Rhizosphere and bulk soil enzyme activities in a Nothotsuga longibracteata forest in the Tianbaoyan National Nature Reserve,Fujian Province,China

The rhizosphere, distinct from bulk soil, is defined as the volume of soil around living roots and influenced by root activities. We investigated protease, invertase, cellulase, urease, and acid phosphatase activities in rhizosphere and bulk soils of six Nothotsuga longibracteata forest communities within Tianbaoyan National Nature Reserve, including N. longibracteata ＋ either Phyllostachys pubescens, Schima superba, Rhododendron simiarum, Cunninghamia lanceolata, or Cyclobalanopsis glauca, and N. longibracteata pure forest. Rhizosphere soils possessed higher protease, invertase, cellulase, urease, and acid phosphatase activities than bulk soils. The highest invertase, urease, and acid phosphatase activities were observed in rhizosphere samples of N. longibracteata ＋ S. superba. Protease was highest in the N. longibracteata ＋ R. simiarum rhizosphere, while cellulase was highest in the pure N. longibracteata forest rhizosphere. All samples exhibited obvious rhizosphere effects on enzyme activities with a significant linear correlation between acid phosphatase and cellulase activities （p 〈 0.05） in rhizosphere soils and between protease and acid phosphatase activities （p 〈 0.05） in bulk soils. A principal component analysis, correlating 13 soil chemical properties indices relevant to enzyme activities, showed that protease, invertase, acid phosphatase, total N, and cellulase were the most important variables impacting rhizosphere soil quality.

Changes in bulk soil affect the disease-suppressive rhizosphere microbiome against Fusarium wilt disease

Harnessing disease suppressive microbiomes constitutes a promising strategy for optimizing plant growth.However,relatively lttle information is available about the relationship between bulk and rhizosphere soil microbiomes.Here,the assembly of banana bulk soil and rhizosphere microbiomes was investigated in a mono-culture system consisting of bio-organic(BIO)and organic management practices.Applying BIO practice in newly reclaimed fields resulted in a high-efficiency biocontrol rate,thus providing a promising strategy for pre-control of Fusarium wilt disease.The soil microbiota was further characterized by MiSeq sequencing and quantitative PCR.The results indicate that disease suppression was mediated by the structure of a suppressive rhizosphere microbiome with respect to distinct community composition,diversity and abundance.Overall microbiome suppressiveness was primarily related to a particular set of enriched bacterial taxa affiliated with Pseudomonas,Terrimonas,Cupriavi-dus,Gp6,Ohtaekwangia and Duganella.Finally,struc-tural equation modeling was used to show that the changes in bulk soil bacterial community determined its induced rhizosphere bacterial community,which serves as an important and direct factor in restraining the pathogen.Collectively,this study provides an integrative approach to disentangle the biological basis of disease-suppressive microbiomes in the context of agricultural practice and soil management.

Dynamic monitoring of soil bulk density and infiltration rate during coal mining in sandy land with different vegetation

To investigate the effects of coal mining on soil physical properties,sandy lands with three major vegetation types(Salix psammophila,Populus simonii,and Artemisia ordosica)were investigated by the ring knife method and double-ring infiltrometer.Specifically,variations in soil bulk density and water infiltration rate and the influences of coal mining and vegetation type on the properties during different subsidence stages were studied at the Shendong Bulianta mine.The results showed that,in the period before mining,soil bulk density occurred in the order A.ordosica>P.simonii>S.psammophila,with a negative correlation between the initial infiltration rate and steady infiltration rate being observed.In the period during mining and 3 months after mining,there were no significant differences in soil bulk density and water infiltration rate among vegetation types.At 1 year after mining,the soil bulk density occurred in the order A.ordosica>S.psammophila>P.simonii,having a negative correlation with the steady infiltration rate.The water infiltration depths of the S.psammophila,P.simonii and A.ordosica were 50,60,and 30 cm,respectively.The infiltration characters were simulated by the Kostiakov equations,and the simulated and experimental results were consistent.Linear regression revealed that vegetation types and soil bulk density had significant effects on soil initial infiltration rate during the four study periods,and the infiltration rate of the period 1 year after mining was mainly influenced by the soil bulk density of the period before mining.The results indicated that vegetation types had significant effects on soil bulk density,and that the tree-shrub-grass mode was better than one single plantation for water conversation and vegetation recovery in sandy land subjected to mining.

