Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing...Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.展开更多
Due to continuous decreases in arable land area and continuous population increases,Chinese soil scientists face great challenges in meeting food demands,mitigating adverse environmental impacts,and sustaining or enha...Due to continuous decreases in arable land area and continuous population increases,Chinese soil scientists face great challenges in meeting food demands,mitigating adverse environmental impacts,and sustaining or enhancing soil productivity under intensive agriculture.With the aim of promoting the application of soil science knowledge,this paper reviews the achievements of Chinese scientists in soil resource use and management,soil fertility,global change mitigation and soil biology over the last 30 years.During this period,soil resource science has provided essential support for the use and exploitation of Chinese soil resources,and has itself developed through introduction of new theories such as Soil Taxonomy and new technologies such as remote sensing.Soil fertility science has contributed to the alleviation and elimination of impeding physical and chemical factors that constrain availability of essential nutrients and water in soils,the understanding of nutrient cycling in agroecosystems,and the increase in nutrient use efficiency for sustainable crop production.Chinese soil scientists have contributed to the understanding of the cropland's role in global change,particularly to the understanding of methane and nitrous oxide emission from rice fields and the effect of elevated carbon dioxide and ozone on rice-wheat system.Soil biology research has progressed in biological N fixation,distribution of fauna in Chinese soils,and bioremediation of polluted soils.A new generation of soil scientists has arisen in the last three decades.The gaps between research and application in these soil science fields are also discussed.展开更多
Soils are a valuable resource with life activity in terrestrial ecosystem,and soil health and its sustainable management are becoming a major focus of global concern.A healthy soil is a“harmonious social system”,whi...Soils are a valuable resource with life activity in terrestrial ecosystem,and soil health and its sustainable management are becoming a major focus of global concern.A healthy soil is a“harmonious social system”,which should have good structure,functional state,and buffering performance to maintain the dynamic balance of soil ecosystem.Soil health has become the frontier of soil science.The development of theoretical and practical approaches for soil health evaluation and management is urgently needed.Therefore,further research is needed to develop new techniques and methods for soil health research,construct soil health index and evaluation system,clarify the mechanism and spatial-temporal pattern of soil health conservation,and establish soil health protection and cultivation technology,which would provide scientific and technological support for soil resource protection and sustainable utilization.展开更多
New pollutants have become a significant concern in China's efforts toward ecological and environmental protection.Trichloromethane(TCM,CHCl_3),one of these new pollutants,is primarily released into soil and groun...New pollutants have become a significant concern in China's efforts toward ecological and environmental protection.Trichloromethane(TCM,CHCl_3),one of these new pollutants,is primarily released into soil and groundwater through various industrial activities.Over the past four decades,researchers have consistently focused on the remediation of TCM-contaminated soil and groundwater using microorganisms and iron-based materials,which hold significant potential for practical application.Understanding the remediation process and the factors influencing TCM degradation through these two methods is crucial for advancing both theoretical research and practical implementation.This review focuses on the degradation mechanisms of TCM in soil and groundwater by microorganisms and iron-based materials.It summarizes the active microorganisms and modified iron-based materials with high TCM degradation capabilities,discusses enhancement measures for both methods in the remediation process,and finally,outlines the challenges faced by these methods.The goal is to provide theoretical references for efficient remediation of TCM-contaminated soil and groundwater.展开更多
Rice seedling blight,caused by various fungi,including Fusarium oxysporum,poses a severe threat to rice production.As awareness grows regarding the environmental and safety hazards associated with the application of f...Rice seedling blight,caused by various fungi,including Fusarium oxysporum,poses a severe threat to rice production.As awareness grows regarding the environmental and safety hazards associated with the application of fungicides for managing rice seedling blight,there has been a shift in focus towards biological control agents.In this study,we isolated biocontrol bacteria from paddy fields that significantly inhibited the growth of F.oxysporum in vitro and identified the strains as Bacillus amyloliquefaciens T40 and Bacillus pumilus T208.Additionally,our findings indicated that the combined application of these Bacillus strains in soil was more effective in reducing the incidence of rice seedling blight than their individual use.Analysis of 16S and internal transcribed spacer rRNA gene sequencing data revealed that the mixture of the T40 and T208 strains exhibited the lowest average clustering coefficients,which were negatively correlated with the biomass of F.oxysporum-inoculated rice seedlings.Furthermore,this mixture led to higher stochastic assembly(average|βNTI|<2)and reduced selection pressures on rice rhizosphere bacteria compared with individual strain applications.The mixture of the T40 and T208 strains also significantly increased the expression of defense-related genes.In conclusion,the mixture of the T40 and T208 strains effectively modulates microbial community structures,enhances microbial network stability,and boosts the resistance against rice seedling blight.Our study supports the development and utilization of biological resources for crop protection.展开更多
Soil bioaccessible and labile As were extracted using in vitro,diffusive gradients in thin films(DGT)and chemical extraction methods.The results showed that As(Ⅲ)was readily converted to As(Ⅴ)in the soils,which was ...Soil bioaccessible and labile As were extracted using in vitro,diffusive gradients in thin films(DGT)and chemical extraction methods.The results showed that As(Ⅲ)was readily converted to As(Ⅴ)in the soils,which was promoted by alkaline conditions and higher content of easily reducible Mn.As(Ⅴ)was not readily reduced to As(Ⅲ)in these soils.The effect of soil pH on bioaccessible As content by in vitro method and labile As content by DGT methodwere inconsistent among different soils due to the coincidence of As(Ⅲ)and As(Ⅴ),with As(Ⅲ)being more readily mobilized in acidic environment while the opposite was true for As(Ⅴ).The labile As extracted by phosphate was significantly correlated with that extracted by in vitro method,while the labile As extracted by the DGT was correlated with that extracted by the CaCl_(2) method.The labile As extracted by the DGT was much lower than that by the in vitro and phosphate methods.The in vitro and phosphate methods extracted As in soils which is tightly bound to Fe oxides through dissolution,complexation and ion exchange.In contrast,the DGT method relied on the adsorption of soil labile As onto ZrO-based binding layer.The higher contents of soil Fe oxides and greater adsorption capacity for As led to the lower content of As measured by the DGT method.In conclusion,the in vitro and phosphate extraction are potential to be used to predict soil bioaccessible As.The DGT method is more suitable for ecological risk prediction.展开更多
