIB(p H 6.3 and p H 9.7)and watering management techniques(watering amount in the order of CON(control,5/72)>3/72>1-3/72>3/100>1/72,with 5/72,for example,representing irrigation given to 5 cm above soil surface in 72 hr regular interval)on As and Cd bioavailability for rice and its grain yield(Yield BR)were investigated in a pot experiment.Brown rice As(As BR)content was irrelative to the watering treatments,while significantly decreased(>50%)with the addition of both ZVIB materials.The diminutions of brown rice Cd(Cd BR)content as well as the Yield BR were highly dependent on both the soil amendment materials’p H and watering amount.Among all the watering treatments,3/72 treatment(15%less irrigation water than the CON)with ZVIB 6.3 amendment was the optimum fit for simultaneous reduction of As BR(50%)and Cd BR contents(19%)as well as for significant increment(12%)of the Yield BR.Although high pH(9.7)ZVIB application could also efficiently decrease As and Cd contents in brown rice,it might risk grain yield lost if appropriate(e.g.3/72 in our study)watering management technique was not chosen.Therefore,ZVIB would be an environmentally friendly option as an amendment material with proper selection of watering management technique to utilize As and Cd co-contaminated arable soils safely for paddy cultivation.
基金funded by the Inner Mongolia Autonomous Region’s Science and Technology Innovation Guidance Projectthe Hanggin Rear Banner Agricultural Extension Center, Inner Mongolia Autonomous Region, China for its help in this study
文摘Excessive fertilization combined with unreasonable irrigation in farmland of the Hetao Irrigation Area(HIR), China, has resulted in a large amount of nitrogen(N) losses and agricultural non-point source pollution.Application of soil amendments has become one of the important strategies for reducing N losses of farmland.However, there is still no systematic study on the effects of various soil amendments on N losses in the HIR.In this study, three types of soil amendments(biochar, bentonite and polyacrylamide) were applied in a maize–wheat rotation system in the HIR during 2015–2017.Yields of maize and wheat, soil NH3 volatilization, N2O emission and NO3– leaching were determined and soil N balance was estimated.The results showed that applications of biochar, bentonite and polyacrylamide significantly increased yields of maize by 9.2%, 14.3% and 13.3%, respectively, and wheat by 9.2%, 16.6% and 12.3%, respectively, compared with the control(fertilization alone).Applications of biochar, bentonite and polyacrylamide significantly reduced soil N leaching by 23.1%, 35.5% and 27.1%, soil NH3-N volatilization by 34.8%, 52.7% and 37.8%, and soil N surplus by 23.9%, 37.4% and 30.6%, respectively.Applications of bentonite and polyacrylamide significantly reduced N2O-N emissions from soil by 37.3% and 35.8%, respectively, compared with the control.Compared with application of biochar, applications of bentonite and polyacrylamide increased yields of maize and wheat by 5.1% and 3.5%, respectively.Our results suggest that soil amendments(bentonite and polyacrylamide) can play important roles in reducing N losses and increasing yield for the maize–wheat rotation system in the HIR, China.
基金supported by Patuakhali Science and Technology University (PSTU),Bangladesh
文摘Biochar has potentials for soil fertility improvement, climate change mitigation and environmental reclamation, and charred biomass can be deliberately incorporated into soil for long-term carbon stabilization and soil amendment. Many different methods have been used for biochar production ranging from laboratory to industrial scales. However, in countryside of developing countries, biomass is generally used for cooking but not charred. Biochar production techniques at farmer scale have remained poorly developed. We developed and tested biochar production kilns for farmers with a dimension of 50.8 cm × 38.1 cm （height × diameter）, using three different setups for optimizing oxygen （02） limitation and syngas circulation： airtight with no syngas circulation （Model I）, semi-airtight with external syngas circulation （Model II） and semi-airtight with internal syngas circulation （Model III）. A comparative assessment of these biochar production kiln models was made considering biochar pyrolysis time, fuel to biomass ratio, biochar to feedstock ratio and thermogravimetric index （TGI）. Among the models, the best quality biochar （TGI ---- 0.15） was obtained from Model I kiln taking the longest time for pyrolysis （12.5 h） and the highest amount of fuel wood （1.22 kg kg-1 biomass）. Model III kiln produced comparatively good quality biochar （TGI = 0.11）, but with less fuel wood requirement （0.33 kg kg-1 biomass） and shorter pyrolysis time （8.5 h）. We also tested Model III kiln in a three times larger size under two situations （steel kiln and pit kiln）. The biochar to feedstock ratio （0.38） and quality （TGI =0.14） increased slightly for the larger kilns. Quality of biochar was found to be mainly related to pyrolysis time. The costs for the biochar stove and pit kiln were US$ 65-77, while it was US$ 154 for the large size steel kiln. Model III kiln can potentially be used for both cooking and biochar production at farmer scale.