Diffusion of Chloride Ions in Soils:I.Influences of Soil Moisture, Bulk Density and Temperature

Diffusion coefficients of chloride ions in four soils of different texture with varying effective moisture content and varying bulk density from 1.1 to 1.6 g cm3 under three different temperatures were determined by the diffusion-cell method using 36Cl-labelled CaCl2 solution. The results showed that activation energy decreased with water content, which indicated that the threshold for diffusion was lower at a higher soil moisture rate. Therefore, the diffusion coefficient (D) of chloride ions in soil increased consistently with soil moisture. Although a near linear increase in the diffusion coefficient with increasing soil moisture or bulk density in all the soils was observed, the increase rate in different soils was not the same. The D value increased with temperature, and with temperature increased by 10℃ in the range from 5 "C to 45℃ theD valve increased by 10%～30%, averaging about 20%.

Spatial variability of soil bulk density and its controlling factors in an agricultural intensive area of Chengdu Plain,Southwest China

Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use management.In this study,we evaluated the spatial variability of soil bulk density in the 0–20,20–40,40–60 and 60–100 cm layers as well as its affecting factors in Southwest China’s agricultural intensive area.Results indicated the mean value of surface soil bulk density(0–20 cm)was 1.26 g cm^(–3),significantly lower than that of subsoil(20–100 cm).No statistical difference existed among the subsoil with a mean soil bulk density of 1.54 g cm^(–3).Spatially,soil bulk density played a similar spatial pattern in soil profile,whereas obvious differences were found in details.The nugget effects for soil bulk density in the 0–20 and 20–40 cm layers were 27.22 and27.02%while 12.06 and 3.46%in the 40–60 and 60–100 cm layers,respectively,gradually decreasing in the soil profile,indicating that the spatial variability of soil bulk density above 40 cm was affected by structural and random factors while dominated by structural factors under 40 cm.Soil organic matter was the controlling factor on the spatial variability of soil bulk density in each layer.Land use and elevation were another two dominated factor controlling the spatial variability of soil bulk density in the 0–20 and 40–60 cm layers,respectively.Soil genus was one of the dominated factors controlling the spatial variability of soil bulk below 40 cm.

Monitoring of Soil Bulk Density in Context with Its Small-Scale Spatial Heterogeneity

The main aim of soil monitoring system is to obtain the knowledge of the most current state and development of soil properties according to concrete threats to soil. To determine the significant changes of soil properties in time, it is important to know spatial variability of concrete soil parameter for concrete site. Only those time changes of the soil parameter are significant, which exceed its spatial variability at the site. The main aim of the study has been focused on the evaluation of small-scale site heterogeneity of equilibrium soil bulk density and the integration of impact of this heterogeneity in evaluation of degradation process of soil compaction in time. As site variation coefficients have considerably varied at standard sampling with five repetitions during monitoring period, one-time detail spatial variability mapping of soil bulk density was realized at 17 repetitions on five selected monitoring sites with different soil type, texture and use. This increase in the number of sampling points helped us to specify and stabilize the values of variation coefficients (between minimum and maximum by standard sampling) as well as the extent of confidence intervals. Standard deviations at the chosen monitoring sites moved from 0.039 to 0.118 g·cm-3 in topsoil and from 0.031 to 0.067 g·cm-3 in subsoil and expressed as variation coefficient 2.9% - 9.2% and 2.0% - 4.9%, respectively. The intervals of significant time changes of soil bulk density for the sites and depths were determined on the base of its site confidence interval (95%) and uncertainty rate of its measure methodology. The time changes of bulk density values between single year-to-year sampling were overlapped by this interval of significant changes to obtain significant bulk density changes in time. This method allowed us to distinguish significant time changes in soil bulk density from insignificant ones. The bulk density value changes on the monitoring sites were significant in the range of six to nine years within observed period 2002-2014 in both depths.

