期刊文献+
共找到159,438篇文章
< 1 2 250 >
每页显示 20 50 100
Soil microbial attributes along a chronosequence of Scots pine(Pinus sylvestris var. mongolica) plantations in northern China 认领
1
作者 Xiaodong YAO Wenjing ZENG +1 位作者 Hui ZENG Wei WANG 《土壤圈:英文版》 SCIE CAS CSCD 2020年第4期433-442,共10页
Soil microorganisms play a key role in soil organic matter dynamics, nutrient cycling, and soil fertility maintenance in forest ecosystems, and they are influenced by stand age and soil depth. However, few studies hav... Soil microorganisms play a key role in soil organic matter dynamics, nutrient cycling, and soil fertility maintenance in forest ecosystems, and they are influenced by stand age and soil depth. However, few studies have simultaneously considered these two factors. In this study, we measured soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), soil basal respiration (SBR) rate, and potential extracellular enzyme activity (EEA) in soil to a depth of 60 cm under 10-, 30-, and 40-year-old Scots pine (Pinus sylvestris var. mongolica) stands (Y10, Y30, and Y40, respectively) in plantations in northern China in 2011. Soil water content (SWC), soil pH, soil organic carbon (SOC), and soil total nitrogen (STN) were also measured to explore their effects on soil microbial indices across different stand ages and soil depths. Our results showed that SMBC, SMBN, and the SBR rate were generally higher for the Y30 stand than for the Y10 and Y40 stands. Potential EEA, except forα-glucosidase, decreased significantly with increasing stand age. Soil organic carbon,STN, SWC, and soil pH explained 67%of the variation in soil microbial attributes among the three stand ages. For the same stand age, soil microbial biomass and the SBR rate decreased with soil depth. Lower microbial biomass, lower SBR rate, and lower EEA for the mature Y40 stand indicate lower substrate availability for soil microorganisms, lower soil quality, and lower microbial adaptability to the environment. Our results suggest that changes in soil quality with stand age should be considered when determining the optimum rotation length of plantations and the best management practices for afforestation programs. 展开更多
关键词 soil microbial metabolism quotient(gCO2) soil basal respiration soil depth soil microbial biomass soil organic matter dynamics soil potential extracellular enzyme activity stand age
Combined application of a straw layer and flue gas desulphurization gypsum to reduce soil salinity and alkalinity 认领
2
作者 Yonggan ZHAO Yan LI +2 位作者 Shujuan WANG Jing WANG Lizhen XU 《土壤圈:英文版》 SCIE CAS CSCD 2020年第2期226-235,共10页
Burying a straw layer and applying flue gas desulphurization(FGD)gypsum are effective practices to ameliorate soil salinization or alkalization and to increase crop yield;however,little information exists on the effec... Burying a straw layer and applying flue gas desulphurization(FGD)gypsum are effective practices to ameliorate soil salinization or alkalization and to increase crop yield;however,little information exists on the effects of such integration in saline-alkali soils.A soil column experiment was conducted to investigate the effects of a straw layer plus FGD gypsum on soil salinity and alkalinity.We placed a straw layer(5 cm thick)at a depth of 30 cm and mixed FGD gypsum into the 0–20 cm soil layer at application rates of 7.5,15.0,22.5,and 30.0 t ha^-1,with no straw layer and FGD gypsum as a control(CK).The soil water content in the 0–30 cm soil layer was significantly higher(>7.8%)in the treated soil profiles after infiltration than in the CK,but decreased after evaporation.The electrical conductivity(EC)of the 10–30 cm soil layer was 230.2%and 104.9%higher in the treated soil profiles than in the CK after infiltration and evaporation,respectively,and increased with increasing rates of FGD gypsum application,with Ca^2+and SO4^2-being the main dissolved salts.Compared to those in the CK,the concentrations of Na^+,Cl^-,and HCO3-decreased in the treated soil profiles at depths above 55 cm,but the other soluble ions increased,after infiltration.A similar trend occurred after evaporation for all soluble ions except for HCO3-.The p H and exchangeable sodium percentage in the treated soil profiles were significantly lower than those in the CK over the entire profile,and decreased with increasing FGD gypsum application rates.Therefore,the incorporation of a straw layer plus FGD gypsum can reduce salinity and alkalinity,but the quantity of FGD gypsum should be controlled in saline-alkali soils. 展开更多
关键词 alkaline SOIL SALINE-ALKALI stress saline SOIL salt accumulation secondary SALINIZATION SOIL AMELIORATION SOIL reclamation