基金supported by the Inner Mongolia Autonomous Region Major Science and Technology Special Project (2019ZD001).
文摘Determining the distributions and sources of heavy metals in soils and assessing ecological risks are fundamental tasks in the control and management of pollution in mining areas.In this study,we selected 244 sampling sites around a typical lead(Pb)and zinc(Zn)mining area in eastern Inner Mongolia Autonomous Region of China and measured the content of six heavy metals,including cuprum(Cu),Zn,Pb,arsenic(As),cadmium(Cd),and chromium(Cr).The ecological risk of heavy metals was comprehensively evaluated using the Geo-accumulation index,Nemerow general pollution index,and potential ecological risk index.The heavy metals were traced using correlation analysis and principal component analysis.The results showed that the highest content of heavy metals was found in 0–5 cm soil layer in the study area.The average content of Zn,As,Pb,Cu,Cr,and Cd was 670,424,235,162,94,and 4 mg/kg,respectively,all exceeding the risk screening value of agricultural soil in China.The areas with high content of soil heavy metals were mainly distributed near the tailings pond.The study area was affected by a combination of multiple heavy metals,with Cd and As reaching severe pollution levels.The three pathways of exposure for carcinogenic and noncarcinogenic risks were ranked as inhalation>oral ingestion>dermal absorption.The heavy metals in the study area posed certain hazards to human health.Specifically,oral ingestion of these heavy metals carried carcinogenic risks for both children and adults,as well as noncarcinogenic risks for children.There were differences in the sources of different heavy metals.The tailings pond had a large impact on the accumulation of Cd,Zn,and Pb.The source of Cr was the soil parent material,the source of As was mainly the soil matrix,and the source of Cu was mainly the nearby Cu ore.The purpose of this study is to more accurately understand the extent,scope,and source of heavy metals pollution near a typical mining area,providing effective help to solve the problem of heavy metals pollution.
基金financially funded by the National Natural Science Foundation of China (Nos. 42277282 and41601334)the Public Welfare Technology Application Research Project of Zhejiang Province,China (NoLGF21D010002)+4 种基金the Key Research and Development Program of Zhejiang Province,China (No. 2020C01017)the State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-Products,Ningbo University,China (No. KF20190106)the Basic and Applied Basic Research Foundation of Guangdong Province,China (No. 2022A1515010861)the Shenzhen Science and Technology Program (No. JCYJ20220530150201003)the Young Teachers Team Project of Fundamental Research Funds for the Central Universities,Sun Yat-sen University,China (No. 22qntd2702)。
文摘Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, information on how bacterial and fungal communities in acidic bulk and rhizosphere soils respond to swine manure and its biochar is still lacking. In this study, biochar and swine manure were applied at two rates of 1.5 and 3 t ha-1in a rice-wheat rotation field to assess how soil characteristics, especially p H and chemical element availability, correlate to compositional variations of bacteria and fungi in bulk and rhizosphere soils. Our results showed that high rates of biochar and manure promoted the bacterial richness in bulk and rhizosphere soils by increasing soil pH and reducing soil arsenic(As) and copper(Cu) availability. Compared with soil As and Cu availability, soil p H had opposite effects on beta diversity of both the bacterial and fungal communities. Specifically, biochar and swine manure applications stimulated the bacterial classes Gemmatimonadetes, Deltaproteobacteria, and Gammaproteobacteria by increasing soil pH and decreasing soil available chemical elements. Opposite trends were observed in fungal communities responding to biochar and manure. For example, biochar restrained the fungal class Eurotiomycetes by decreasing soil As and Cu availability, but manure inhibited Leotiomycetes mainly because of an increase in soil pH and a decrease in soil dissolved organic C. These suggest that both bacterial and fungal communities respond significantly to biochar and manure amendments in both bulk and rhizosphere soils, possibly because of their sensitive adaptation to variations in soil environmental factors, such as pH level and chemical element availability.