Comparing Two Methods for Measuring Soil Bulk Density and Moisture Content

Soil bulk density and moisture content are dynamic properties that vary with changes in soil and field conditions and have many agricultural, hydrological and environmental implications. The main objective of this study was to compare between a soil core sampling method (core) and the CPN MC-3 EliteTM nuclear gauge method (radiation) for measuring bulk density (ρB) and volumetric moisture content (θv) in a clay loam soil. Soil ρB and θv measurements were determined using the core and radiation methods at 0 - 10 and 10 - 20 cm soil depths. The mean values of soil ρB obtained using the core method (1.454, 1.492 g·cm−3) were greater than those obtained using the radiation method (1.343, 1.476 g·cm−3) at the 0 - 10 and 10 - 20 cm depths, respectively. Mean ρB and θv values averaged across both depths (referred to as the 0 - 20 cm depth) measured by the core method were 4.47% and 22.74% greater, respectively, than those obtained by the radiation method. The coefficients of variation (CV) of soil ρB values measured by the core method were lower than the CV values of those measured by the radiation method at both depths;however, the CV’s of ρB values for both methods were larger at the 0 - 10 cm depth than those measured at the 10 - 20 cm depth. Similarly, the CV values of soil θv values measured by the core method were lower than the CV values of those measured by the radiation method at both depths. There were significant differences between two methods in terms of ρB and θv, with the core method generating greater values than the radiation method at the 0 - 20 cm depth. These discrepancies between the two methods could have resulted from soil compaction and soil disturbance caused by the core and radiation techniques, respectively, as well as by other sources of error. Nevertheless, the core sampling method is considered the most common one for measuring ρB for many agricultural, hydrological and environmental studies in most soils.

不同灌溉水源对高原夏芹菜土壤理化性质及其产量、品质的影响

以芹菜品种文图拉为试材,研究引洮水及其引洮水和浅层地下水交替灌溉、浅层地下水3种不同灌溉水源对土壤容重、土壤温度及夏芹菜产量及品质的影响。结果表明,灌溉水质对耕层内(0~30 cm)土壤容重的影响较大,用浅层地下水灌溉后土壤容重增幅最大;在夏芹菜生育期内,土壤温度变化受灌溉水质和气温影响较大,其中引洮水灌溉后生育期土壤平均温度21.4℃,较地下水灌溉高0.7℃;在全生育期灌溉制度相同的条件下,因地下水含氮、磷等有机物较多,灌溉处理夏芹菜产量最高,达135870 kg·hm^(-2),比引洮水灌溉增产21005 kg·hm^(-2),但芹菜粗纤维含量高,食用品质降低。综上,使用矿化度低的引洮水灌溉芹菜,能使土壤保持较好的理化性质,提高芹菜发芽期土壤表层平均地温,有利于芹菜根系的呼吸和生长,易形成茎,能增加芹菜茎秆鲜质量的比例,达到80.79%。

基于机器学习的土壤机械压实应用研究

农业机械作业造成的土壤压实已成为制约农业可持续发展的重要因素,过度机械压实使土壤理化性质恶化,甚至成为降低作物产量的主要原因。已有的土壤机械压实研究多是基于简单的数学统计分析,且研究重点为试验方案的设计,无法挖掘数据内部关系,也无法进行土壤机械压实程度的预测。近几年,随着机器学习的不断发展,越来越多的学者开始将其引入农业领域及土壤机械压实的研究。为此,分析了机械压实对土壤理化性质及作物生长的影响,总结了土壤机械压实的表征属性和常用机器学习算法及评价标准,并归纳了近几年基于机器学习的土壤压实的研究成果,给出了相关应用研究的建议。