Winter irrigation is a crucial measure for preventing farmland salinity in arid inland regions.However,given the relatively complex process of salt leaching under the influence of freezing and thawing,present salinity...Winter irrigation is a crucial measure for preventing farmland salinity in arid inland regions.However,given the relatively complex process of salt leaching under the influence of freezing and thawing,present salinity management has led to soil quality deterioration in the irrigation areas in Northwest China.To better understand this process,a field experiment was conducted in Huangyang Town,Wuwei City,Gansu Province,China to simulate the evolution of soil profile salinity and alkalinity in a typical oasis farmland under 3-year regular barley planting,using a local prevailing water-salt management mode of drip irrigation for the growing period and winter irrigation for the fallow period.This study investigated the impact of freezing on salt leaching by comparing the soil profile water,heat,and salt movements under different winter irrigation quotas.Compared to no winter irrigation,a reduction in the winter irrigation quota from the standard one to a halved one led to a transition from a sink of 11.05% by salt leaching to a source of 13.75% by salt addition.This means that overwintering soil freezing,especially in oases with deep groundwater tables,can worsen root zone salinization caused by a deficit winter irrigation,through freezing-induced root zone soil water and salt return.Furthermore,dry saline soil dominated by sulfate is at the risk of soil alkalization when freezing-induced oversaturation of solute concentration leads to significant salt precipitation.These findings are crucial for understanding the mechanisms behind the increasing secondary salinization caused by unsustainable winter irrigation in oasis irrigation areas.展开更多
Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental...Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental understanding of the underlying mechanisms that control fine root plasticity.The objective of this study was to determine the influence of soil moisture changes on fine root dynamics and morphology of European beech(Fagus sylvatica L.).We conducted a 30-month study of fine root traits,i.e.,fine root biomass(FRB),productivity,mortality,turnover,specific root length(SRL),specific root area(SRA),and root tip frequency(RTF),along a soil moisture gradient from dry,intermediate,and wet conditions in a near-natural mature beech forest.Sequential root coring with accompanying soil measurements was carried out at three study sites reflecting the gradient in soil water availability.For most fine root traits,we found significant differences between the upper 10 cm and lower soil depths.FRB showed significant differences between study sites,with the lowest FRB at the dry site.However,productivity,turnover,SRL,SRA,and RTF showed no significant differences between sites,but a high variability between seasons,suggesting an adaptation to short-term fluctuations but not to long-term gradients in soil water content(SWC).Linear mixed models revealed that decreasing SWC led to a significant increase in SRL,SRA,and RTF(standardized coefficients:-1.0±0.46,-1.1±0.46,and-1.1±0.43,respectively).Our observations indicate an adaptation strategy of beech to low availability of soil water and drought by forming thin absorptive roots and by maintaining a high seasonal plasticity to tolerate fluctuations in soil moisture.By highlighting the belowground morphological adaptations of mature forests to low soil water availability,our results provide novel insights into the structure and dynamics of forest ecosystem adaptations to climate change.展开更多
Diazotrophs make important contributions to nitrogen(N) inputs in agricultural ecosystems. However, strong evidence of the effects of conservation tillage(CT) on the coexistence and assembly of soil diazotrophic commu...Diazotrophs make important contributions to nitrogen(N) inputs in agricultural ecosystems. However, strong evidence of the effects of conservation tillage(CT) on the coexistence and assembly of soil diazotrophic community and related mechanisms is lacking. Here, a long-term experiment was conducted to study the impacts of CT on the coexistence and assembly patterns of soil diazotrophic community in Lishu County, Jilin Province, North China. Compared to traditional tillage(control, CK), CT significantly reduced both the N fixation rate in top 0–10 cm soil and the alpha diversity of diazotrophic community while increasing the density of diazotrophic and overall bacterial communities. Conservation tillage also reduced the competitive relationships within the diazotrophic community and enhanced network stability. Furthermore, diazotroph assembly was dominated by deterministic processes(relative influence =68.63%) under CK and stochastic processes(relative influence = 58.82%) under CT. Soil depth and total N(TN) were identified as crucial predictors shaping the assembly processes of diazotrophic community under different tillage practices. The relative influence of stochastic processes on diazotrophic community under CT varied more significantly with increasing soil depth. Overall, tillage practice and soil depth had significant influences on the coexistence and assembly processes of soil diazotrophic community. Moreover, long-term CT may impact the selection of N fixation agents and the specific taxa associated with N fixers. Our results indicated that in CT systems, relatively sufficient nutrient availability led to a reduction in interspecies competition, an increase in network stability, and a greater influence of stochastic processes on community assembly. These findings may help us better understand biological N fixation in sustainable agricultural systems.展开更多
Green prevention and control management of soil-borne fungal diseases is a hot topic in agriculture,ecology,and the environment.It is an important way to effectively prevent and control soil-borne fungal diseases,solv...Green prevention and control management of soil-borne fungal diseases is a hot topic in agriculture,ecology,and the environment.It is an important way to effectively prevent and control soil-borne fungal diseases,solve soil degradation caused by continuous cropping obstacles,and fulfill the sustainable development of agriculture through revealing the mechanisms of functional substances to develop highly effective soil amendments.Humic acid shows an inhibitory effect on soil-borne pathogenic fungi,such as Fusarium oxysporum,Choanephora cucurbitarum,and Rhizoctonia solani,with the inhibition rate exceeding 80%.The molecular and elemental composition and contents of–COOH,phenolic C,methoxy group C,carboxyl C,aromatic C–O,anomeric C,and other functional groups of humic acid have been inferred to be responsible for its inhibitory effects on pathogenic fungi in previous research.The inhibitory mechanisms mainly include cell physiological morphology,biochemical process reactions,and molecular signal transduction.This review systematically summarizes the chemical structure,fungistatic effects,variable characteristics,and inhibitory mechanisms of humic acid,aiming to provide a theoretical basis for the development of green and efficient prevention and control technologies for soil-borne fungal diseases.展开更多
