A GIS-based Tupu Analysis of Dynamics of Saline-alkali Land in Western Jilin Province

Based on Tupu theory, this paper studied the dynamic changes, conversion modes, expansion intensity and landscape attributes of the saline-alkali lands in Changling County, Zhenlai County and Da'an City of the western Jilin Province in 1980-2000 with the help of GIS. The results show that the saline-alkali land rather sharply increased in Da'an during 1995-2000; the main conversion processes in the three counties were from grassland to saline-alkali land and from saline-alkali land to grassland; and the typical shapes, spatial expansion speed and mode, and landscape attributes of the saline-alkali land were different in the three counties, which were closely related to local topography, predominant wind orientation, water resources distribution, etc. The corresponding spatial expansion mode was marginality in Changling, random in Zhenlai and more kernels in Da'an, respectively. Landscape attributes also responded to the spatial-temporal dynamic changes of the saline-alkali land and the landscape indices of Da'an fluctuated greatly. The frame of this research may provide fundamental reference for landscape analysis and give some suggestions for regional sustainable development.     

青州市南张楼村土地质量地球化学特征及特色土地资源评价

本文以青州市南张楼村为研究区,基于村级土地质量地球化学调查数据,开展土壤养分、土壤环境、土壤质量及特色土地资源评价。结果显示,土壤养分N以较缺乏、中等为主;P以丰富为主;K以中等、较丰富为主;土壤养分地球化学综合等级以较丰富为主,土壤养分总体水平较好。土壤环境单指标Zn存在小面积的污染风险,污染等级为风险可控,其他指标均为无风险,土壤环境地球化学综合等级以无风险为主,土壤环境清洁。土壤质量地球化学综合等级以一等(优质)和二等(良好)为主,土壤质量优良。本次研究共发现耕地富硒土壤0.08km²、富锗土壤0.93km²,富锌土壤3.61km²,表明研究区特色土地资源丰富。     

The effect of land use changes on soil conditions in arid region

Biography:CHEN Fu(1974－ ), male,a native of Sheyang County, Jiangsu Province, doctoral candidate.His research interests include land use management.1 INTRODUCTION Land use change may influence a variety of natural and ecological processes, including soil nutrient, soil moisture, soil erosion, land productivity (FU et al., 1999), biodiversity, cycle of biographical geochemistry, and so on (VITOUSEK, 1994). So, it is very important that the studies of land use changes understand re…     

DESIGN AND COMPILATION OF AGRICULTURAL ELECTRONIC ATLAS AT COUNTY-LEVEL

１ＩＮＴＲＯＤＵＣＴＩＯＮＷｉｔｈｔｈｅｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔａｎｄａｐｐｌｉｃａｔｉｏｎｏｆｎｅｗｔｅｃｈｎｉｑｕｅｓｓｕｃｈａｓｃｏｍｐｕｔｅｒｃａｒｔｏｇｒａｐｈｙｈａｓｅｎｔｅｒｅｄｔｈｅ２１ｓｔｃｅｎｔｕｒｙ′ｓｄｉｇｉｔａｌｐｅｒｉｏｄｆｒｏｍｃｏｍｐｕｔｅｒａｓｓｉｓｔｍａｐｐｉｎｇｉｎｔｈｅ１９７０ｓｔｒａｄｉｔｉｏｎａｌｍａｐｒｅｐｒｅｓｅｎｔａｔｉｏｎｈａｓｔｒａｎｓｆｏｒｍｅｄｆｒｏｍ２Ｄｍｏｎｏｍｅｄｉｕｍｓｔａｔｉｃｉｎｔｏ３Ｄｍｕｌｔｉｍ…     

山东省临沭县北部土壤养分特征及综合肥力评价

在山东省临沭县北部农耕区进行耕层土壤样品采集,并测定土壤pH、有机质、全量及速效氮磷钾等养分指标来表征土壤肥力,运用因子分析法、聚类分析法计算出所有样本土壤养分综合评价值并进行等级划分来评价土壤肥力。结果表明临沭县北部土壤酸化严重,有机质和全氮、速效钾含量较低,全钾、全磷、碱解氮、速效磷比较丰富。因子分析显示TN、OM、AK、AP、TP、pH是影响临沭县北部土壤养分综合状况的主要因素。临沭县北部土壤肥力水平偏低;土壤养分综合评价值(IFI)具体表现为：郑山街道>青云镇>玉山镇>临沭街道>蛟龙镇。     