微生物改良基质对新围垦海涂盐土改良的初步研究 认领
3
作者 尚辉 颜安 +5 位作者 韩瑞 姚宇阗 常义军 杨花蕾 陈立华 孟天竹 《农业工程学报》 EI CAS CSCD 北大核心 2020年第8期120-126,共7页
海涂围垦区是陆海过渡带,围垦区土壤的传统洗盐和培肥技术易威胁近海生态环境,因此,探索新型、生态的盐土改良技术十分重要。该研究初步研究了新型微生物改良基质的盐土改良功能,结果表明微生物改良基质效果显著。相较于对照处理,微生... 海涂围垦区是陆海过渡带,围垦区土壤的传统洗盐和培肥技术易威胁近海生态环境,因此,探索新型、生态的盐土改良技术十分重要。该研究初步研究了新型微生物改良基质的盐土改良功能,结果表明微生物改良基质效果显著。相较于对照处理,微生物改良基质处理水稻产量增加了83.2%(P<0.05);土壤饱和含水率、田间持水量、总孔隙度、有机质、全氮、速效钾分别增加了13.80%、20.00%、6.80%、2.30倍、53.00%、31.00%(P<0.05);土壤容重降低了6.90%;土壤细菌、真菌和放线菌数量分别增加了10.30、11.20和3.18倍;水稻生育期累积灌溉水量减少了35.20%;0~10和>10~20cm土层可溶性盐质量分数分别降低了61.10%和54.40%。微生物改良基质能够在短期内加速盐分洗脱,提升土壤质量,是海涂新围垦区盐土改良的生态高效措施。 展开更多
关键词 土壤 盐分 水分 海涂新围垦区 微生物改良基质 土壤改良
在线阅读 下载PDF
Variation in glomalin in soil profiles and its association with climatic conditions,shelterbelt characteristics,and soil properties in poplar shelterbelts of Northeast China 认领
4
作者 Qiong Wang Wenjie Wang +2 位作者 Zhaoliang Zhong Huimei Wang Yujie Fu 《林业研究:英文版》 SCIE CAS CSCD 2020年第1期279-290,共12页
Glomalin-related soil protein(GRSP)sequesters large amounts of carbon and plays important roles in maintaining terrestrial soil ecosystem functions and ecological restoration;however,little is known about GRSP variati... Glomalin-related soil protein(GRSP)sequesters large amounts of carbon and plays important roles in maintaining terrestrial soil ecosystem functions and ecological restoration;however,little is known about GRSP variation in 1-m soil profiles and its association with stand characteristics,soil properties,and climatic conditions,hindering GRSP-related degraded soil improvement and GRSP evaluation.In this study,we sampled soils from 1-m profiles from poplar(Populus spp.)shelterbelts in Northeast China.GRSP contents were 1.8–2.0 times higher in the upper 40 cm soil layers than at 40–100 cm.GRSP-related soil organic carbon(SOC)sequestration in deeper soil layers was*1.2 times higher than in surface layers.The amounts of GRSP-related nutrients were similar throughout the soil profile.A redundancy analysis showed that in both surface and deeper layers,soil properties(pH,electrical conductivity,water,SOC,and soil nutrients)explained the majority of the GRSP variation(59.5–84.2%);the second-most-important factor in GRSP regulation was climatic conditions(temperature,precipitation,and altitude),while specific shelterbelt characteristics had negligible effects(<5%).Soil depth and climate indirectly affected GRSP features via soil properties,as manifested by structural equation model analysis.Our findings demonstrate that GRSP is important for carbon storage in deep soils,regardless of shelterbelt characteristics.Future glomalin assessments should consider these vertical patterns and possible regulating mechanisms that are related to soil properties and climatic changes. 展开更多
关键词 SOIL depth Glomalin-related SOIL protein(GRSP) SOIL organic carbon storage Climate change SOIL improvement
在线阅读 下载PDF
宜春地区不同地块不同深度的典型土体定名与工程分类研究 认领
5
作者 陆有忠 张正奇 徐陈明 《宜春学院学报》 2020年第3期50-54,共5页
对宜春地区不同地块不同深度的几种典型原始土样(非扰动)进行了关于土体定名实验研究,并在此基础上对这几种土样进行了精确的工程分类。本次实验选取了宜春不同地块不同深度的原始土样,首先对这几种土样进行密度测量和孔隙率测量的实验... 对宜春地区不同地块不同深度的几种典型原始土样(非扰动)进行了关于土体定名实验研究,并在此基础上对这几种土样进行了精确的工程分类。本次实验选取了宜春不同地块不同深度的原始土样,首先对这几种土样进行密度测量和孔隙率测量的实验。为了获得精确的实验结果,在尽量不扰动土样的基础上,对每一种土样进行平行测定,最终得出它们不同的密度类别与孔隙率,通过查找与对比各类土的密度理论值,根据孔隙比与孔隙率的数学关系,换算出相应的孔隙比,进而对上述原始土样进行定名与工程分类。通过研究,进一步判断出宜春地区典型土体的物理特性和力学性质,进而为该地区正在进行的棚户区改造项目建设所做的地基处理、基坑开挖与支护、边坡防护支护等提供必要而有意义的理论依据,也达到了科研服务地方经济建设的目的。 展开更多
关键词 宜春地区 土的密度 土的定名 土的工程分类
在线阅读 下载PDF
Effects of seasonal variation on soil microbial community structure and enzyme activity in a Masson pine forest in Southwest China 认领
6
作者 LUO Song-ping HE Bing-hui +2 位作者 ZENG Qing-ping LI Nan-jie YANG Lei 《山地科学学报:英文版》 SCIE CSCD 2020年第6期1398-1409,共12页
Soil microbial communities and enzyme activities play key roles in soil ecosystems.Both are sensitive to changes in environmental factors,including seasonal temperature,precipitation variations and soil properties.To ... Soil microbial communities and enzyme activities play key roles in soil ecosystems.Both are sensitive to changes in environmental factors,including seasonal temperature,precipitation variations and soil properties.To understand the interactive mechanisms of seasonal changes that affect soil microbial communities and enzyme activities in a subtropical masson pine(Pinus massoniana)forest,we investigated the soil microbial community structure and enzyme activities to identify the effect of seasonal changes on the soil microbial community for two years in Jinyun Mountain National Nature Reserve,Chongqing,China.The soil microbial community structure was investigated using