Straw return is the main practice used to increase soil organic matter(SOM)in agricultural ecosystems.To increase the efficiency of straw conversion to SOM,a large number of microbial inoculants have been developed.Ho...Straw return is the main practice used to increase soil organic matter(SOM)in agricultural ecosystems.To increase the efficiency of straw conversion to SOM,a large number of microbial inoculants have been developed.However,their effects are poor because of the complex water and temperature conditions,especially under sodic conditions.Small molecules can rapidly shift soil microbial communities and improve their ability to transform exogenous organic matter into SOM,providing a new direction for promoting high-efficiency straw conversion into SOM.In this study,we conducted a^(13)C-labeled straw degradation experiment using small molecules derived from lignin(LSMs)and humus(HSMs)as activators,investigating their effects on the microbial communities and formation of newly formed mineral-associated(^(13)C-MAOM)and particulate(^(13)C-POM)organic matter from^(13)C-labeled straw in both sodic and non-sodic soils.The^(13)C-labeled straw was mainly converted into^(13)C-MAOM,accounting for 73.97%–92.67%of the newly formed SOM.Biopolymer-derived small molecules decreased the exchangeable sodium percentage(ESP),but increased contents of^(13)C-MAOM and^(13)C-POM by shifting microbial communities,strengthening microbial cross-trophic interactions,enhancing enzyme activities,and increasing microbial residues in both soils.Addition of HSMs had greater impacts on^(13)C-MAOM formation than LSM addition.The^(13)C-MAOM and^(13)C-POM formation negatively correlated with ESP,but positively correlated with microbial cross-trophic interactions and enzyme activities in both soils.Our results suggest that biopolymer-derived small molecules promote^(13)C-MAOM and^(13)C-POM formation associated with microbial cross-trophic interactions between protistan predators and primary decomposers.Our study provides scientific support for future attempts to stimulate microbial cross-trophic interactions for boosting SOM accumulation under stressed conditions.展开更多
Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of...Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of soil C:N:P ratios are still poorly understood on the Qinghai-Tibetan Plateau of China.In this study,we therefore combined data of the geography,climate,soil properties,and vegetation characteristics from 319 sites across the plateau to investigate their relationships with the horizontal and vertical patterns of SOC,TN,and TP concentrations and their stoichiometric ratios(C:N and N:P).We observed higher SOC(30.5–46.8 mg g^(-1)),TN(2.4–3.4 mg g^(-1)),C:N(14.7–18.0),and N:P(6.9–8.0)in alpine meadows,forests,and shrublands and higher TP(1.6 mg g^(-1))in croplands.Overall,SOC,TN,TP,C:N,and N:P showed decreasing trends(by 67%,64%,19%,12%,and 54%,respectively)along the whole soil profile(0–100 cm).Soil cation exchange capacity and bulk density were the stronger environmental drivers of SOC and TN.Soil TP showed latitudinal and longitudinal increasing trends in all soil layers.Soil properties explained most of the variations in SOC(67%–90%),TN(67%–87%),C:N(61%–89%),and N:P(64%–85%),with increasing impacts along the soil profile.Geography and climate influenced soil TP directly and indirectly through their impacts on soil properties,with geography being the predominant driver(46%–65%)along the soil profile.The variation in soil C:N was mostly driven by SOC and TN,and the direct and indirect effects of the environmental factors were relatively weak.Geography,climate,soil properties,and vegetation characteristics indirectly impacted soil N:P through their impacts on TN and TP in all the soil layers.Altogether,our findings illuminate the relative contributions of geography,climate,soil properties,and vegetation characteristics to soil C:N and N:P,thus enhancing our understanding of C,N,and P cycling across the Qinghai-Tibetan Plateau.展开更多
Dear Editor,Plastics have been ubiquitous in the environment due to their high amounts of production and application(Geyer et al.,2017).In 2021,annual global plastic production increased to 39.07 billion tons(Rede et ...Dear Editor,Plastics have been ubiquitous in the environment due to their high amounts of production and application(Geyer et al.,2017).In 2021,annual global plastic production increased to 39.07 billion tons(Rede et al.,2023).Plastics undergo weathering,photolysis,and other environmental effects and form emerging contaminants with small particle sizes that can easily migrate,i.e.,microplastics(MPs,<5 mm)(Auta et al.,2017).展开更多
Soil erosion is the primary factor causing the loss of soil resources and land degradation.Clarifying the current status of soil erosion in China and the characteristics of future changes under different pathways of d...Soil erosion is the primary factor causing the loss of soil resources and land degradation.Clarifying the current status of soil erosion in China and the characteristics of future changes under different pathways of development is important to the global management of soil resources,food security,and ecosystem services.We used the revised universal soil loss equation and the most recent and reliable soil and environmental data to characterize soil erosion in China at present and under typical Shared Socioeconomic Pathways and Representative Concentration Pathways(i.e.,SSP1–2.6 and SSP5–8.5)in the medium-and long-term future(2050 and 2100).The current average rate of soil erosion in China was 14.78 t ha^(-1)yr^(-1),with a total amount of about 14.0 Pg yr^(-1).The amount of total erosion increased by 5.0%,10.8%,9.9%,and 25.9%for scenarios 2050_SSP1–2.6,2050_SSP5–8.5,2100_SSP1–2.6,and 2100_SSP5–8.5,respectively,compared to the baseline amount in 2010.The contribution of climate change and land use to the increase in erosion ranged from 9.5%to 31.5%and-6.95%to-1.78%,respectively,with the contribution of climate change about 2.36-to 7.54-fold larger than the contribution of land use.Converting arable barren land into forest and grassland or adopting conservation tillage practices for farmland,could nevertheless effectively offset the increase in erosion under the four future scenarios.This study provides data and a scientific basis for managing soil erosion in China and provides a useful reference for conserving global land resources and formulating policies to cope with climatic and environmental changes.展开更多
Accurately mapping the spatial distribution of soil organic carbon(SOC)is crucial for guiding agricultural management and improving soil carbon sequestration,especially in fragmented agricultural landscapes.Although r...Accurately mapping the spatial distribution of soil organic carbon(SOC)is crucial for guiding agricultural management and improving soil carbon sequestration,especially in fragmented agricultural landscapes.Although remote sensing provides spatially continuous environmental information about heterogeneous agricultural landscapes,its relationship with SOC remains unclear.In this study,we hypothesized that multi-category remote sensing-derived variables can enhance our understanding of SOC variation within complex landscape conditions.Taking the Qilu Lake watershed in Yunnan,China,as a case study area and based on 216 topsoil samples collected from irrigation areas,we applied the extreme gradient boosting(XGBoost)model to investigate the contributions of vegetation indices(VI),brightness indices(BI),moisture indices(MI),and spectral transformations(ST,principal component analysis and tasseled cap transformation)to SOC mapping.The results showed that ST contributed the most to SOC prediction accuracy,followed by MI,VI,and BI,with improvements in R2 of 29.27,26.83,19.51,and 14.43%,respectively.The dominance of ST can be attributed to the fact that it contains richer remote sensing spectral information.The optimal SOC prediction model integrated soil properties,topographic factors,location factors,and landscape metrics,as well as remote sensing-derived variables,and achieved RMSE and MAE of 15.05 and 11.42 g kg-1,and R2 and CCC of 0.57 and 0.72,respectively.The Shapley additive explanations deciphered the nonlinear and threshold effects that exist between soil moisture,vegetation status,soil brightness and SOC.Compared with traditional linear regression models,interpretable machine learning has advantages in prediction accuracy and revealing the influences of variables that reflect landscape characteristics on SOC.Overall,this study not only reveals how remote sensing-derived variables contribute to our understanding of SOC distribution in fragmented agricultural landscapes but also clarifies their efficacy.Through interpretable machine learning,we can further elucidate the causes of SOC variation,which is important for sustainable soil management and agricultural practices.展开更多