Influence of livestock soil eutrophication on floral composition in the Pyrenees mountains

Livestock behaviour in the Pyrenees includes free grazing and a long resting period that provokes the accumulation of dung and urine in some places,so-called camping areas. The aims of this study were （i） to analyze any change in floral composition,and in nutritional and chemical contents of plants in a livestock camping area; and （ii） to relate the floral composition with soil chemical properties. In a linear transect,five sampling zones were established,from the centre of the camping area to the surrounding Nardus stricta-dominant pasture. The above ground plant biomass and the topsoil were sampled in each zone with 6 replicates per zone. Plant species were classified and weighed to calculate above ground biomass,nutritional and chemical contents,and Shannon diversity and evenness indices. Additionally,soils were sampled in two periods,at the beginning and at the end of grazing period. Soil available nutrients （nitrate,ammonium,phosphorus,potassium,calcium and magnesium）,total nitrogen,organic carbon and pH were measured.
Plant chemical contents （protein,lignin and others） were significantly related to the proportions of grasses,legumes and other plants; so,the protein content is positively correlated with legumes plant biomass while lignin content is negatively correlated with grasses. Both plant and soil nutrients increased linearly towards the centre of the camping area. However,the relationship among plant species richness,diversity and evenness relative to its position along the studied transect was bell-shaped. From the outskirts to the centre of the camping area,plants with low nutrient demand were progressively replaced by those with medium and high nutrients demand and by pioneers.
Nardus stricta-dominant pasture has low plant diversity and plant nutrient content as well as a poor soil nutrient availability. The presence of the camping area introduced patches with more soil nutrients and new species in the large spatial scale. However at a small spatial scale,the strong soil nutrien     

Changes in SOC and nutrients under intensive tillage in two types of slope landscapes

The net effect of tillage erosion on soil properties would be associated with the spatial variation in soil constituents,and therefore plays an important role in ecological agriculture.We conducted a consecutive tillage by hoeing 15 times during a period with no rainfall in the two slope landscapes(a linear slope and complex slope) of the Yangtze Three Gorges reservoir areas,to examine the relationship between soil erosion rates and the variations in soil chemical properties and compare the effects of soil redistribution on SOC and nutrients between the linear and complex slopes.After the simulated tillage,notable changes in 137 Cs inventories of the soil occurred in the summit and toeslope positions on the linear slope,while there were significant changes in 137 Cs inventories at convex and concave positions on the complex slope.Soil profile disappeared at the summit slope boundary,with the exposure area of 16.0% and 7.6% of the experimental plot,respectively,for the linear and complex slopes due to no soil replacement.Soil organic C and nutrients were completely depleted with the disappearance of soil profiles at soil eroding zones,whereas a remarkable increase in SOC,total N and available nutrient concentrations of the post-tillage surface soil and a decrease in total nutrient concentrations(P and K) were found at depositional zones on the linear slope.For the complex slope,however,changes in SOC and nutrient concentrations of the post-tillage surface soil exhibited a patterndifferent from that on the linear slope,which showed a remarkable decrease in SOC and total nutrient concentrations but a slight increase in available nutrient concentrations after tillage in the toeslope position.Due to the gradual increase in soil depth from top to bottom of the slope,SOC and nutrient inventories in the soil profiles were significantly correlated with soil redistribution rates on both the linear and complex slopes.Tillage causes remarkable changes of soil chemical properties in the surface soil layer and soil profile,and increases SOC and nutrient inventories for the soil profile downslope in steeply sloping landscapes.     