phospholipid fatty acids(PLFAs).The results indicated that a total of 36 different PLFAs were identified,and 16:0 was found in the highest proportions in the four seasons,moreover,the total PLFAs abundance were highest in spring and lowest in winter.Bacteria and actinomycetes were the dominant types in the study area.Seasonal changes also had a significant(P<0.05)influence on the soil enzyme activity.The maximum and minimum values of the invertase and catalase activities were observed in autumn and winter,respectively.However,the maximum and minimum values of the urease and phosphatase acid enzymatic activities were found in spring and winter,respectively.Canonical correspondence analysis(CCA)analysis revealed that the seasonal shifts in soil community composition and enzyme activities were relatively more sensitive to soil moisture and temperature,but the microbial community structure and enzyme activity were not correlated with soil pH in the study region.This study highlights how the seasonal variations affect the microbial community and function(enzyme activity)to better understand and predict microbial responses to future climate regimes in subtropical area. 展开更多
关键词 PLFA analysis Soil microorganisms soil enzymes Seasonal shifts Soil moisture Soil temperature
Temperature sensitivity of soil organic matter decomposition varies with biochar application and soil type 认领
7
作者 Tatiana FRITTL Luiza CANISARES +3 位作者 Edvaldo SAGRILO Klaus BUTTERBACH-BAHL Michael DANNENMANN Carlos EPCERRI 《土壤圈:英文版》 SCIE CAS CSCD 2020年第3期336-342,共7页
Biochar application has the potential to improve soil fertility and increase soil carbon stock, especially in tropical regions. Information on the temperature sensitivity of carbon dioxide(CO2) evolution from biochar-... Biochar application has the potential to improve soil fertility and increase soil carbon stock, especially in tropical regions. Information on the temperature sensitivity of carbon dioxide(CO2) evolution from biochar-amended soils at very high temperatures, as observed for tropical surface soils, is limited but urgently needed for the development of region-specific biochar management targeted to optimize biochar effects on soil functions. Here, we investigated the temperature sensitivity of soil respiration to the addition of different rates of Miscanthus biochar(0, 6.25, 12.5, and 25 Mg ha-1) in two types of soils with contrasting textures. Biochar-amended soil treatments and their controls were incubated at constant temperatures of 20, 30, and 40℃. Overall, our results show that: i) considering data from all treatments and temperatures, the addition of biochar decreased soil CO2 emissions when compared to untreated soils;ii) CO2 emissions from biochar-amended soils had a higher temperature sensitivity than those from biochar-free soils;iii) the temperature sensitivity of soil respiration in sandy soils was higher than that in clay soils;and iv) for clay soils, relative increases in soil CO2 emissions from biochar-amended soils were higher when the temperature increased from 30 to 40℃, while for sandy soils, the highest temperature responses of soil respiration were observed when increasing the temperature from 20 to 30℃. Together, these findings suggest a significantly reduced potential to increase soil organic carbon stocks when Miscanthus biochar is applied to tropical soils at high surface temperatures, which could be counteracted by the soil-and weather-specific timing of biochar application. 展开更多
关键词 carbon dioxide clay soil greenhouse gas emission Miscanthus biochar sandy soil tropical soil
Factors determining soil water heterogeneity on the Chinese Loess Plateau as based on an empirical mode decomposition method 认领
8
作者 GONG Yidan XING Xuguang WANG Weihua 《干旱区科学:英文版》 SCIE CSCD 2020年第3期462-472,共11页
Soil water is a critical resource,and as such is the focus of considerable physical research.Characterization of the distribution and spatial variability of soil water content(SWC)offers important agronomic and enviro... Soil water is a critical resource,and as such is the focus of considerable physical research.Characterization of the distribution and spatial variability of soil water content(SWC)offers important agronomic and environmental information.Estimation of non-stationary and non-linear SWC distribution at different scales is a research challenge.Based on this context,we performed a case study on the Chinese Loess Plateau,with objectives of investigating spatial variability of SWC and soil properties(i.e.,soil particle composition,organic matter and bulk density),and determining multi-scale