基金Under the auspices of Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-445)the Science and Technology Program of Liaoning Province (No. 2009403053)
文摘Vertical distribution of soil nematode communities under conventional tillage (CT),no-tillage (NT) and fallow field (FF) treatments in the Lower Reaches of the Liaohe River was investigated at six soil depths (0-5 cm,5-15 cm,15-30 cm,30-50 cm,50-75 cm and 75-100 cm). The results show that total nematode abundance gradually decreases with depth,and the highest number of total nematodes is observed at 0-5 cm depth under NT and FF treatments. The number of fungivores and plant parasites is significantly higher under FF and NT treatments than under CT treatment at the 0-5 cm depth. There is significant soil depth effect on the abundances of bacterivores and omnivores-predators,which exhibits a similar trend to that of total nematodes; whereas,no significant tillage effect is found. Tillage effect on soil nematode communities can be reflected by values of relative tillage response of index V. Results of index V indicate that total nematodes,bacterivores,fungivores and plant parasites are mildly inhibited,and omnivores-predators is moderately inhibited under CT treatment; while,under FF treatment total nematodes is mildly,and fungivores and plant parasites are moderately stimulated,respectively.
基金supported by the National Key Research & Development(R&D) Plan of China(No. 2016YFD0300204)the National Basic Research Program(973 Program) of China(No.2011CB100504)
文摘Land use changes affect belowground ecosystems.During the past few decades,land use in Northeast China has changed considerably,and the area of paddy fields has increased rapidly from upland.In this study,soil characteristics and soil biotic community in paddy fields with different years of rice cultivation were measured to examine the effects of land use change from upland to paddy fields on soil micro-food web.The upland maize fields were selected as control and the microbial community composition was characterized using phospholipid fatty acids(PLFAs) analysis.The microbial biomass(total PLFA),bacteria biomass,and fungi biomass were higher in the 20-40-year(late-stage) than 1-10-year(early-stage) paddy fields.The abundances of total nematodes and bacterivores were lower in the early-stage than late-stage paddy fields.The abundance of herbivores was the highest in the early-stage paddy fields but that of omnivore-predators was the highest in the late-stage paddy fields.Structural equation model indicated that soil food web was developed and structured after 20 years of paddy cultivation.Our results suggested that soil micro-food web may be a good indicator for soil development and stabilization of paddy fields following land use change.
基金the National Natural Science Foundation of China(31860136,31560156)the Basic Scientific Research Service Fee Project of Colleges and Universities of Inner Mongolia Autonomous Regionthe Graduate Scientific Research Innovation Project of Inner Mongolia Autonomous Region(B20210158Z).
文摘Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention.Soil microorganisms have been proven to provide nutrients for specific plant growth,especially in nutrient-poor desert steppe ecosystems.However,the effects of N deposition on plant-soil microbial community interactions in such ecosystems remain poorly understood.To investigate these effects,we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb.desert steppe in Inner Mongolia Autonomous Region,China.Four N treatment levels(N0,N30,N50,and N100,corresponding to 0,30,50,and 100 kg N/(hm2•a),respectively)were applied to simulate atmospheric N deposition.The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants.N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in the desert steppe,and low and mediate N additions(N30 and N50)had a promoting effect on them.The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index.N deposition significantly affected the beta-diversity of plants and soil bacteria,but did not significantly affect fungal communities.In conclusion,N deposition led to co-evolution between desert steppe plants and soil bacterial communities,while fungal communities exhibited strong stability and did not undergo significant changes.These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.