福州市农田土壤养分空间变异特征

研究农田土壤养分空间分布特征及变异规律,分析地形因子对土壤养分空间分布的影响,对土壤养分的有效利用与管理具有重要意义。本文采用GIS和地统计学相结合的方法,揭示东南丘陵区福州市农田土壤养分（有机质、碱解氮、有效磷和速效钾）的空间分布特征和变异规律,并进一步探讨土壤养分含量与地形因子（地形起伏度、高程、地形湿度指数、沉积运输指数和坡度）之间的相关性。结果表明：福州市农田有机质、碱解氮、有效磷和速效钾含量范围分别为1.10~89.5 g/kg、 1.00~461 mg/kg、0.300~298 mg/kg、和4.00~399 mg/kg,其变异系数范围为35.3%~99.0%,均属于中等变异水平;区域内耕地土壤养分存在明显的空间丰缺差异,大部分地区有机质和有效磷含量较为丰富,碱解氮含量处于中等偏上水平,速效钾含量相对较低;有机质、碱解氮、有效磷和速效钾的块金系数分别为32.0%、37.3%、50.0%和50.0%,均呈中等强度空间自相关,表明同时受到结构和随机因素控制;有机质和碱解氮空间自相关尺度较大,且在步长小于0.3 km时,各方向（0°、45°、90°和135°）变化平稳,为各向同性,而有效磷和速效钾变程较小,且各方向变化较复杂,为各向异性。这些结果表明,政府需加强施肥指导,保持氮肥施用量的同时,合理增加钾肥,适当降低有机肥和磷肥施用。此外,在后续调查采样时,样点布设要考虑密度和方向性,适当加密有效磷和速效钾的采样,而有机质和碱解氮采样可以在此基础上适当减少样点。     

Impacts of soil fauna on litter decomposition at different succession stages of wetland in Sanjiang Plain, China

Litter decomposition is the key process in nutrient recycling and energy flow. The present study examined the impacts of soil fauna on decomposition rates and nutrient fluxes at three succession stages of wetland in the Sanjiang Plain, China using different mesh litterbags. The results show that in each succession stage of wetland, soil fauna can obviously increase litter decomposition rates. The average contribution of whole soil fauna to litter mass loss was 35.35%. The more complex the soil fauna group, the more significant the role of soil fauna. The average loss of three types of litter in the 4mm mesh litterbags was 0.3–4.1 times that in 0.058mm ones. The decomposition function of soil fauna to litter mass changed with the wetland succession. The average contribution of soil fauna to litter loss firstly decreased from 34.96% (Carex lasiocapa) to 32.94% (Carex meyeriana), then increased to 38.16% (Calamagrostics angustifolia). The contributions of soil fauna to litter decomposition rates vary according to the litter substrata, soil fauna communities and seasons. Significant effects were respectively found in August and July on C. angustifolia and C. lasiocapa, while in June and August on C. meyeriana. Total carbon (TC), total nitrogen (TN) and total phosphorus (TP) contents and the C/N and C/P ratios of decaying litter can be influenced by soil fauna. At different wetland succession stages, the effects of soil fauna on nutrient elements also differ greatly, which shows the significant difference of influencing element types and degrees. Soil fauna communities strongly influenced the TC and TP concentrations of C. meyeriana litter, and TP content of C. lasiocapa. Our results indicate that soil fauna have important effects on litter decomposition and this influence will vary with the wetland succession and seasonal variation. Foundation item: Under the auspices of State Key Development Program for Basic Research of China (No. 2009CB421103), Key Program of National Natural Science Foundation of China (No. 40830535/D0101), Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-BR-16, KSCX2-YW-N-46-06)     

Agricultural Land Suitability of Production Space in the Taihang Mountains,China

The contradiction between the shortage of land for agriculture due to rapid expansion of industrialization and urbanization and increasing population pressure is projected to impose great threats to future food security.Agricultural land suitability evaluation is an effective approach to improve the utilization of land resources for crop production and thus enhance the capacity of food provision.In this study, we evaluated the land suitability for agriculture of the production space in the Taihang Mountains by three steps: establishing indicator system, determining weights for indicators, and constructing a fuzzy matter-element model to assess the grades of suitability.Results showed that the land suitability had a significant linear correlation with potential crop yields, indicating our evaluation was effective to predict crop production.The spatial pattern of land suitability for crop production demonstrated that land with higher suitability was generally located in piedmont plains and basins, while land with lower suitability was mostly situated in mountainous areas.The area of highly, moderately, marginally suitable and unsuitable land for agriculture was 32.13%, 28.58%, 37.49% and 1.80% of the production space, respectively.However, the correlation degree analysis indicated that the requirements of these four suitability grades were currently not satisfied but could be potentially fulfilled.In terms of indicator weights, soil properties were much more important than topography and location conditions to influence the grades of suitability.Among all indicators, slope, soil organic matter, soil texture and soil depth were the most influential factors, so slope farming prevention and organic fertilization were most likely to improve land suitability for agriculture.Compared the outputs of our land suitability evaluation model with the distribution of the existing croplands, we found that about 66.52% of marginally suitable and 54.55% of unsuitable land for agriculture were currently used for croplands.Therefore, de-farming policy should be implemented in areas of these two suitability grades.In contrast, cropland expansion was encouraged in the land that was highly or moderately suitable for agriculture.Our evaluation of agricultural land suitability is beneficial for future land use planning and decision-making in the Taihang Mountains.     