correlations between SWC and soil properties.A total of 86 in situ sampling sites were selected and 516 soil samples(0–60 cm depth with an interval of 10 cm)were collected in May and June of 2019 along the Yangling-Wugong-Qianxian transect,with a length of 25.5 km,in a typical wheat-corn rotation region of the Chinese Loess Plateau.Classical statistics and empirical mode decomposition(EMD)method were applied to evaluate characteristics of the overall and scale-specific spatial variation of SWC,and to explore scale-specific correlations between SWC and soil properties.Results showed that the spatial variability of SWC along the Yangling-Wugong-Qianxian transect was medium to weak,with a variability coefficient range of 0.06–0.18,and it was gradually decreased as scale increased.We categorized the overall SWC for each soil layer under an intrinsic mode function(IMF)number based on the scale of occurrence,and found that the component IMF1 exhibited the largest contribution rates of 36.45%–56.70%.Additionally,by using EMD method,we categorized the general variation of SWC under different numbers of IMFs according to occurrence scale,and the results showed that the calculated scales among SWC for each soil layer increased in correspondence with higher IMF numbers.Approximately 78.00%of the total variance of SWC was extracted in IMF1 and IMF2.Generally,soil texture was the dominant control on SWC,and the influence of the three types 展开更多
关键词 bulk density loess plateau soil water soil organic matter soil texture spatial variability
在线阅读 免费下载
土壤环境管理难点及对策研究 认领
9
作者 蔡笠 《绿色科技》 2020年第10期66-67,74,共3页
指出了近年来随着我国经济的快速发展,土壤的环境质量现状却因经济的快速发展而日益变得严重。我国土壤问题十分严峻并且与土壤相关的治理工作也不容乐观。我国土壤环境管理存在着不同区域管理差异明显、法律法规不完善、资金短缺以及... 指出了近年来随着我国经济的快速发展,土壤的环境质量现状却因经济的快速发展而日益变得严重。我国土壤问题十分严峻并且与土壤相关的治理工作也不容乐观。我国土壤环境管理存在着不同区域管理差异明显、法律法规不完善、资金短缺以及企业与公众环保意识薄弱等问题。对此,以我国土壤环境管理的难点和困难着手,为完善我国土壤环境管理问题提出了相应的解决对策,以供参考。 展开更多
关键词 土壤 土壤环境管理 土壤环境质量
在线阅读 下载PDF
Research Progress on the Effect of Biochar on Soil Organic Carbon 认领
10
作者 Shuhong LIU 《农业生物技术:英文版》 CAS 2020年第2期79-81,共3页
Soil organic carbon has been identified as one of the most important components in soil.Changes in soil organic carbon content will significantly affect atmospheric CO2 concentration,which is related to soil fertility... Soil organic carbon has been identified as one of the most important components in soil.Changes in soil organic carbon content will significantly affect atmospheric CO2 concentration,which is related to soil fertility,water holding capacity,nutrient cycling,and changes in microbial communities.In recent years,biochar has been proven to be an effective material for increasing carbon storage,and research on the application of biochar in soil ecosystem carbon sequestration and emission reduction functions has received widespread attention.However,due to differences in the specific methods and research objects used in the research process,the current mechanism of the impact of biochar on soil organic carbon is still controversial.This paper mainly revealed the effects of biochar on soil organic carbon from the aspects of the effects of biochar addition on soil aggregates and microorganisms,and also elaborated on the direction worth exploring and objectively evaluated the impact mechanism of biochar on soil organic carbon. 展开更多
关键词 BIOCHAR SOIL ORGANIC carbon SOIL AGGREGATE SOIL MICROORGANISMS
在线阅读 下载PDF
Method development for estimating soil organic carbon content in an alpine region using soil moisture data 认领
11
作者 Qi LUO Kun YANG +1 位作者 Yingying CHEN Xu ZHOU 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2020年第4期591-601,共11页
The high soil organic carbon(SOC) content in alpine meadow can significantly change soil hydrothermal properties and further affect the soil temperature and moisture as well as the surface water and energy budget. The... The high soil organic carbon(SOC) content in alpine meadow can significantly change soil hydrothermal properties and further affect the soil temperature and moisture as well as the surface water and energy budget. Therefore, this study first introduces a parameterization scheme to describe the effect of SOC content on soil hydraulic and thermal parameters in a land surface model(LSM), and then the SOC content is estimated by minimizing the difference between observed and simulated surface-layer soil moisture. The accuracy of the estimated SOC content was evaluated using in situ observation data at a soil moisture and temperature-measuring network in Naqu, central Tibetan Plateau. Sensitivity experiments show that the optimum time window for stabilizing the estimation results