基金Supported by the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico,Brazil(No.302999/2011-6)the Fundacao de Amparo a Pesquisa do Estado do Piaui,Brazil(No.032/2011)
文摘Brazilian industry produces huge amounts of tannery sludge as residues,which is often disposed by landfilling or land application.However,consecutive amendment of such composted industrial wastes may cause shifts in soil microbial biomass(SMB) and enzyme activity.This study aimed to evaluate SMB and enzyme activity after 3-year consecutive composted tannery sludge(CTS) amendment in tropical sandy soils.Different amounts of CTS(0.0,2.5,5.0,10.0,and 20.0 t ha^(-1)) were applied to a sandy soil.The C and N contents of SMB,basal and substrate-induced respiration,respiratory quotient(qCO_2),and enzyme activities were determined in the soil samples collected after CTS amendment for 60 d at the third year.After 3 years,significant changes were found in soil microbial properties in response to different CTS amounts applied.The organic matter and Cr contents significantly increased with increasing CTS amounts.SMB and soil respiration peaked following amendment with 10.0 and 20.0 t ha-1 of CTS,respectively,while qCO_2was not significantly affected by CTS amendment.However,soil enzyme activity decreased significantly with increasing CTS amounts.Consecutive CTS amendment for 3 years showed inconsistent and contrasting effects on SMB and enzyme activities.The decrease in soil enzyme activities was proportional to a substantial increase in soil Cr concentration,with the latter exceeding the permitted concentrations by more than twofold.Thus,our results suggest that a maximum CTS quantity of 5.0 t ha^(-1) can be applied annually to tropical sandy soil,without causing potential risks to SMB and enzyme activity.
文摘In natural systems heavy metals are present in very low concentrations (less than micro-molar), so precise measurement of the free metal ions is difficult. Recently, a new method has been developed called the Donnan membrane technique (DMT). Several heavy metals could be measured simultaneously using this method. Furthermore, all the metals did not interfere with each other, and the balance between the measured system and the surrounding condition could not be disturbed. Improvements were made according to the internal condition. The free heavy metal ion concentrations were measured in different systems using the improved method, and satisfied results have been obtained.
基金supported by the National Natural Science Foundation of China(Nos.32101304 and 32160281)the Key Laboratory Project,Xinjiang,China(No.2021D04006)+1 种基金China Postdoctoral Science Foundation(No.2021M692707)supported by the Swiss National Science Foundation(No.31003A-166079)。
文摘Nitrogen(N)is one of the most limited nutrients of terrestrial ecosystems,whose losses are prevented in tightly coupled cycles in finely tuned systems.Global change-induced N enrichment through atmospheric deposition and application of vast amounts of fertilizer are now challenging the terrestrial N cycle.Arbuscular mycorrhizal fungi(AMF)are known drivers of plant-soil nutrient fluxes,but a comprehensive assessment of AMF involvement in N cycling under global change is still lacking.Here,we simulated N enrichment by fertilization(low/high)in experimental grassland microcosms under greenhouse conditions in the presence or absence of AMF and continuously monitored different N pathways over nine months.We found that high N enrichment by fertilization decreased the relative abundance of legumes and the plant species dominating the plant community changed from grasses to forbs in the presence of AMF,based on aboveground biomass.The presence of AMF always maintained plant N:phosphorus(P)ratios between 14 and 16,no matter how the soil N availability changed.Shifts in plant N:P ratios due to the increased plant N and P uptake might thus be a primary pathway of AMF altering plant community composition.Furthermore,we constructed a comprehensive picture of AMF’s role in N cycling,highlighting that AMF reduced N losses primarily by mitigating N leaching,while N_(2)O emissions played a marginal role.Arbuscular mycorrhizal fungi reduced N_(2)O emissions directly through the promotion of N_(2)O-consuming denitrifiers.The underlying mechanism for reducing N leaching is mainly the AMF-mediated improved nutrient uptake and AMF-associated microbial immobilization.Our results indicate that synergies between AMF and other soil microorganisms cannot be ignored in N cycling and that the integral role of AMF in N cycling terrestrial ecosystems can buffer the upcoming global changes.