Heavy metals in variable charge soil are highly bioavailable and easy to transfer into plants. Since it is impossible to completely eliminate rice planting on contaminated soils, some remediation and mitigation techni...Heavy metals in variable charge soil are highly bioavailable and easy to transfer into plants. Since it is impossible to completely eliminate rice planting on contaminated soils, some remediation and mitigation techniques are necessary to reduce metal bioavailability and uptake by rice. This pot experiment investigated the effects of seven amendments on the growth of rice and uptake of heavy metals from a paddy soil that was contaminated by copper and cadmium. The best results were from the application of limestone that increased grain yield by 12.5-16.5 fold, and decreased Cu and Cd concentrations in grain by 23.0%--50.4%. Application of calcium magnesium phosphate, calcium silicate, pig manure, and peat also increased the grain yield by 0.3-15.3 fold, and effectively decreased the Cu and Cd concentrations in grain. Cd concentration in grain was slightly reduced in the treatments of Chinese milk vetch and zinc sulfate. Concentrations of Cu and Cd in grain and straw were dependent on the available Cu and Cd in the soils, and soil available Cu and Cd were significantly affected by the soil pH.展开更多
The liming potential of some crop residues and their biochars on an acid Ultisol was investigated using incubation experiments. Rice hulls showed greater liming potential than rice hull biochar, while soybean and pea ...The liming potential of some crop residues and their biochars on an acid Ultisol was investigated using incubation experiments. Rice hulls showed greater liming potential than rice hull biochar, while soybean and pea straws had less liming potential than their biochars. Due to their higher alkalinity, biochars from legume materials increased soil pH much compared to biochars from non-legume materials. The alkalinity of biochars was a key factor affecting their liming potential, and the greater alkalinity of biochars led to greater reductions in soil acidity. The incorporation of biochars decreased soil exchangeable acidity and increased soil exchangeable base cations and base saturation, thus improving soil fertility.展开更多
A long-term experiment was conducted to investigate how long-term fertilization and rice straw incorporation into soil affect soil glomalin, C and N. The combined application of chemical fertilizer and straw resulted ...A long-term experiment was conducted to investigate how long-term fertilization and rice straw incorporation into soil affect soil glomalin, C and N. The combined application of chemical fertilizer and straw resulted in a significant increase in both soil easily extractable glomalin (EEG) and total glomalin (TG) concentrations, as compared with application of only chemical fertilizer or no fertilizer application. The EEG and TG concentrations of the NPKS (nitrogen, phosphorus, and potassium fertilizer application + rice straw return) plot were 4.68% and 5.67% higher than those of the CK (unfertilized control) plot, and 9.87% and 6.23% higher than those of the NPK (nitrogen, phosphorus, and potassium fertilizer applied annually) plot, respectively. Application of only chemical fertilizer did not cause a statistically significant change of soil glomalin compared with no fertilizer application. The changes of soil organic C (SOC) and total N (TN) contents demonstrated a similar trend to soil glomalin in these plots. The SOC and TN contents of NPKS plot were 15.01% and 9.18% higher than those of the CK plot, and 8.85% and 14.76% higher than those of the NPK plot, respectively. Rice straw return also enhanced the contents of microbial biomass C (MBC) and microbial biomass N (MBN) in the NPKS plot by 7.76% for MBC and 31.42% for MBN compared with the CK plot, and 12.66% for MBC and 15.07% for MBN compared with the NPK plots, respectively. Application of only chemical fertilizer, however, increased MBN concentration, but decreased MBC concentration in soil.展开更多
Wet stability, penetration resistance （PR）, and tensile strength （TS） of paddy soils under a fertilization experiment for 22 years were determined to elucidate the function of soil organic matter in paddy soil sta...Wet stability, penetration resistance （PR）, and tensile strength （TS） of paddy soils under a fertilization experiment for 22 years were determined to elucidate the function of soil organic matter in paddy soil stabilization. The treatments included no fertilization （CK）, normal chemical fertilization （NPK）, double the NPK application rates （2NPK）, and NPK mixed with organic manure （NPK＋OM）. Compared with CK, Fertilization increased soil organic carbon （SOC） and soil porosity. The results of soil aggregate fragmentation degree （SAFD） showed that fast wetting by water was the key fragmentation mechanism. Among the treatments, the NPK＋OM treatment had the largest size of water-stable aggregates and greatest normal mean weight diameter （NMWD） （P ≤ 0.05）, but the lowest PR and TS in both cultivated horizon （Ap） and plow pan. The CK and 2NPK treatments were measured with PR 〉 2.0 MPa and friability index 〈 0.20, respectively, in the Ap horizon, suggesting that the soils was mechanically unfavourable to root growth and tillage. In the plow pan, the fertilization treatments had greater TS and PR than in CK. TS and PR of the tested soil aggregates were negatively correlated to SOC content and soil porosity. This study suggested that chemical fertilization could cause deterioration of mechanical properties while application of organic manure could improve soil stability and mechanical properties.展开更多
Soil acidification is an important process in land degradation around the world as well as in China.Acidification of Alfisols was investigated in the tea gardens with various years of tea cultivation in the eastern Ch...Soil acidification is an important process in land degradation around the world as well as in China.Acidification of Alfisols was investigated in the tea gardens with various years of tea cultivation in the eastern China.Cultivation of tea plants caused soil acidification and soil acidity increased with the increase of tea cultivation period.Soil pH of composite samples from cultivated layers decreased by 1.37,1.62 and 1.85,respectively,after 13,34 and 54 years of tea plantation,as compared to the surface soil obtained from the unused land.Soil acidification rates at early stages of tea cultivation were found to be higher than those at the later stages.The acidification rate for the period of 0-13 years was as high as 4.40 kmol H + ha ?1 year ?1 for the cultivated layer samples.Soil acidification induced the decrease of soil exchangeable base cations and base cation saturation and thus increased the soil exchangeable acidity.Soil acidification also caused the decrease of soil cation exchange capacity,especially for the 54-year-old tea garden.Soil acidification induced by tea plantation also led to the increase of soil exchangeable Al and soluble Al,which was responsible for the Al toxicity to plants.展开更多
基金funded by the Science and Technology Plan for the Belt and Road Innovation Cooperation Project of Jiangsu Province,China(No.BZ2023003)the National Key Research and Development Program of China(No.2021YFD1500202)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA28010100)the“14th Five-Year Plan”Self-Deployment Project of the Institute of Soil Science,Chinese Academy of Sciences(No.ISSAS2418)the National Natural Science Foundation of China(No.42107334)。
文摘Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.