cannot be shorter than three years. In the experimental area, the estimated SOC content can generally reflect the spatial distribution of the measurements, with a root mean square error of 0.099 m~3 m~(-3), a mean bias of 0.043 m~3 m~(-3), and a correlation coefficient of 0.695. The estimated SOC content is not sensitive to the temporal frequency of the soil moisture data input. Even if the temporal frequency is as low as that of current soil moisture products derived from passive microwave satellites, the estimation result is still stable. Therefore, by combining a high-quality satellite soil moisture product and a parameter optimization method, it is possible to obtain grid-scale effective parameter values, such as SOC content,for an LSM and improve the simulation ability of the LSM. 展开更多
关键词 LAND surface model SOIL organic carbon content SOIL POROSITY SOIL PARAMETER estimation
Comparison of Carbon, Nitrogen, and Sulfur in Coastal Wetlands Dominated by Native and Invasive Plants in the Yancheng National Nature Reserve, China 认领
12
作者 WAN Siang LIU Xingtu +1 位作者 MOU Xiaojie ZHAO Yongqiang 《中国地理科学:英文版》 SCIE CSCD 2020年第2期202-216,共15页
The rapid invasion of the plant Spartina alterniflora in coastal wetland areas can threaten the capacity of their soils to store carbon(C),nitrogen(N),and sulfur(S).In this study,we investigated the spatial and tempor... The rapid invasion of the plant Spartina alterniflora in coastal wetland areas can threaten the capacity of their soils to store carbon(C),nitrogen(N),and sulfur(S).In this study,we investigated the spatial and temporal distribution patterns of C,N and S of both soil and(native and invasive)plants in four typical coastal wetlands in the core area of the Yancheng National Nature Reserve,China.The results show that the invasive S.alterniflora greatly influenced soil properties and increased soil C,N and S storage capacity:the stock(mean±standard error)of soil organic carbon(SOC,(3.56±0.36)kg/m~3),total nitrogen(TN,(0.43±0.02)kg/m~3),and total sulfur(TS,(0.69±0.11)kg/m~3)in the S.alterniflora marsh exceeded those in the adjacent bare mudflat,Suaeda salsa marsh,and Phragmites australis marsh.Because of its greater biomass,plant C((1193.7±133.6)g/m~2),N((18.8±2.4)g/m~2),and S((9.4±1.5)g/m~2)storage of S.alterniflora was also larger than those of co-occurring native plants.More biogenic elements circulated in the soil-plant system of the S.alterniflora marsh,and their spatial and temporal distribution patterns were also changed by the S.alterniflora invasion.Soil properties changed by S.alterniflora’s invasion thereby indirectly affected the accumulation of soil C,N and S in this wetland ecosystem.The SOC,TN,and TS contents were positively correlated with soil electrical conductivity and moisture,but negatively correlated with the pH and bulk density of soil.Together,these results indicate that S.alterniflora invasion altered ecosystem processes,resulted in changes in net primary production and litter decomposition,and increased the soil C,N and S storage capacity in the invaded ecosystems in comparison to those with native tallgrass communities in the coastal wetlands of East China. 展开更多
关键词 coastal WETLAND plant invasion SPARTINA alterniflora SOIL CARBON SOIL NITROGEN SOIL SULFUR
在线阅读 下载PDF
Dynamic Changes of Tobacco-growing Soil Nutrients and Enzymes After Application of Amelioration Materials 认领
13
作者 Zhanghong CAO Gexuan SU +8 位作者 Yongjun LIU Shuguang PENG Yongsheng DENG Jin CHEN Deyuan PENG Zhenghua WANG Jingjing WU Qianping YAN Xiaohua DENG 《农业生物技术:英文版》 CAS 2020年第4期87-91,共5页
[Objectives]This study was conducted to clarify the improvement effects of different soil amelioration materials such as lime,green manure and bio-organic fertilizer on acidic tobacco-planting soil.[Methods]The dynami... [Objectives]This study was conducted to clarify the improvement effects of different soil amelioration materials such as lime,green manure and bio-organic fertilizer on acidic tobacco-planting soil.[Methods]The dynamic changes of soil pH,soil nutrients and enzyme activity were studied by applying lime,lime+green fertilizer,and lime+green fertilizer+biological organic fertilizer.[Results]①After the application of amelioration materials,the soil pH and available phosphorus content of tobacco-growing soil showed a stepwise change of first increasing and then decreasing,and became stable at 60 d after tobacco transplanting;the soil organic matter,alkali-hydrolyzable nitrogen and available potassium content showed a gradual change trend of"high-low-high";and the soil invertase and urease activity showed a gradual change trend of"low-high-low".