树种对土壤物理性质的影响——7种亚热带树种同质园试验

【目的】通过了解树种差异对土壤物理性质的影响,为亚热带人工林树种优化及土壤改良提供理论依据。【方法】试验以亚热带同质园7个阔叶树种,即大叶樟(Cinnamomum septentrionale)、桤木(Alnus cremastogyne)、油樟(Cinnamomum longepaniculatum)、天竺桂(Cinnamomum japonicum)、香樟(Cinnamomum camphora)、红椿(Toona ciliate)和香椿(Toona sinensis)为研究对象,在立地5 a后(2015-2020年)测定不同树种人工林和邻近撂荒地各土层(0~10、10~20和20~30 cm)土壤容重、总孔隙度、坚实度和抗剪强度的变化规律。【结果】①相较于撂荒地,树种显著影响0~30 cm土壤容重、0~10 cm和20~30 cm土壤坚实度和总孔隙度、20~30 cm土壤抗剪强度;②油樟、大叶樟、天竺桂和香樟4种樟属植物表层土壤容重整体高于其他树种,但土壤总孔隙度则相反;③土壤容重、土壤坚实度和土壤抗剪强度总体随土壤深度的增加而增大,变化范围分别为1.22~1.54 g/cm^(3)、143.9~335 N/cm^(3)和0.49~2.25 kg/cm^(2),土壤总孔隙度则呈现相反的变化趋势,变化范围为47.26%~52.55%;④土层深度显著影响土壤容重、总孔隙度、坚实度和抗剪强度,树种和土壤层次的交互作用显著影响土壤总孔隙度。【结论】树种可能通过改变凋落物输入和根系活动影响土壤理化性质,种植樟属植物可改善土壤物理特性。

稻蟹共作对土壤理化性质及土壤酶活性的影响

为探究稻蟹共作对土壤理化性质及土壤酶活性的影响,采用水泥池模拟稻田环境的方法,对比研究了稻蟹共作与水稻单作模式7个土壤理化指标和4个土壤酶活性的差异。结果表明:与稻田单作相比,稻蟹共作对土壤容重、土壤含水率和土壤还原性物质总量均有显著影响(P<0.05);稻蟹组的总有机碳略高于稻田组,但总氮略低于稻田组;稻蟹组与稻田组的Eh存在极显著差异,两组之间差异达20.95%;稻蟹组和稻田组土壤粒径机械组成均为粉粒>粘粒>粗细砂粒,粉粒占比均超过80%,且两组之间存在显著差异(P<0.05);随着土壤深度的增加,稻田组的四种酶活性均呈显著下降趋势;稻蟹组的脲酶、纤维素酶和蔗糖酶活性变化与稻田组一致,呈显著下降趋势,但其酸性磷酸酶没有变化。可见,稻蟹共作系统由于河蟹的引入,降低了土壤容重,提高了土壤含水率,改良了土壤,其水稻根系分布较多的10~15 cm底层土壤显示了较强的土壤酶活性,促进了水稻对稻蟹共作系统中碳、氮等元素的高效利用。因此,稻蟹共作系统既有利于水稻生长,又有利于河蟹养殖,可以作为一种生态种养模式在江苏地区推广应用。

自制鸡粪有机肥及其套餐式施肥技术对桃产量及品质的影响

以十年生桃园为实验材料,以施用化学肥料为对照,以一般的农家肥(处理Ⅰ)、和市场上出售的成品有机肥(处理Ⅱ)为对比,研究了自制鸡粪有机肥(处理Ⅲ)及其套餐式施肥技术对桃产量及品质的影响。结果显示在N、P、K供给量一致的情况下,自制发酵鸡粪可以明显的改善桃园土壤结构、提高鲜桃品质和质量,其产量分别比CK、处理I提高了8.98%、4.03%,效益分别比CK、处理Ⅰ、处理Ⅲ提高了36.27%、30.72%和21.51%;处理Ⅱ与处理Ⅲ两组的鲜桃果实个大且果面光滑,着色好,含糖量高,商品性好,可以证明自制发酵鸡粪与市场上出售的成品有机肥相比效果无显著性差异,但成本大大降低。