土地质量地球化学评价数据库建库方法探讨——以章丘市刁镇和辛寨镇为例

土地质量地球化学评价数据库是以土壤地球化学调查为主,同时开展大气干(湿)沉降物、灌溉水、化肥及农作物等介质的地球化学调查数据和分析数据资料为基础,利用MapGIS软件管理编制成果图件;利用Access数据库管理规范成果数据;利用中国地调局发展研究中心下发的《土地质量地球化学调查与评价数据录入子系统》将数据资料数字化,从而建立评价数据库。数据库内容包括区域地理地质、地形地貌、土壤类型及土地利用等基础空间数据库;包括采样介质的工作区采样布置、单元素地球化学图、土壤元素分级图及大气环境、灌溉水环境、土壤质量、土地质量综合等级图为核心的空间评价数据库;包括土地规划图、特色农产品种植规划建议图、施肥建议图等各种成果图件。数据库实现了对样品及相应的众多的化验分析数据的科学有效的管理,便于数据的统一保存、分析和使用,为评价区土地质量地球化学调查评价和总体综合研究提供了基础资料,为促进农业经济规划调整,现代绿色农业发展和优化、特色土地资源开发与利用提供重要依据。     

Examination of Silicate Limitation of Primary Production in Jiaozhou Bay,North China：Ⅲ.Judgment Method ,Rules and Uniqueness of Nutrient Limitation Among N,P,and Si

Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994 (12 seasonal investigations) provided by the Ecological Station of Jiaozhou Bay revealed the characteristic spatiotemporal variation of the ambient concentration Si∶DIN and Si∶16P ratios and the seasonal variation of Jiaozhou Bay Si∶DIN and Si∶16P ratios showing that the Si∶DIN ratios were <1 throughout the year in Jiaozhou Bay; and that the Si∶16P ratios were <1 throughout Jiaozhou Bay in spring, autumn and winter. The results proved that silicate limited phytoplankton growth in spring, autumn and winter in Jiaozhou Bay. Analysis of the Si∶DIN and Si∶P ratios showed that the nutrient Si has been limiting the growth of phytoplankton throughout the year in some Jiaozhou Bay waters; and that the silicate deficiency changed the phytoplankton assemblage structure. Analysis of discontinuous 1962 to 1998 nutrient data showed that there was no N or P limitation of phytoplankton growth in that period. The authors consider that the annual cyclic change of silicate limits phytoplankton growth in spring, autumn and winter every year in Jiaozhou Bay; and that in many Jiaozhou Bay waters where the phytoplankton as the predominant species need a great amount of silicate, analysis of the nutrients N or P limitation of phytoplankton growth relying only on the N and P nutrients and DIN∶P ratio could yield inaccurate conclusions. The results obtained by applying the rules of absolute and relative limitation fully support this view. The authors consider that the main function of nutrient silicon is to regulate and control the mechanism of the phytoplankton growth process in the ecological system in estuaries, bays and the sea. The authors consider that according to the evolution theory of Darwin, continuous environmental pressure gradually changes the phytoplankton assemblage's structure and the physiology of diatoms. Diatoms requiring a great deal of silicon either constantly decrease or reduce their requirement for silicon. This will cause a series of huge changes in the ecosystem so that the whole ecosystem requires continuous renewal, change and balancing. Human beings have to reduce marine pollution and enhance the capacity of continental sources to transport silicon to sustain the continuity and stability in the marine ecosystem. This study was funded by the NSFC (No. 40036010) and subsidized by Special Funds from the National Key Basic Research Program of P. R. China (G199990437), the Postdoctoral Foundation of Ocean University of Qingdao, the Director's Foundation of the Beihai Monitoring Center of the State Oceanic Administration and the Foundation of Shanghai Fisheries University.     