②To 90 d after tobacco transplanting,the application of amelioration materials increased soil pH by 1.29-1.62 units,and increased organic matter content by 15.21%-20.86%,alkali-hydrolyzable nitrogen content by 6.83%-18.17%,available phosphorus content by 54.15%-217.85%,rapidly available potassium content by 11.42%-30.86%,soil invertase activity by 70.09%-18.93%,and soil urease activity by 64.07%-130.47%.③The combination of lime+green manure+alkaline microbial organic fertilizer had the best effect on the improvement of acidic tobacco-growing soil,and the effect of lime+green manure+acid microbial organic fertilizer on acidic soil was the second.[Conclusions]When applying lime,green fertilizer and alkaline bio-organic fertilizer should be applied to achieve sustainable improvement of strongly acidic soil. 展开更多
关键词 Amelioration materials Soil pH Main nutrients of tobacco-growing soil Soil enzymes
在线阅读 下载PDF
Response of soil respiration to nitrogen addition in two subtropical forest types 认领
14
作者 Wende YAN Xiaoyong CHEN +3 位作者 Yuanying PENG Fan ZHU Wei ZHEN Xuyuan ZHANG 《土壤圈:英文版》 SCIE CAS CSCD 2020年第4期478-486,共9页
Anthropogenic activities have increased nitrogen(N)deposition in terrestrial ecosystems,which directly and indirectly affects soil biogeochemical processes,including soil respiration.However,the effects of the increas... Anthropogenic activities have increased nitrogen(N)deposition in terrestrial ecosystems,which directly and indirectly affects soil biogeochemical processes,including soil respiration.However,the effects of the increases in N availability on soil respiration are not fully understood.In this study,soil respiration was measured using an infrared gas analyzer system with soil chambers under four N treatments(0,5,15,and 30 g Nm^-2 year^-1 as control,low N(LN),moderate N(MN),and high N(HN),respectively)in camphor tree and slash pine forests in subtropical China.Results showed that soil respiration rates decreased by 37% in the camphor tree forest and 27% in the slash pine forest on average on an annual base,respectively,in the N-fertilized treatments when compared with the control.No significant differences were found in the soil respiration rate among the LN,MN,and HN treatments in both forest types as these fertilized plots reached an adequate N content zone.In addition,soil microbial biomass carbon(C)content and fine root biomass declined in N-treated plots compared to the control.Our results indicated that elevated N deposition might alter the tree growth pattern,C partitioning,and microbial activity,which further affect soil C sequestration by reducing soil respiration in subtropical forests of China. 展开更多
关键词 camphor tree forest fine root slash pine forest soil microbial biomass soil moisture soil temperature
Combined effects of soil texture and machine operating trail gradient on changes in forest soil physical properties during ground-based skidding 认领
15
作者 Ramin NAGHDI Ahmad SOLGI +1 位作者 Eric R.LABELLE Mehrdad NIKOOY 《土壤圈:英文版》 SCIE CAS CSCD 2020年第4期508-516,共9页
Wood extraction by heavy machinery has always been associated with soil disturbance in mountain forests,and the degree of soil degradation is influenced by several factors,including site and soil characteristics,soil ... Wood extraction by heavy machinery has always been associated with soil disturbance in mountain forests,and the degree of soil degradation is influenced by several factors,including site and soil characteristics,soil moisture,type of equipment used,and number of machine passes.The effects of ground-based skidding operations on the physical properties of soils with different texture were evaluated at different levels of traffic frequency and trail gradient at two sites in an Iranian temperate forest.The treatments included combinations of three different traffic frequencies(3,8,and 14 passes of a rubber-tired cable skidder),three levels of trail gradient(<10%,10%–20%,and>20%) and two soil texture classes,clay loam(Site 1) and sandy loam(Site 2).The average gravimetric soil moisture at the time of skidding was 23%(Site 1) and 20%(Site 2).The average dry bulk density and total porosity of the undisturbed soil(control) were0.71 g cm-3 and 73.3% at Site 1(clay loam) and 0.86 g cm-3and 59.1% at Site 2(sandy loam),respectively.At site 1(fine-textured soil),rutting began after three passes of the skidder,whereas at site 2(coarse-textured soil),rutting occurred only after eight passes.Independent of the traffic frequency and trail gradient,machine impact on the fine-textured soil caused greater increases in bulk density and rut depth compared to that on the coarse-textured soil.After three skidder passes and independent from trail gradients,dry bulk density at Site 1 increased by 54.8% compared to that of the undisturbed control,and the increase was 45.5% at Site 2.Therefore,medium to fine-textured soils are more susceptible to compaction than coarse-textured soils.Such soils,especially when moist,should be protected using brush mats created from harvesting residues during the forest processing phase. 展开更多
