Drip fertigation and plant hedgerows significantly reduce nitrogen and phosphorus losses and maintain high fruit yields in intensive orchards

A field experiment was carried out to evaluate the effects of drip fertigation combined with plant hedgerows on nitrogen and phosphorus runoff losses in intensive pear orchards in the Tai Lake Basin.Nitrogen and phosphorus runoff over a whole year were measured by using successional runoff water collection devices.The four experimental treatments were conventional fertilization(CK),drip fertigation(DF),conventional fertilization combined with plant hedgerows(C+H),and drip fertigation combined with plant hedgerows(D+H).The results from one year of continuous monitoring showed a significant positive correlation between precipitation and surface runoff discharge.Surface runoff discharge under the treatments without plant hedgerows totaled 15.86%of precipitation,while surface runoff discharge under the treatments with plant hedgerows totaled 12.82%of precipitation.Plant hedgerows reduced the number of runoff events and the amount of surface runoff.Precipitation is the main driving force for the loss of nitrogen and phosphorus in surface runoff,and fertilization is an important factor affecting the losses of nitrogen and phosphorus.In CK,approximately 7.36%of nitrogen and 2.63%of phosphorus from fertilization entered the surface water through runoff.Drip fertigation reduced the accumulation of nitrogen and phosphorus in the surface soil and lowered the runoff loss concentrations of total nitrogen(TN)and total phosphorus(TP).Drip fertigation combined with plant hedgerows significantly reduced the overall TN and TP losses by 45.38 and 36.81%,respectively,in comparison to the CK totals.Drip fertigation increased the vertical migration depth of nitrogen and phosphorus nutrients and reduced the accumulation of nitrogen and phosphorus in the surface soil,which increased the pear yield.The promotion of drip fertigation combined with plant hedgerows will greatly reduce the losses of nitrogen and phosphorus to runoff and maintain the high fruit yields in the intensive orchards of the Tai Lake Basin.

Avian diversity in hedgerows,preference to hedgerow types and their conservation at Angacha (Kembatta),central Ethiopia

The present study aimed to investigate avian diversity in hedgerows at Angacha, in the Kembatta zone, Ethiopia. Transect and point-count methods were deployed to determine avian diversity, species richness, similarity and preferences across five sub study sites. Diversity and preferences of birds to hedgerow types varied in relation to their vegetation composition and structure. Five endemic species, i.e., Rüppel’s Black Chat (Cossyfa semirufa), the White-cheeked Turaco (Tauraco leucotis), the Banded Barbet (Lybius undatus), the Abyssinian Oriole (Oriolus monacha) and the Wattled Ibis (Bostrychia carucullatta) were recorded in the thick hedgerow type. Thickness, height and width of hedgerows affected the diversity, distribution and habitat preference of birds. Thick hedgerow types showed the highest avian species diversity, richness and similarity. There was a high correlation between the hedgerow diversity and its bird diversity, which was directly associated with habitat quality. Bird species diversity and preference for hedgerow types require important conservation and management priorities.

Nitrogen Mineralization of Prunings of Six N_2-Fixing Hedgerow Species in a Dry Valley of the Jinsha River

A litterbag experiment of 12 weeks was conducted to study nitrogenmineralization process of prunings of six nitrogen-fixing hedgerowspecies in a dry valley of the Jinsha River. Prunigns wereincorporated into soil or used as mulch. The results indicated thatpruning N of the six hedgerow species was mineralized fast in thefirst week and then decreased slowly in the rest of the study period.When prunings were incorporated into soil, the amount of nitrogenmineralized by the end of the first week accounted for 69.9/100,58.2/100, 54.5/100, 43.0/100, 29.6/100 and 20.6/100 of the total N inprungins of Desmodium rensonii, Tephrosia candida, Leucaenaleucoephala, Albizia yunnanensis, Acacia dealbata, and Acaciamearnsii, respectively.