基金funded by the National Natural Science Program of China(2022YFD1900300)the China Scholarship Council(CSC)through the CSC-CSIRO(Commonwealth Scientific and Industrial Research Organisation)Joint Ph D Program,the Zhumadian Major Scientific and Technological Innovation Project,China(170109564016)the Huanghuai University Scientific Research Foundation,China(502310020017)。
文摘We used field experimental data to evaluate the ability of the agricultural production system model (APSIM) to simulate soil P availability,maize biomass and grain yield in response to P fertilizer applications on a fluvo-aquic soil in the North China Plain.Crop and soil data from a 2-year experiment with three P fertilizer application rates(0,75 and 300 kg P_(2)O_(5) ha^(–1)) were used to calibrate the model.Sensitivity analysis was carried out to investigate the influence of APSIM SoilP parameters on the simulated P availability in soil and maize growth.Crop and soil P parameters were then derived by matching or relating the simulation results to observed crop biomass,yield,P uptake and Olsen-P in soil.The re-parameterized model was further validated against 2 years of independent data at the same sites.The re-parameterized model enabled good simulation of the maize leaf area index (LAI),biomass,grain yield,P uptake,and grain P content in response to different levels of P additions against both the calibration and validation datasets.Our results showed that APSIM needs to be re-parameterized for simulation of maize LAI dynamics through modification of leaf size curve and a reduction in the rate of leaf senescence for modern staygreen maize cultivars in China.The P concentration limits (maximum and minimum P concentrations in organs)at different stages also need to be adjusted.Our results further showed a curvilinear relationship between the measured Olsen-P concentration and simulated labile P content,which could facilitate the initialization of APSIM P pools in the NCP with Olsen-P measurements in future studies.It remains difficult to parameterize the APSIM SoilP module due to the conceptual nature of the pools and simplified conceptualization of key P transformation processes.A fundamental understanding still needs to be developed for modelling and predicting the fate of applied P fertilizers in soils with contrasting physical and chemical characteristics.
文摘Fixed and random effect models were applied to a pseudo-panel data built of soil analysis reports from tobacco farms to analyze relationships between soil characteristics like soil organic matter (SOM) and soil nitrogen (N), phosphorous (P) and potassium (K) and to explore the potential for improving nutrients availability by increasing SOM content. These econometric models may account for unobserved specific characteristics such as location-specific characteristics, management strategies, farmers’ skills and preferences and environmental heterogeneity. Positive relationships were found between N, P and K availability and SOM. The random effect model reports a highly significant elasticity of N with respect to SOM of 0.75, meaning that an increase of 1% of SOM will increase soil N by 0.75%. Using this elasticity, the required SOM improvement of green manure was calculated at which costs of green manure would exactly equal benefits in terms of reduced N fertilizer use. Costs and benefits are equal if the SOM increases from 1.55% to 3.61%, which is barely achieved according to the literature. Hence, growing green manure crops to increase SOM and thereby N availability is not economically attractive. However, additional benefits may arise from SOM improvement and growing green manure crops.