关键词 bulk density forest processing RUTTING soil compaction soil disturbance soil type total porosity
土壤的教育价值——基于自然和文化的视角 认领
16
作者 李长伟 宋以国 《教育理论与实践》 北大核心 2020年第16期3-9,共7页
现代工业文明的飞速发展使得作为生态环境核心和多元文化基础的土壤资源遭到严重破坏,而作为环境教育核心和乡土教育基础的土壤却始终被当下的教育实践所忽视,其自身所蕴含的丰富的教育价值不被教育参与者所重视。这主要体现在土壤在学... 现代工业文明的飞速发展使得作为生态环境核心和多元文化基础的土壤资源遭到严重破坏,而作为环境教育核心和乡土教育基础的土壤却始终被当下的教育实践所忽视,其自身所蕴含的丰富的教育价值不被教育参与者所重视。这主要体现在土壤在学校课程体系中的退场、以土壤为基础的乡土文化的失落以及社会公众土壤意识的缺乏。改变土壤教育资源在教育中的"缄默"现状,充分挖掘土壤所蕴含的教育价值,应该更新文化观念——营造土壤文化,转变教育思想——关注人类生存前景,强化教育实践——创设土壤课程。 展开更多
关键词 土壤 教育价值 自然 文化 土壤文化 土壤课程
Regions and Their Typical Paradigms for Soil and Water Conservation in China 认领
17
作者 DANG Xiaohu SUI Boyang +5 位作者 GAO Siwen LIU Guobin WANG Tao WANG Bing NING Duihu BI Wei 《中国地理科学:英文版》 SCIE CSCD 2020年第4期643-664,共22页
China is experiencing conflicts between its large population and scarce arable land,and between a demand for high productivity and the severe soil erosion of arable land.Since 1949,China has committed to soil and wate... China is experiencing conflicts between its large population and scarce arable land,and between a demand for high productivity and the severe soil erosion of arable land.Since 1949,China has committed to soil and water conservation(SWC),for which eight regions and 41 subregions have been developed to improve the environment and increase land productivity.To obtain information from the regional planning and strategies for SWC and to explore whether SWC practices simultaneously contribute to soil conservation,ecosystem functioning,and the livelihoods of local farmers,and to summarize the successful experiences of various SWC paradigms with distinct characteristics and mechanisms of soil erosion,this paper systematically presents seven SWC regions(excluding the Tibetan Plateau region)and 14 typical SWC paradigms,focusing on erosion mechanisms and the key challenges or issues in the seven regions as well as on the core problems,main objectives,key technologies,and the performance of the 14 typical paradigms.In summary,the 14 typical SWC paradigms successfully prevent and control local soil erosion,and have largely enhanced,or at least do not harm,the livelihoods of local farmers.However,there remain many challenges and issues on SWC and socioeconomic development that need to be addressed in the seven SWC regions.China,thus,still has a long way to go in successfully gaining the win-win objective of SWC and human aspects of development. 展开更多
关键词 regions for soil and water conservation soil erosion dryland farming collapse erosion karst rocky desertification typical paradigm for soil and water conservation
在线阅读 下载PDF
Effects of reduced nitrogen and suitable soil moisture on wheat(Triticum aestivum L.) rhizosphere soil microbiological,biochemical properties and yield in the Huanghuai Plain,China 认领
18
作者 ZHOU Su-mei ZHANG Man +4 位作者 ZHANG Ke-ke YANG Xi-wen HE De-xian YIN Jun WANG Chen-yang 《农业科学学报:英文版》 SCIE CAS CSCD 2020年第1期234-250,共17页
Soil management practices affect rhizosphere microorganisms and enzyme activities, which in turn influence soil ecosystem processes. The objective of this study was to explore the effects of different nitrogen applica... Soil management practices affect rhizosphere microorganisms and enzyme activities, which in turn influence soil ecosystem processes. The objective of this study was to explore the effects of different nitrogen application rates on wheat(Triticum aestivum L.) rhizosphere soil microorganisms and enzyme activities, and their temporal variations in relation to soil fertility under supplemental irrigation conditions in a fluvo-aquic region. For this, we established a split-plot experiment for two consecutive years(2014–2015 and 2015–2016) in the field with three levels of soil moisture: water deficit to no irrigation(W1), medium irrigation to(70±5)% of soil relative moisture after jointing stage(W2), and adequate irrigation to(80±5)% of soil relative moisture after jointing stage(W3);and three levels of nitrogen: 0 kg ha^–1(N1), 195 kg ha^–1(N2) and 270 kg ha^–1(N3). Results showed that irrigation and nitrogen application significantly increased rhizosphere microorganisms