高寒矿区环境材料混施下土壤改良及工程应用研究

为了解决高寒矿区土地复垦中表层土壤结构差、水土流失和土壤肥力低下等问题,以青海威斯特铜矿为例,通过土壤培养模拟正交设计试验,研究了混施羊板粪(A)、TG改良剂(B)、保水剂(C)3种材料对土壤改良的效果,并筛选出一种效果最佳的混合比例。正交极差结果表明:羊板粪对土壤有机质、土壤密度、孔隙度和全盐含量的影响较强,TG改良剂对pH的影响较强,保水剂对田间持水量的影响较强。综合极差分析和主成分分析结果得,处理1(A含量6 g/kg,B含量1.85 g/kg,C含量0.06 g/kg)为改良土壤理化性能最优组合。通过冗余分析得出,羊板粪和TG改良剂对土壤理化性质的差异性解释最好。有机质、土壤田间持水量和孔隙度与环境材料的相关性较强。有机质与羊板粪呈正相关,孔隙度和田间持水量与保水剂、TG改良剂呈正相关。pH、全盐含量和土壤密度与环境材料的相关性较小。孔隙度和田间持水量正相关性强,二者与有机质呈负相关。综合考虑,土壤有机质最优组合A3B3C2和土壤其他理化性能最优组合A1B1C1,通过中值法得到高寒矿区土壤基质恢复最优配方结果为A2B2C1.5,即A含量12 g/kg,B含量3.7 g/kg,C含量0.09 g/kg为最优配比。通过工程应用,总结出以“边坡修整、挂椰网/铁丝网、挂生态棒、设置排水沟、客土筛分、客土喷播、铺设保水毯、养护管理及监测”为主的技术应用流程,将试验配方研究和工程应用进行了结合。3种环境材料工程应用结果表明,土壤理化性质和生物量也得到明显改善。此研究为解决青藏高海拔矿区土壤肥力和结构的恢复提供参考,对水土保持产生重要意义。

Effect of Different Land Use Patterns on Physical Properties of Soil Water in Yellow River Wetland in Shaanxi Province

[Objective] This study was to reveal the effect of different land use patterns on physical characteristics of soil water in the Yellow River wetland in Shaanxi Province.[Method]Taking Yellow River wetland in Shaanxi Province as experimental plot,we compared the physical properties of the soil water under different land use patterns and studied the physical properties and the change law of soil water during the wetland degeneration process.[Result]Under different land use patterns,soil bulk density rose with the increase of soil depth.During the degeneration process of from river wetland to reclaimed wetland（paddy field）,finally to abandoned land owing to salinization,the mean soil bulk density reduced correspondingly from 1.474 to 1.522 g/cm3,finally to 1.593 g/cm3 when abandoned.Accompanying wetland degeneration,soil became compact increasingly,and the indicators of soil porosity（total porosity,capillary porosity,non-capillary porosity）were also reduced with the change of land use patterns,in which,capillary porosity and total porosity reached the extremely significant level with the change of land use patterns,and non-capillary porosity reached significant level.The changes of soil porosity condition accelerated the deterioration of wetland.Under different land use patterns,the maximum soil moisture capacity,capillary moisture capacity and minimum moisture capacity all showed a similar change law.Compared with wetland,the maximum soil moisture capacity of reclaimed land（paddy field）and salinized land respectively decreased by 5.7% and 22.3%,capillary moisture capacity by 0.2% and 19.4%,minimum moisture capacity by 2.7% and 15.9%.Of the three land use patterns,wetland displayed both higher water holding capacity and water drainage capacity over reclaimed land（paddy field）and salinized land.By comparison with wetland,the reclaimed land（paddy field）and salinized land respectively decreased by 12.4% and 15.2% in total water holding capacity,and by 2.7% and 15.9% in total water drainage capacity.[Conclusion]To conserve the water resource in Yellow River wetland,regulate the hydrological cycle and enhance drought and water logging resistances,it should be noted that reasonable countermeasures be taken to exploit the state-owned forest land and paddy field around the wetland and the related resources.