Effects of Contour Hedgerow Intercropping on Nutrient Losses from the Sloping Farmland in the Three Gorges Area,China

Eutrophication is recognized as one of the major environmental problems in the Three Gorges Reservoir.Contour hedgerows have been used as a major soil and water conservation measure in this area.Accordingly,a two-year study was conducted to investigate the effects of contour hedgerow intercropping on nutrient loss from sloping farmland in this area.Four treatments were applied:(1) Maize + Soybean,(2) Maize,(3) Maize + Alfalfa,and(4) Maize + Hemerocallis citrina Baroni.Results indicated that nutrient loss in the control treatment(Maize) was serious,especially the average loss flux of total nitrogen(2245.8 mg) and total phosphate(2434.2 mg) in a typical rainfall event.However,the nutrient losses by runoff in the other three treatments with contour hedgerow intercropping showed significant reduction.Compared with the control treatment,the total nitrogen loss in the Alfalfa and Hemerocallis citrina Baroni decreased by 80.9% and 85.0%,respectively,and the total phosphorus loss in the two treatments decreased by 91.2% and 92.5%,respectively.Therefore,it is concluded that nutrient losses could be reduced by using contour hedgerows in the Three Gorges Region.Reducing runoff volume and sediment loss was the main mechanisms of contour hedgerow intercropping to reduce nutrient loss.

Impact of Different Contour Hedgerows on Runoff,Nutrient and Soil on Sloping Farmland in Danjiangkou Reservoir Region of China

Soil and water loss has been a major environmental problem in the Danjiangkou Reservoir Region.A study of 14°sloping farmland was performed on impact of different contour hedgerows on runoff,losses of soil and nutrients during 2008 and 2011,with five treatments and three replications.The winter wheat and summer maize were used as the test crops.Treatments consisted of four hedgerows:Amorpha(Amorpha fruticosa L.),Honeysuckle(Lonicera japonica Thunb.),Day-lily flower(Hemerocallis citrina Baroni.),and Sabaigrass(Eulaliopsis binata),and a control without hedgerow.Result showed that the runoff under the control treatment was much higher than that of hedgerows.Amorpha could reduce the runoff by 35.2%compared with the control.Soil losses in four hedgerows showed significant reduction in four years(e.g.,Amorpha:78.3%;Honeysuckle:77.1%).Nutrient losses in winter were much higher than that in summer,especially total nitrogen,total phosphorus and total potassium,even though there was an abundant precipitation in summer.Hedgerows greatly affected the soil and nutrient losses on slopping farmland compared with the control treatment,especially Amorpha treatment.The present study found that the Amorpha could be used as the hedgerow species for reducing soil and water loss in the Danjiangkou Reservoir Region.

Occurrence Regularity and Ecological Control Technology of Diseases of Hedgerow Commonly Used in Greening in Five Cities of Southern Jiangsu

The disease types, symptom characteristics, pathogenesis and ecological control technology of hedgerow commonly used in landscape greening in Nanjing, Zhenjiang, Changzhou, Wuxi and Suzhou were systematically studied. The results showed that there were 10 kinds of common diseases of flowers and shrubs in landscape greening in five cities of southern Jiangsu. Among them, 8 were caused by deuteromycotina and 2 were caused by subphylum basidiomycetes. It was pointed out that the disease regularity was directly related to the pathogenic bacteria, temperature and humidity, microclimate and hedgerow growth. For the first time, the ecological control method of hedgerow disease which focused on ecological health maintenance was put forward.

Hedgerow Intercropping Maize or CowpealSenna for Drymatter Production in Semi-Arid Eastern Kenya

In a long term study photosynthetically active radiation was monitored for three rainy seasons to measure the effects of hedgerow intercropping in rotation with maize and cowpea in a senna/siamea and panicum/grass strip on biomass yield and light use efficiency. Maize/cowpea intercropped with senna siamea or grass stripped were compared with sole maize and cowpea. A ceptometer was applied to measure PAR interception by sole maize or cowpea or crop/tree and grass/crop interfaces and separation of PAR used by each plant or tree/grass component. Hedgerow intercropping increased PAR interception and biomass formation. C4 plants had higher LUE than C3 plants while combining C4 and C3 in the agroforestry system lowered LUE. The tree/crop interfaces increased PAR interception than at 1 m and 2 m away from the hedgerow. The row of maize or cowpea at lm intercepted more PAR than the row at 2 m from hedgerow while the cowpea row next to the hedgerow was depressed compared to the rows in the middle rows which had higher yields. The maize or cowpea row next to the grass strip was more stressed than the rows in the middle of the alley.