and enzyme activities. Soil microbiological properties showed different trends in response to N level;the highest values of bacteria, protease, catalase and phosphatase appeared in N2, while the highest levels of actinobacteria, fungi and urease were observed in N3. In addition, these items performed best under medium irrigation(W2) relative to W1 and W3;particularly the maximum microorganism(bacteria, actinobacteria and fungi) amounts appeared at W2, 5.37×10^7 and 6.35×10^7 CFUs g^–1 higher than those at W3 in 2014–2015 and 2015–2016, respectively;and these changes were similar in both growing seasons. Microbe-related parameters fluctuated over time but their seasonality did not hamper the irrigation and fertilization-induced effects. Further, the highest grain yields of 13 309.2 and 12 885.7 kg ha^–1 were both obtained at W2 N2 in 2014–2015 and 2015–2016, respectively. The selected properties, soil microorganisms and enzymes, were significantly correlated with wheat yield and proved to be valuable indicators of soil qualit 展开更多
关键词 suitable SOIL moisture nitrogen-reduction RHIZOSPHERE SOIL microorganisms RHIZOSPHERE SOIL enzyme activity winter wheat(Triticum AESTIVUM L.)
在线阅读 下载PDF
A modified soil water content measurement technique using actively heated fiber optic sensor 认领
19
作者 Meng Wang Xu Li +3 位作者 Lihong Chen Senquan Hou Guiyan Wu Zhilin Deng 《岩石力学与岩土工程学报:英文版》 SCIE CSCD 2020年第3期608-619,共12页
Soil water content measurement is critical in practical engineering.The actively heated fiber Bragg grating optic sensor(FBGS)has great potential of multi-point measurement for soil water content measurement in field.... Soil water content measurement is critical in practical engineering.The actively heated fiber Bragg grating optic sensor(FBGS)has great potential of multi-point measurement for soil water content measurement in field.In this study,the effect of heating time on the measurement accuracy is discussed,and modifications are made for actively heated fiber optic(AHFO)sensors.The results demonstrate that if an integration data analysis method is used,the accuracy and reliability of soil water content measurement with AHFO sensors will be improved.Both a short fiber length and a short-term heating pattern are effective and can help to reduce soil disturbance.With the proposed integration method,a short heating time is guaranteed for measuring the soil water content.Such improvements will reduce the thermal disturbance to soil sample and improve the reliability of measurement. 展开更多
关键词 Fiber bragg grating Carbon fiber heated sensor Unsaturated soil Field monitoring Soil water content measurement
在线阅读 下载PDF
Critical state model for structured soil 认领
20
作者 Cristhian Mendoza Marcio Muniz de Farias 《岩石力学与岩土工程学报:英文版》 SCIE CSCD 2020年第3期630-641,共12页
Structure is an evident determinant for macroscopic behaviors of soils.However,this is not taken into account in most constitutive models,as structure is a rather complex issue in models.For this,it is important to de... Structure is an evident determinant for macroscopic behaviors of soils.However,this is not taken into account in most constitutive models,as structure is a rather complex issue in models.For this,it is important to develop and implement simple models that can reflect this important aspect of soil behavior.This paper tried to model structured soils based on well-established concepts,such as critical state and sub-loading.Critical state is the core of the classic Cam Clay model.The sub-loading concept implies adoption of an inner(sub-loading)yield surface,according to specific hardening rules for some internal strain-like state variables.Nakai and co-workers proposed such internal variables for controlling density(p)and structure(ω),using a modified stress space,called tij.Herein,similar variables are used in the context of the better-known invariants(p and q)of the Cam Clay model.This change requires explicit adoption of a non-associated flow rule for the sub-loading surface.This is accomplished by modifying the dilatancy ratio of the Cam Clay model,as a function of the new internal variables.These modifications are described and implemented under three-dimensional(3D)conditions.The model is then applied to simulating laboratory tests under different stress paths and the results are compared to experiments reported for different types of structured soils.The good agreements show the capacity and potential of the proposed model. 展开更多
关键词 Elastoplasticity Cam clay with sub-loading Structured soil Tropical soil Non-associated flow rule
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