施加生物炭对黑土区坡耕地土壤主要理化指标的动态影响

采用田间原位监测试验方法,设计CK(不施加生物炭)和SW(施加生物炭30 t·hm^(-2))2个处理,研究施加生物炭当年(5—10月)对东北黑土区坡耕地土壤容重、土壤质量含水率、土壤pH值、电导率、有机质含量和阳离子交换量等主要理化指标的影响。结果表明,施加生物炭当年土壤容重降低,其中,6—10月垄丘土壤容重降低6.42%~11.21%,且随时间延长,其降幅减小。施加生物炭当年6—8月的土壤质量含水率降低,且垄丘的降低幅度小于垄沟,随坡位由上到下,土壤质量含水率的降幅逐渐减小;而9—10月的土壤质量含水率增加,且垄丘的增加幅度大于垄沟,随坡位由上到下,土壤质量含水率的增加幅度逐渐增大。此外,施加生物炭能够增加土壤pH值、有机质含量,减小电导率。综上,施加生物炭当年即可改变土壤主要理化指标,提升土壤质量。

不同耕翻深度对土壤养分及水稻产量的影响

[目的]了解不同耕翻深度对引黄灌区农田土壤蓄水保墒、养分及作物产量的影响,探寻能充分营造水、肥、气等水稻良好生长环境的合理耕翻深度,以期为引黄灌区水稻合理耕层构建及作物高产栽培提供理论参考。[方法]采用完全随机设计,设置3个耕翻深度处理,分别为耕翻22~25 cm、耕翻30~32 cm、耕翻38~42 cm,研究不同耕翻深度对土壤容重、含水率、土壤养分、水稻产量的影响。[结果]在不同耕翻深度下土壤含水率整体表现在耕翻30~32 cm处理下较高;土壤容重在0~10 cm土层下以耕翻22~25 cm处理较低,在20~40 cm土层下以耕翻30~32、38~42 cm处理较低,且耕翻30~32 cm处理显著低于38~42 cm处理;有机质、有效磷和速效钾含量在0~20 cm土层以耕翻30~32 cm处理较高,在20~40 cm土层以耕翻38~42 cm处理较高;水稻产量耕翻30~32 cm处理显著高于耕翻22~25和38~42 cm处理;通过主成分综合评价得到耕翻30~32 cm处理>耕翻38~42 cm>耕翻22~25 cm。[结论]不同耕翻深度可影响耕层土壤结构及土壤养分,进而影响土壤的蓄水保温效应,促进作物生长和产量提高,在该地土壤条件下耕翻30~32 cm处理对土壤的综合改善效果最佳,水稻产量较高。

土壤类型和容重对离心机法测定土壤水分特征曲线的影响

本研究以杨凌塿土和嫩江黑土为研究对象,分别设置了4个土壤容重处理(1.0、1.1、1.2、1.3 g/cm^(3)),利用离心机法测定土壤失水过程,以压力膜仪法为标准,对比不同吸力下的含水量实测值和van Genuchten模型参数的差异。结果表明,随着土壤容重的增加,离心机法测定土壤水分特征曲线准确度逐渐增加,获取黑土和塿土的van Genuchten模型参数α的准确度增幅分别为38.46%~83.08%和56.38%~95.75%。离心机法测定土壤水分特征曲线的准确度在不同吸力段表现不同,近饱和段(0~10 kPa)离心机法测定值偏低,而高吸力段(10~1500 kPa)测定值偏高,且高吸力段离心机法测定准确度较低,与压力膜仪法测定值具有极显著差异(P<0.01)。综上所述,为了提高离心机法测定土壤水分特征曲线的准确度,优先考虑应用于大容重和高有机质含量的土壤。