文摘Due to continuous decreases in arable land area and continuous population increases,Chinese soil scientists face great challenges in meeting food demands,mitigating adverse environmental impacts,and sustaining or enhancing soil productivity under intensive agriculture.With the aim of promoting the application of soil science knowledge,this paper reviews the achievements of Chinese scientists in soil resource use and management,soil fertility,global change mitigation and soil biology over the last 30 years.During this period,soil resource science has provided essential support for the use and exploitation of Chinese soil resources,and has itself developed through introduction of new theories such as Soil Taxonomy and new technologies such as remote sensing.Soil fertility science has contributed to the alleviation and elimination of impeding physical and chemical factors that constrain availability of essential nutrients and water in soils,the understanding of nutrient cycling in agroecosystems,and the increase in nutrient use efficiency for sustainable crop production.Chinese soil scientists have contributed to the understanding of the cropland's role in global change,particularly to the understanding of methane and nitrous oxide emission from rice fields and the effect of elevated carbon dioxide and ozone on rice-wheat system.Soil biology research has progressed in biological N fixation,distribution of fauna in Chinese soils,and bioremediation of polluted soils.A new generation of soil scientists has arisen in the last three decades.The gaps between research and application in these soil science fields are also discussed.
基金funded by the National Natural Science Foundation of China(Nos.42020104004 and 42130718).
文摘Soils are a valuable resource with life activity in terrestrial ecosystem,and soil health and its sustainable management are becoming a major focus of global concern.A healthy soil is a“harmonious social system”,which should have good structure,functional state,and buffering performance to maintain the dynamic balance of soil ecosystem.Soil health has become the frontier of soil science.The development of theoretical and practical approaches for soil health evaluation and management is urgently needed.Therefore,further research is needed to develop new techniques and methods for soil health research,construct soil health index and evaluation system,clarify the mechanism and spatial-temporal pattern of soil health conservation,and establish soil health protection and cultivation technology,which would provide scientific and technological support for soil resource protection and sustainable utilization.
基金financially supported by the National Natural Science Foundation of China(Nos.42177239 and 41991330)the“14th Five Year Plan”of Independent Deployment Project of Nanjing Institute of Soil Research,Chinese Academy of Sciences(No.ISSASIP2213)。
文摘New pollutants have become a significant concern in China's efforts toward ecological and environmental protection.Trichloromethane(TCM,CHCl_3),one of these new pollutants,is primarily released into soil and groundwater through various industrial activities.Over the past four decades,researchers have consistently focused on the remediation of TCM-contaminated soil and groundwater using microorganisms and iron-based materials,which hold significant potential for practical application.Understanding the remediation process and the factors influencing TCM degradation through these two methods is crucial for advancing both theoretical research and practical implementation.This review focuses on the degradation mechanisms of TCM in soil and groundwater by microorganisms and iron-based materials.It summarizes the active microorganisms and modified iron-based materials with high TCM degradation capabilities,discusses enhancement measures for both methods in the remediation process,and finally,outlines the challenges faced by these methods.The goal is to provide theoretical references for efficient remediation of TCM-contaminated soil and groundwater.
基金supported by the Zhejiang Provincial Natural Science Foundation,China(Grant No.LQ24C010007)Zhejiang Science and Technology Major Program on Rice New Variety Breeding,China(Grant No.2021C02063)+4 种基金the Agricultural Sciences and Technologies Innovation Program,China(Grant No.CAAS-CSCB-202301)the Key Projects of Zhejiang Provincial Natural Science Foundation,China(Grant No.LZ23C130002)the Youth Innovation Program of Chinese Academy of Agricultural Sciences(Grant No.Y2023QC22)the Joint Open Competitive Project of the Yazhou Bay Seed Laboratory and China National Seed Company Limited(Grant Nos.B23YQ1514 and B23CQ15EP)the External Cooperation Projects of Biotechnology Research Institute,Fujian Academy of Agricultural Sciences,China(Grant No.DWHZ2024-07).
文摘Rice seedling blight,caused by various fungi,including Fusarium oxysporum,poses a severe threat to rice production.As awareness grows regarding the environmental and safety hazards associated with the application of fungicides for managing rice seedling blight,there has been a shift in focus towards biological control agents.In this study,we isolated biocontrol bacteria from paddy fields that significantly inhibited the growth of F.oxysporum in vitro and identified the strains as Bacillus amyloliquefaciens T40 and Bacillus pumilus T208.Additionally,our findings indicated that the combined application of these Bacillus strains in soil was more effective in reducing the incidence of rice seedling blight than their individual use.Analysis of 16S and internal transcribed spacer rRNA gene sequencing data revealed that the mixture of the T40 and T208 strains exhibited the lowest average clustering coefficients,which were negatively correlated with the biomass of F.oxysporum-inoculated rice seedlings.Furthermore,this mixture led to higher stochastic assembly(average|βNTI|<2)and reduced selection pressures on rice rhizosphere bacteria compared with individual strain applications.The mixture of the T40 and T208 strains also significantly increased the expression of defense-related genes.In conclusion,the mixture of the T40 and T208 strains effectively modulates microbial community structures,enhances microbial network stability,and boosts the resistance against rice seedling blight.Our study supports the development and utilization of biological resources for crop protection.
基金supported by the National Key R&D Program of China(No.2020YFC1806801).
文摘Soil bioaccessible and labile As were extracted using in vitro,diffusive gradients in thin films(DGT)and chemical extraction methods.The results showed that As(Ⅲ)was readily converted to As(Ⅴ)in the soils,which was promoted by alkaline conditions and higher content of easily reducible Mn.As(Ⅴ)was not readily reduced to As(Ⅲ)in these soils.The effect of soil pH on bioaccessible As content by in vitro method and labile As content by DGT methodwere inconsistent among different soils due to the coincidence of As(Ⅲ)and As(Ⅴ),with As(Ⅲ)being more readily mobilized in acidic environment while the opposite was true for As(Ⅴ).The labile As extracted by phosphate was significantly correlated with that extracted by in vitro method,while the labile As extracted by the DGT was correlated with that extracted by the CaCl_(2) method.The labile As extracted by the DGT was much lower than that by the in vitro and phosphate methods.The in vitro and phosphate methods extracted As in soils which is tightly bound to Fe oxides through dissolution,complexation and ion exchange.In contrast,the DGT method relied on the adsorption of soil labile As onto ZrO-based binding layer.The higher contents of soil Fe oxides and greater adsorption capacity for As led to the lower content of As measured by the DGT method.In conclusion,the in vitro and phosphate extraction are potential to be used to predict soil bioaccessible As.The DGT method is more suitable for ecological risk prediction.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA24040203)the Inner Mongolia Key R&D Program,China(No.NMKJXM202107)+1 种基金the Key R&D Program of Gansu Province of China(No.21CX6QA026)the Natural Science Foundation of Gansu Province of China(No.20JR5RA074)。
文摘Winter irrigation is a crucial measure for preventing farmland salinity in arid inland regions.However,given the relatively complex process of salt leaching under the influence of freezing and thawing,present salinity management has led to soil quality deterioration in the irrigation areas in Northwest China.To better understand this process,a field experiment was conducted in Huangyang Town,Wuwei City,Gansu Province,China to simulate the evolution of soil profile salinity and alkalinity in a typical oasis farmland under 3-year regular barley planting,using a local prevailing water-salt management mode of drip irrigation for the growing period and winter irrigation for the fallow period.This study investigated the impact of freezing on salt leaching by comparing the soil profile water,heat,and salt movements under different winter irrigation quotas.Compared to no winter irrigation,a reduction in the winter irrigation quota from the standard one to a halved one led to a transition from a sink of 11.05% by salt leaching to a source of 13.75% by salt addition.This means that overwintering soil freezing,especially in oases with deep groundwater tables,can worsen root zone salinization caused by a deficit winter irrigation,through freezing-induced root zone soil water and salt return.Furthermore,dry saline soil dominated by sulfate is at the risk of soil alkalization when freezing-induced oversaturation of solute concentration leads to significant salt precipitation.These findings are crucial for understanding the mechanisms behind the increasing secondary salinization caused by unsustainable winter irrigation in oasis irrigation areas.