基金supported by the Double First-Class Financial Capital in China(NDYB2018-4)the Scientific Research Start-up Fund of the Autonomous Region Human Resources and Social Security Department in 2018,China(for Haigang Li)+1 种基金the Project of Grassland Talent,China(for Haigang Li)the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-328017493/GRK 2366(International Research Training Group“Adaptation of Maize-based Food–Feed–Energy Systems to Limited Phosphate Resources”)。
文摘Phosphorus(P)is a finite natural resource and is increasingly considered to be a challenge for global sustainability.Agriculture in China plays a key role in global sustainable P management.Rhizosphere and soil-based P management are necessary for improving P-use efficiency and crop productivity in intensive agriculture in China.A previous study has shown that the future demand for phosphate fertilizer by China estimated by the LePA model(legacy phosphorus assessment model)can be greatly reduced by soil-based P management(the building-up and maintenance approach).The present study used the LePA model to predict the phosphate demand by China through combined rhizosphere and soil-based P management at county scale under four P fertilizer scenarios:(1)same P application rate as in 2012;(2)rate maintained same as 2012 in low-P counties or no P fertilizer applied in high-P counties until targeted soil Olsen-P(TPOlsen)level is reached,and then rate was the same as P-removed at harvest;(3)rate in each county decreased to1–7 kg ha^(-1) yr^(-1) after TPOlsen is reached in low-P counties,then increased by 0.1–9 kg ha^(-1) yr^(-1) until equal to P-removal;(4)rate maintained same as 2012 in low-P counties until TPOlsen is reached and then equaled to P-removal,while the rate in high-P counties is decreased to 1–7 kg ha^(-1) yr^(-1) until TPOlsen is reached and then increased by 0.1–9 kg ha^(-1) yr^(-1)until equal to P-removal.Our predictions showed that the total demand for P fertilizer by whole China was 693 Mt P2O5and according to scenario 4,P fertilizer could be reduced by 57.5%compared with farmer current practice,during the period 2013–2080.The model showed that rhizosphere P management led to a further 8.0%decrease in P fertilizer use compared with soil-based P management.The average soil Olsen-P level in China only needs to be maintained at 17 mg kg^(-1) to achieve high crop yields.Our results provide a firm basis for government to issue-relevant policies for sustainable P management in China.
基金supported by the National Natural Science Foundation of China(Nos.42177333 and 31870500)the National Special Program for Key Basic Research of the Ministry of Science and Technology of China(No.2015FY110700)the Jiangsu Agriculture Science and Technology Innovation Fund,China(No.JASTIFCX(20)2003)。
文摘Both straw incorporation and irrigation practices affect biological nitrogen(N)fixation(BNF),but it is still unclear how straw incorporation impacts BNF under continuous(CFI)or intermittent(IFI)flooding irrigation in a rice cropping system.A15N2-labeling chamber system was placed in a rice field to evaluate BNF with straw incorporation under CFI or IFI for 90 d.The nif H(gene encoding the nitrogenase reductase subunit)DNA and c DNA in soil were amplified using real-time quantitative polymerase chain reaction,and high-throughput sequencing was applied to the nif H gene.The total fixed N in the straw incorporation treatment was 14.3 kg ha^(-1)under CFI,being 116%higher than that under IFI(6.62 kg ha^(-1)).Straw incorporation and CFI showed significant interactive effects on the total fixed N and abundances of nif H DNA and c DNA.The increase in BNF was mainly due to the increase in the abundances of heterotrophic diazotrophs such as Desulfovibrio,Azonexus,and Azotobacter.These results indicated that straw incorporation stimulated BNF under CFI relative to IFI,which might ultimately lead to a rapid enhancement of soil fertility.
基金supported by the Program for improving the Scientific Research Ability of Youth Teachers of Inner Mongolia Agricultural University(No.BR220140)the National Natural Science Foundation of China(No.52263013)+2 种基金the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2021MS02023)the Grassland Talents program of Inner Mongolia Autonomous Regionthe Program of Higher-level Talents of Inner Mongolia Agricultural University(No.NDGCC2016-21)。
文摘Black phosphorus(BP),as a rising star of 2D nanomaterials has drawn considerable attention in cancer therapy.However,the poor stability under ambient conditions limits their practical applications.Herein,a multiple supramolecular assembly composed of adamantane-modified hyaluronic acid(HAADA),ferrocene-modified cinnamaldehyde(Fc-CA),guanidinium-functionalizedβ-cyclodextrin(Guano-CD),and black phosphorus(BP)nanosheets was successfully fabricated through cooperative host-vip and electrostatic interactions.Owing to the cooperative contribution of these building blocks,the obtained supramolecular assembly simultaneously possesses multiple functions including excellent stability,good biocompatibility and targeting property,and a high inhibition effect toward cancer cells.We believe that this work might provide new insights into designing a new generation of cancer theranostic protocols for potential clinical applications.