Soil organic carbon pools in particle-size fractions as affected by slope gradient and land use change in hilly regions, western Iran

This study was conducted to explore the effects of topography and land use changes on particulate organic carbon(POC),particulate total nitrogen(PTN),organic carbon(OC) and total nitrogen(TN) associated with different size primary particle fractions in hilly regions of western Iran.Three popular land uses in the selected site including natural forest(NF),disturbed forest(DF) and cultivated land(CL) and three slope gradients(0-10 %,S1,10-30 %,S2,and 30-50%,S3) were employed as the basis of soil sampling.A total of 99 soil samples were taken from the 0-10 cm surface layer in the whole studied hilly region studied.The results showed that the POC in the forest land use in all slope gradients was considerably more than the deforested and cultivated lands and the highest value was observed at NF-S1 treatment with 9.13%.The values of PTN were significantly higher in the forest land use and in the down slopes(0.5%) than in the deforested and cultivated counterparts and steep slopes(0.09%) except for the CL land use.The C:N ratios in POC fraction were around 17-18 in the forest land and around 23 in the cultivated land.In forest land,the silt-associated OC was highest among the primary particles.The enrichment factor of SOC,EC,was the highest for POC.For the primary particles,EC of both primary fractions of silt and clay showed following trend for selected land uses and slope gradients:CL> DF> NF and S3 > S2> S1.Slope gradient of landscape significantly affected the OC and TN contents associated with the silt and clay particles,whereas higher OC and TN contents were observed in lower positions and the lowest value was measured in the steep slopes.Overall,the results showed that native forest land improves soil organic carbon storage and can reduce the carbon emission and soil erosion especially in the mountainous regions with high rainfall in west of Iran.     

山东省茌平县土壤元素地球化学特征与质量评价

以茌平县土壤为研究对象,通过系统的地球化学调查,获取了土壤20余项指标含量数据;在此基础上计算了茌平县土壤中背景值和基准值等系列地球化学参数,圈定地球化学异常区,评价了土壤养分和环境地球化学等级、土壤质量地球化学综合等级。结果表明,与山东省土壤背景值平均值相比,茌平县土壤中K、Mn、Pb、V、Mo、I等元素偏低,而有机质、As、Cd、Hg、B等元素偏高。调查区7类异常区域均有分布;土壤质量综合评价以优质等级为主,约占全区面积的73.96%,良好等级约占全区面积的24.67%。     

Responses of Dodonaea viscosa growth and soil biological properties to nitrogen and phosphorus additions in Yuanmou dry-hot valley

Nitrogen(N) and phosphorus(P) are limited nutrients in terrestrial ecosystems, and their limitation patterns are being changed by the increase in N deposition. However, little information concerns the plant growth and the soil biological responses to N and P additions among different soils simultaneously, and these responses may contribute to understand plant-soil interaction and predict plant performance under global change. Thus, this study aimed to explore how N and P limitation changes in different soil types, and reveal the relationship between plant and soil biological responses to nutrient additions. We planted Dodonaea viscosa, a globally distributed species in three soil types(Lixisols, Regosols and Luvisols) in Yuanmou dry-hot valley in Southwest China and fertilized them factorially with N and P. The growth and biomass characters of D. viscosa, soil organic matter, available N, P contents and soil carbon(C), N, P-related enzyme activities were quantified. N addition promoted the growth and leaf N concentration of D. viscosa in Lixisols; N limitation in Lixisols was demonstrated by lower soil available N with higher urease activity. P addition promoted the growth and leaf P concentration of D. viscosa in Luvisols; severe P limitation in Luvisols was demonstrated by a higher soil available N: P ratio with higher phosphatase activity. Urease activity was negatively correlated with soil available N in Nlimited Lixisols, and phosphatase activity was negatively correlated with soil available P in P-limited Luvisols. Besides, the aboveground biomass and leaf N concentration of D. viscosa were positively correlated with soil available N in Lixisols, but the aboveground biomass was negatively correlated with soil available P. Our results show similar nutrient limitation patterns between plant and soil microorganism in the condition of enough C, and the nutrient limitations differ across soil types. With the continued N deposition, N limitation of the Lixisols in dry hot valleys is expected to be alleviated, while P limitation of the Luvisols in the mountaintop may be worse in the future, which should be considered when restoring vegetation.     

Decreasing nutrient concentrations in soils and trees with increasing elevation across a treeline ecotone in Rolwaling Himal,Nepal

At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen (N), magnesium (Mg), potassium (K), and foliar phosphorus (P) decrease significantly with elevation. Foliar manganese (Mn) concentrations, by contrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.     