基金supported by the Federal Ministry of Food and Agriculture (BMEL)the Federal Ministry for the Environment,Nature Conservation,Nuclear Safety and Consumer Protection (BMUV) through the Fachagentur Nachwachsende Rohstoffe e. V.(FNR)(grant no. 2218 WK53X4)
文摘Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental understanding of the underlying mechanisms that control fine root plasticity.The objective of this study was to determine the influence of soil moisture changes on fine root dynamics and morphology of European beech(Fagus sylvatica L.).We conducted a 30-month study of fine root traits,i.e.,fine root biomass(FRB),productivity,mortality,turnover,specific root length(SRL),specific root area(SRA),and root tip frequency(RTF),along a soil moisture gradient from dry,intermediate,and wet conditions in a near-natural mature beech forest.Sequential root coring with accompanying soil measurements was carried out at three study sites reflecting the gradient in soil water availability.For most fine root traits,we found significant differences between the upper 10 cm and lower soil depths.FRB showed significant differences between study sites,with the lowest FRB at the dry site.However,productivity,turnover,SRL,SRA,and RTF showed no significant differences between sites,but a high variability between seasons,suggesting an adaptation to short-term fluctuations but not to long-term gradients in soil water content(SWC).Linear mixed models revealed that decreasing SWC led to a significant increase in SRL,SRA,and RTF(standardized coefficients:-1.0±0.46,-1.1±0.46,and-1.1±0.43,respectively).Our observations indicate an adaptation strategy of beech to low availability of soil water and drought by forming thin absorptive roots and by maintaining a high seasonal plasticity to tolerate fluctuations in soil moisture.By highlighting the belowground morphological adaptations of mature forests to low soil water availability,our results provide novel insights into the structure and dynamics of forest ecosystem adaptations to climate change.
基金funded by the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA28020202)the National Natural Science Foundation of China (No. 42277336)+3 种基金the Natural Science Foundation of Jiangsu Province, China (No. BK20221561)the China Agriculture Research System (Nos. CARS-03 and CARS52)the National Key Research and Development Program of China (No. 2022YFD1500401)the Jiangsu Agricultural Science and Technology Innovation Fund of China (No. CX(24)1003)。
文摘Diazotrophs make important contributions to nitrogen(N) inputs in agricultural ecosystems. However, strong evidence of the effects of conservation tillage(CT) on the coexistence and assembly of soil diazotrophic community and related mechanisms is lacking. Here, a long-term experiment was conducted to study the impacts of CT on the coexistence and assembly patterns of soil diazotrophic community in Lishu County, Jilin Province, North China. Compared to traditional tillage(control, CK), CT significantly reduced both the N fixation rate in top 0–10 cm soil and the alpha diversity of diazotrophic community while increasing the density of diazotrophic and overall bacterial communities. Conservation tillage also reduced the competitive relationships within the diazotrophic community and enhanced network stability. Furthermore, diazotroph assembly was dominated by deterministic processes(relative influence =68.63%) under CK and stochastic processes(relative influence = 58.82%) under CT. Soil depth and total N(TN) were identified as crucial predictors shaping the assembly processes of diazotrophic community under different tillage practices. The relative influence of stochastic processes on diazotrophic community under CT varied more significantly with increasing soil depth. Overall, tillage practice and soil depth had significant influences on the coexistence and assembly processes of soil diazotrophic community. Moreover, long-term CT may impact the selection of N fixation agents and the specific taxa associated with N fixers. Our results indicated that in CT systems, relatively sufficient nutrient availability led to a reduction in interspecies competition, an increase in network stability, and a greater influence of stochastic processes on community assembly. These findings may help us better understand biological N fixation in sustainable agricultural systems.
基金supported by the National Natural Science Foundation of China(Nos.42207371 and 32071642)the Scientific Project of Jiangsu Vocational College of Agriculture and Forestry,China(No.2021kj17)the Key Research Projects of Jiangsu Vocational College of Agriculture and Forestry,China(No.2023kj14)。
文摘Green prevention and control management of soil-borne fungal diseases is a hot topic in agriculture,ecology,and the environment.It is an important way to effectively prevent and control soil-borne fungal diseases,solve soil degradation caused by continuous cropping obstacles,and fulfill the sustainable development of agriculture through revealing the mechanisms of functional substances to develop highly effective soil amendments.Humic acid shows an inhibitory effect on soil-borne pathogenic fungi,such as Fusarium oxysporum,Choanephora cucurbitarum,and Rhizoctonia solani,with the inhibition rate exceeding 80%.The molecular and elemental composition and contents of–COOH,phenolic C,methoxy group C,carboxyl C,aromatic C–O,anomeric C,and other functional groups of humic acid have been inferred to be responsible for its inhibitory effects on pathogenic fungi in previous research.The inhibitory mechanisms mainly include cell physiological morphology,biochemical process reactions,and molecular signal transduction.This review systematically summarizes the chemical structure,fungistatic effects,variable characteristics,and inhibitory mechanisms of humic acid,aiming to provide a theoretical basis for the development of green and efficient prevention and control technologies for soil-borne fungal diseases.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDA28110100 and XDA28020202)the National Key Research and Development Program of China(No.2022YFD1500203)+3 种基金the National Natural Science Foundation of China(No.42177332)the China Agriculture Research System(Nos.CARS-03 and CARS-52)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2023325)the Anhui Provincial Key Research and Development Project,China(No.2023n06020056).