高寒矿区蛇纹石渣土配制及其改良种植基质的试验——以青海威斯特铜矿为例

针对青藏高原高寒矿区“客土”资源缺乏、土壤结构质量差和植被建造困难等问题,研究蛇纹石渣土与当地原土配制和改良,为植被建造提供种植基质。以青海威斯特铜矿为例,通过土壤模拟、盆栽种植和田间小区试验方法,对矿区蛇纹石渣土与当地原土进行种植基质配制,并通过改良试验确定种植基质的改良方案。蛇纹石渣土与原土不同比例配制极大影响基质的理化性能。蛇纹石渣土与原土配制比例6∶4时,种植基质土壤密度、pH和土壤电导率分别与纯蛇纹石渣土对照(CK)降低2.20%、7.95%和19.88%,土壤毛管孔隙度、田间持水量,以及有效磷、速效钾、全氮和水解性氮的质量分数分别显著增加15.12%、7.02%、75.23%、328.88%、117.65%和32.38%,达到绿化基质基本要求;盆栽种植表明,蛇纹石渣土与原土配制比例6∶4时,单种植披碱草和混种6种草籽等牧草的出苗数较对照CK提高10.34%和25%,披碱草株高、地上生物量、地下生物量分别较对照CK提高7.25%、87.00%和246.95%;田间小区种植试验表明,蛇纹石渣土与原土配制比例为6∶4且添加TG改良剂1 kg/m^(2)、KM 3005保水剂12 g/m^(2)和羊板粪3.12 kg/m^(2)时,羊板粪和TG改良剂梯度试验出苗株高和生物量分别较对照提高38.30%和200.43%、21.43%和358.02%,并得到工程示范应用。蛇纹石渣土与原土按照6∶4配制并通过TG改良剂、保水剂和羊板粪改良后,能达到矿区生态修复的植物种植的基质要求,试验结果对促进青海高寒矿区的生态修复具有重要参考。

戈壁石土壤葡萄埋藤装置设计与试验

针对含戈壁石土壤机械化葡萄埋藤越冬作业难度大、能耗高、理论研究少等难题,考虑含戈壁石土壤的葡萄埋藤农艺要求,设计了一种可在戈壁石土壤中葡萄埋藤的铰臂式锯齿形刀结构和葡萄埋藤机装置,并根据葡萄埋藤农艺要求,对埋藤装备关键部件进行参数设计和计算。考虑土壤的挖掘、摩擦、移动和抛出等影响因素建立了功耗算法,特点是土壤容重越大所需功耗也越大。通过确定含戈壁石土壤埋藤机所匹配的履带式拖拉机总功率,在戈壁石含率分别为19.73%和32.24%的两种实验区进行了埋藤覆土试验。在这两个实验区,埋藤覆土平均厚度的最大值分别为0.19m和0.21m,最小值分别为0.1m和0.097m,埋藤覆土宽度均为1.2m,满足吐鲁番地区含戈壁石土壤的葡萄埋藤农艺要求,可有效降低葡萄种植成本、减轻劳动强度、提高综合经济效益。

The impact of tourism on soils in Zhangjiajie World Geopark

The soil hardness, soil water content and soil bulk density along the trails of six scenic spots in the Zhangjiajie World Geopark were measured and analyzed, and the integrated effects of tourism trampling on soils were evaluated for each scenic spots by calculating its soil impact indexes （SII） in the park. The results indicated that visitors＇ activities caused a serious influence on the soil in the park, especially in the two most used scenic spots-- Yellowstone Village and Gold Whip Stream. The impact of tourism on soil mainly occurred within 3 m along the trails. The impact shapes are classified into six type as single-sided node type, double-sided node type, cross node type, single-sided linkage type, double-sided linkage type and short-cut linkage type. Of six types of impact shapes, the single-sided node type and double-sided type were dominant. The average water contents of soil for six scenic spots at sample areas of 1 m, 2 m and 3 m from trial is 36.6%, 24.5% and 2.2% lower than that of the control area, respectively. The average soil hardness for six scenic spots at 1m, 2 m, and 3m from the trails tramped increased 167.9%, and 122.2%, and 15.8%, respectively, compared with the control area. Soil bulk density increased 26.5% at 1 m and 20.9% at 2 m from the trails. The main countermeasures for reducing the range and extent of tourism impact on soil are discussed.