Responses of <Emphasis Type="Italic">Dodonaea viscosa</Emphasis> growth and soil biological properties to nitrogen and phosphorus additions in Yuanmou dry-hot valley

Nitrogen (N) and phosphorus (P) are limited nutrients in terrestrial ecosystems, and their limitation patterns are being changed by the increase in N deposition. However, little information concerns the plant growth and the soil biological responses to N and P additions among different soils simultaneously, and these responses may contribute to understand plant-soil interaction and predict plant performance under global change. Thus, this study aimed to explore how N and P limitation changes in different soil types, and reveal the relationship between plant and soil biological responses to nutrient additions. We planted Dodonaea viscosa, a globally distributed species in three soil types (Lixisols, Regosols and Luvisols) in Yuanmou dry-hot valley in Southwest China and fertilized them factorially with N and P. The growth and biomass characters of D. viscosa, soil organic matter, available N, P contents and soil carbon (C), N, P-related enzyme activities were quantified. N addition promoted the growth and leaf N concentration of D. viscosa in Lixisols; N limitation in Lixisols was demonstrated by lower soil available N with higher urease activity. P addition promoted the growth and leaf P concentration of D. viscosa in Luvisols; severe P limitation in Luvisols was demonstrated by a higher soil available N: P ratio with higher phosphatase activity. Urease activity was negatively correlated with soil available N in Nlimited Lixisols, and phosphatase activity was negatively correlated with soil available P in P-limited Luvisols. Besides, the aboveground biomass and leaf N concentration of D. viscosa were positively correlated with soil available N in Lixisols, but the aboveground biomass was negatively correlated with soil available P. Our results show similar nutrient limitation patterns between plant and soil microorganism in the condition of enough C, and the nutrient limitations differ across soil types. With the continued N deposition, N limitation of the Lixisols in dry hot valleys is expected to be alleviated, while P limitation of the Luvisols in the mountaintop may be worse in the future, which should be considered when restoring vegetation.     

章丘大葱特征元素农业地球化学研究

以章丘大葱产区生态地球化学调查为基础,采集了表层土壤、大葱、根系土及出露的代表性岩石样品,实测了大量和微量营养元素的含量,查明了研究区土壤地球化学背景。通过计算大葱对土壤营养元素的吸收率及大葱品质与营养元素的相关性分析,查明了大葱生长的特征营养元素为N,K2O,Zn,B,P,Cu,Mn。在岩石-土壤-大葱这一生态体系中,营养元素在土壤中保持一定的储备和积累,为大葱的生长提供了有利的农业地球化学环境。     

LAND-COVER DENSITY-BASED APPROACH TO URBAN LAND USE MAPPING USING HIGH-RESOLUTION IMAGERY

1IN T R O D U C T IO N Timely up-gradatnig ofurban landuse and landcoverin- formationisessentialforurban environmentalmonitor- ing,planningand management purposes.Traditionall,y fieldsurveyand visualinterpretatiofnrom aerialphotog- raphy areprimary ways t…     

Effects of land management practices on labile organic carbon fractions in rice cultivation

A research trial with four land management practices, i.e., traditional tillage-fallow (TTF), traditional tillage-wheat (TTW), conservation tillage-fallow (CTF) and conservation tillage-wheat (CTW), was sampled in the 15th year after its establishment to assess the effects of different management practices on labile organic carbon fractions (LOCFs), such as easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC), particulate organic carbon (POC) and microbial biomass carbon (MBC) in a typical paddy soil, Chongqing, Southwest China. The results indicated that LOCFs were significantly influenced by the combination of no-tillage, ridge culture and crop rotation. And, different combination patterns showed different effectiveness on soil LOCFs. The effects of no-tillage, ridge culture and wheat cultivation on EOC, DOC, POC and MBC mainly happened at 0–10cm. At this depth, soil under CTW had higher EOC, DOC, POC and MBC contents, compared to TTF, TTW and CTF, respectively. Moreover, the contents of LOCFs for different practices generally decreased when the soil depth increased. Our findings suggest that the paddy soil in Southwest China could be managed to concentrate greater quantities of EOC, DOC, POC and MBC. Foundation item: Under the auspices of Key Project of National Natural Science Foundation of China (No. 40231016)