文摘Straw return is the main practice used to increase soil organic matter(SOM)in agricultural ecosystems.To increase the efficiency of straw conversion to SOM,a large number of microbial inoculants have been developed.However,their effects are poor because of the complex water and temperature conditions,especially under sodic conditions.Small molecules can rapidly shift soil microbial communities and improve their ability to transform exogenous organic matter into SOM,providing a new direction for promoting high-efficiency straw conversion into SOM.In this study,we conducted a^(13)C-labeled straw degradation experiment using small molecules derived from lignin(LSMs)and humus(HSMs)as activators,investigating their effects on the microbial communities and formation of newly formed mineral-associated(^(13)C-MAOM)and particulate(^(13)C-POM)organic matter from^(13)C-labeled straw in both sodic and non-sodic soils.The^(13)C-labeled straw was mainly converted into^(13)C-MAOM,accounting for 73.97%–92.67%of the newly formed SOM.Biopolymer-derived small molecules decreased the exchangeable sodium percentage(ESP),but increased contents of^(13)C-MAOM and^(13)C-POM by shifting microbial communities,strengthening microbial cross-trophic interactions,enhancing enzyme activities,and increasing microbial residues in both soils.Addition of HSMs had greater impacts on^(13)C-MAOM formation than LSM addition.The^(13)C-MAOM and^(13)C-POM formation negatively correlated with ESP,but positively correlated with microbial cross-trophic interactions and enzyme activities in both soils.Our results suggest that biopolymer-derived small molecules promote^(13)C-MAOM and^(13)C-POM formation associated with microbial cross-trophic interactions between protistan predators and primary decomposers.Our study provides scientific support for future attempts to stimulate microbial cross-trophic interactions for boosting SOM accumulation under stressed conditions.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program of China(No.2019QZKK0306-02)the National Natural Science Foundation of China(Nos.42322102 and 42271058)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2021310)the Science&Technology Fundamental Resources Investigation Program of China(No.2022FY100202)
文摘Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of soil C:N:P ratios are still poorly understood on the Qinghai-Tibetan Plateau of China.In this study,we therefore combined data of the geography,climate,soil properties,and vegetation characteristics from 319 sites across the plateau to investigate their relationships with the horizontal and vertical patterns of SOC,TN,and TP concentrations and their stoichiometric ratios(C:N and N:P).We observed higher SOC(30.5–46.8 mg g^(-1)),TN(2.4–3.4 mg g^(-1)),C:N(14.7–18.0),and N:P(6.9–8.0)in alpine meadows,forests,and shrublands and higher TP(1.6 mg g^(-1))in croplands.Overall,SOC,TN,TP,C:N,and N:P showed decreasing trends(by 67%,64%,19%,12%,and 54%,respectively)along the whole soil profile(0–100 cm).Soil cation exchange capacity and bulk density were the stronger environmental drivers of SOC and TN.Soil TP showed latitudinal and longitudinal increasing trends in all soil layers.Soil properties explained most of the variations in SOC(67%–90%),TN(67%–87%),C:N(61%–89%),and N:P(64%–85%),with increasing impacts along the soil profile.Geography and climate influenced soil TP directly and indirectly through their impacts on soil properties,with geography being the predominant driver(46%–65%)along the soil profile.The variation in soil C:N was mostly driven by SOC and TN,and the direct and indirect effects of the environmental factors were relatively weak.Geography,climate,soil properties,and vegetation characteristics indirectly impacted soil N:P through their impacts on TN and TP in all the soil layers.Altogether,our findings illuminate the relative contributions of geography,climate,soil properties,and vegetation characteristics to soil C:N and N:P,thus enhancing our understanding of C,N,and P cycling across the Qinghai-Tibetan Plateau.
基金financially supported by the Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2021309)the Capacity-building Projects by the Beijing Academy of Agriculture and Forestry Sciences,China(No.KJCX20220414)the National Natural Science Foundation of China(No.42277303)。
文摘Dear Editor,Plastics have been ubiquitous in the environment due to their high amounts of production and application(Geyer et al.,2017).In 2021,annual global plastic production increased to 39.07 billion tons(Rede et al.,2023).Plastics undergo weathering,photolysis,and other environmental effects and form emerging contaminants with small particle sizes that can easily migrate,i.e.,microplastics(MPs,<5 mm)(Auta et al.,2017).
基金supported by the National Key Research and Development Program of China(Grant No.2024YFD1501102)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20220163)+2 种基金the Jiangxi Province Natural Science Foundation(Grant No.20224BAB203031)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA0440202)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2023327)。
文摘Soil erosion is the primary factor causing the loss of soil resources and land degradation.Clarifying the current status of soil erosion in China and the characteristics of future changes under different pathways of development is important to the global management of soil resources,food security,and ecosystem services.We used the revised universal soil loss equation and the most recent and reliable soil and environmental data to characterize soil erosion in China at present and under typical Shared Socioeconomic Pathways and Representative Concentration Pathways(i.e.,SSP1–2.6 and SSP5–8.5)in the medium-and long-term future(2050 and 2100).The current average rate of soil erosion in China was 14.78 t ha^(-1)yr^(-1),with a total amount of about 14.0 Pg yr^(-1).The amount of total erosion increased by 5.0%,10.8%,9.9%,and 25.9%for scenarios 2050_SSP1–2.6,2050_SSP5–8.5,2100_SSP1–2.6,and 2100_SSP5–8.5,respectively,compared to the baseline amount in 2010.The contribution of climate change and land use to the increase in erosion ranged from 9.5%to 31.5%and-6.95%to-1.78%,respectively,with the contribution of climate change about 2.36-to 7.54-fold larger than the contribution of land use.Converting arable barren land into forest and grassland or adopting conservation tillage practices for farmland,could nevertheless effectively offset the increase in erosion under the four future scenarios.This study provides data and a scientific basis for managing soil erosion in China and provides a useful reference for conserving global land resources and formulating policies to cope with climatic and environmental changes.
基金supported by the National Key Research and Development Program of China(2022YFB3903302).
文摘Accurately mapping the spatial distribution of soil organic carbon(SOC)is crucial for guiding agricultural management and improving soil carbon sequestration,especially in fragmented agricultural landscapes.Although remote sensing provides spatially continuous environmental information about heterogeneous agricultural landscapes,its relationship with SOC remains unclear.In this study,we hypothesized that multi-category remote sensing-derived variables can enhance our understanding of SOC variation within complex landscape conditions.Taking the Qilu Lake watershed in Yunnan,China,as a case study area and based on 216 topsoil samples collected from irrigation areas,we applied the extreme gradient boosting(XGBoost)model to investigate the contributions of vegetation indices(VI),brightness indices(BI),moisture indices(MI),and spectral transformations(ST,principal component analysis and tasseled cap transformation)to SOC mapping.The results showed that ST contributed the most to SOC prediction accuracy,followed by MI,VI,and BI,with improvements in R2 of 29.27,26.83,19.51,and 14.43%,respectively.The dominance of ST can be attributed to the fact that it contains richer remote sensing spectral information.The optimal SOC prediction model integrated soil properties,topographic factors,location factors,and landscape metrics,as well as remote sensing-derived variables,and achieved RMSE and MAE of 15.05 and 11.42 g kg-1,and R2 and CCC of 0.57 and 0.72,respectively.The Shapley additive explanations deciphered the nonlinear and threshold effects that exist between soil moisture,vegetation status,soil brightness and SOC.Compared with traditional linear regression models,interpretable machine learning has advantages in prediction accuracy and revealing the influences of variables that reflect landscape characteristics on SOC.Overall,this study not only reveals how remote sensing-derived variables contribute to our understanding of SOC distribution in fragmented agricultural landscapes but also clarifies their efficacy.Through interpretable machine learning,we can further elucidate the causes of SOC variation,which is important for sustainable soil management and agricultural practices.
文摘Heavy metals in variable charge soil are highly bioavailable and easy to transfer into plants. Since it is impossible to completely eliminate rice planting on contaminated soils, some remediation and mitigation techniques are necessary to reduce metal bioavailability and uptake by rice. This pot experiment investigated the effects of seven amendments on the growth of rice and uptake of heavy metals from a paddy soil that was contaminated by copper and cadmium. The best results were from the application of limestone that increased grain yield by 12.5-16.5 fold, and decreased Cu and Cd concentrations in grain by 23.0%--50.4%. Application of calcium magnesium phosphate, calcium silicate, pig manure, and peat also increased the grain yield by 0.3-15.3 fold, and effectively decreased the Cu and Cd concentrations in grain. Cd concentration in grain was slightly reduced in the treatments of Chinese milk vetch and zinc sulfate. Concentrations of Cu and Cd in grain and straw were dependent on the available Cu and Cd in the soils, and soil available Cu and Cd were significantly affected by the soil pH.
基金Supported by the National Key Technology R&D Program of China (No.2009BADC6B02)the National Natural Science Foundation of China (No.40971135)
文摘The liming potential of some crop residues and their biochars on an acid Ultisol was investigated using incubation experiments. Rice hulls showed greater liming potential than rice hull biochar, while soybean and pea straws had less liming potential than their biochars. Due to their higher alkalinity, biochars from legume materials increased soil pH much compared to biochars from non-legume materials. The alkalinity of biochars was a key factor affecting their liming potential, and the greater alkalinity of biochars led to greater reductions in soil acidity. The incorporation of biochars decreased soil exchangeable acidity and increased soil exchangeable base cations and base saturation, thus improving soil fertility.
基金Project supported by the National Key Basic Research Support Foundation of China (No.2002CB410810).
文摘A long-term experiment was conducted to investigate how long-term fertilization and rice straw incorporation into soil affect soil glomalin, C and N. The combined application of chemical fertilizer and straw resulted in a significant increase in both soil easily extractable glomalin (EEG) and total glomalin (TG) concentrations, as compared with application of only chemical fertilizer or no fertilizer application. The EEG and TG concentrations of the NPKS (nitrogen, phosphorus, and potassium fertilizer application + rice straw return) plot were 4.68% and 5.67% higher than those of the CK (unfertilized control) plot, and 9.87% and 6.23% higher than those of the NPK (nitrogen, phosphorus, and potassium fertilizer applied annually) plot, respectively. Application of only chemical fertilizer did not cause a statistically significant change of soil glomalin compared with no fertilizer application. The changes of soil organic C (SOC) and total N (TN) contents demonstrated a similar trend to soil glomalin in these plots. The SOC and TN contents of NPKS plot were 15.01% and 9.18% higher than those of the CK plot, and 8.85% and 14.76% higher than those of the NPK plot, respectively. Rice straw return also enhanced the contents of microbial biomass C (MBC) and microbial biomass N (MBN) in the NPKS plot by 7.76% for MBC and 31.42% for MBN compared with the CK plot, and 12.66% for MBC and 15.07% for MBN compared with the NPK plots, respectively. Application of only chemical fertilizer, however, increased MBN concentration, but decreased MBC concentration in soil.
基金Project supported by the National Natural Science Foundation of China (No.40371059).
文摘Wet stability, penetration resistance （PR）, and tensile strength （TS） of paddy soils under a fertilization experiment for 22 years were determined to elucidate the function of soil organic matter in paddy soil stabilization. The treatments included no fertilization （CK）, normal chemical fertilization （NPK）, double the NPK application rates （2NPK）, and NPK mixed with organic manure （NPK＋OM）. Compared with CK, Fertilization increased soil organic carbon （SOC） and soil porosity. The results of soil aggregate fragmentation degree （SAFD） showed that fast wetting by water was the key fragmentation mechanism. Among the treatments, the NPK＋OM treatment had the largest size of water-stable aggregates and greatest normal mean weight diameter （NMWD） （P ≤ 0.05）, but the lowest PR and TS in both cultivated horizon （Ap） and plow pan. The CK and 2NPK treatments were measured with PR 〉 2.0 MPa and friability index 〈 0.20, respectively, in the Ap horizon, suggesting that the soils was mechanically unfavourable to root growth and tillage. In the plow pan, the fertilization treatments had greater TS and PR than in CK. TS and PR of the tested soil aggregates were negatively correlated to SOC content and soil porosity. This study suggested that chemical fertilization could cause deterioration of mechanical properties while application of organic manure could improve soil stability and mechanical properties.
基金Supported by the National Nature Science Foundation of China (No. 30872009)the Earmarked Fund for Modern Agro-Industry Technology Research System of China (No. nycytx-23)
文摘Soil acidification is an important process in land degradation around the world as well as in China.Acidification of Alfisols was investigated in the tea gardens with various years of tea cultivation in the eastern China.Cultivation of tea plants caused soil acidification and soil acidity increased with the increase of tea cultivation period.Soil pH of composite samples from cultivated layers decreased by 1.37,1.62 and 1.85,respectively,after 13,34 and 54 years of tea plantation,as compared to the surface soil obtained from the unused land.Soil acidification rates at early stages of tea cultivation were found to be higher than those at the later stages.The acidification rate for the period of 0-13 years was as high as 4.40 kmol H + ha ?1 year ?1 for the cultivated layer samples.Soil acidification induced the decrease of soil exchangeable base cations and base cation saturation and thus increased the soil exchangeable acidity.Soil acidification also caused the decrease of soil cation exchange capacity,especially for the 54-year-old tea garden.Soil acidification induced by tea plantation also led to the increase of soil exchangeable Al and soluble Al,which was responsible for the Al toxicity to plants.