Enhanced Species Diversity Unlocked by Habitat Conservation in Agricultural Landscapes: New Perspectives on Ecological Weed Management and Sustainable Intensification—Species Diversity and Habitat Conservation

The impulse to remain profitable by increasing agricultural production levels in view of the greater demand for food, provided impetus to production intensification. The aim of this review is to summarise current literature, reporting specifically on the impact of production intensification on habitats and yield constraints caused by weeds. Secondly, in alleviating these effects over the short term, ecological measures that enhance species diversity in conserved habitats and promote semi-natural habitats in the agricultural landscape, are discussed. In large-scale intensive agriculture, weed control is predominantly rooted in agrochemical applications in the form of herbicides. Long lasting intensive agricultural practices show discord both with the promotion of the biodiversity of microbes belowground and aboveground and with organisms involved in the breaking down of plant material. The presence of native species in the surroundings, in combination with hedgerows and field margins, with a comparatively intricate and balanced variety of plants in a sheltered environment, are essential for settlement of benign insects, particularly in the face of intensive agricultural production. The promising tactic of advantageous seed predators enables decreased herbicide applications. Crop mosaics arranged to advance compatibility at the landscape scale are important to bolster pollination services and insect management, while ecological variety in the surroundings acts as a safety net for habitat diversity. Weed control in combination with different tactics of vegetation use, comprising cover cropping, hedgerows and field margins, sets up safe havens in the landscape, and improves the diffusion of complementary life forms. Field margins perform a meaningful natural function as point of provision for forage, safe havens and distribution passageways for pollinators and insect predators. Production practices that promote more heterogeneity and combine high density semi-natural safe havens and habitat conservation in agro ecosystems are beneficial to species diversity across trophic levels and contribute to agricultural production stability and food safety.

太行山坡地植物篱种植对土壤水肥的短期影响

为探讨生物措施对人工林坡地土壤环境改善效果,在太行山东麓典型坡地布设枸杞、欧李、连翘、金银花、薄荷5种植物篱,并以平行位置的空白裸地为对照,分析不同植物篱及篱带位置对表层土壤水肥的影响。结果表明:1)与土壤水分相关指标中,不同植物篱带上、带中位置土壤自然含水量较空白对照提高了14.55%~62.69%,土壤总孔隙度基本高于空白对照,且不同植物篱间差异显著(P<0.05),植物篱土壤容重明显降低,且其带上、带中位置土壤黏粒含量较空白对照降低了1.25%~18.56%。2)与土壤肥力相关指标中,不同植物篱土壤有机碳含量较空白对照提高了8.93%~64.00%,土壤碳氮比明显高于空白对照,土壤pH、电导率、全氮含量多低于空白对照,且不同植物篱间差异显著(P<0.05)。3)各植物篱土壤水肥指标之间相关性显著,土壤全氮含量与电导率、自然含水量之间分别呈显著正相关和负相关(P<0.05);土壤有机碳含量与粉粒含量之间呈显著正相关(P<0.05),与总孔隙度、砂粒含量之间呈显著负相关(P<0.05)。4)不同植物篱对土壤水肥影响能力综合得分:金银花(1.970)>薄荷(1.677)>欧李(1.670)>枸杞(1.655)>连翘(1.643)>空白对照(1.527)。5种植物篱短期内均有保持土壤水分和调节土壤肥力能力,其中金银花土壤水肥调节效果最好,可用于修复水土流失较严重的太行山坡地。

川中丘陵区紫色土坡耕地植物篱措施对土壤抗蚀性的影响

川中丘陵区紫色土坡耕地水土流失严重,影响农作物增产增收。水土保持植物篱措施是提高土壤的抗侵蚀能力的有效生态手段。以往土壤抗蚀性的研究多集中于黄土高原,较少涉及植物篱作用下紫色土坡耕地抗蚀机理方面的研究。本文以新银合欢(Leucaena leucocephala)和香根草(Vetiveria zizanioides)为研究对象,基于试验站坡耕地小区定位观测的基础数据,结合土壤采样和实验分析,利用主成分分析法对种植不同植物篱的坡耕地土壤抗蚀性进行了综合评价。结果表明:(1)在分析11项指标后,2项主成分指标对解释土壤抗蚀性贡献率达到82.7%,其中水稳性团聚体被认定为关键指标。(2)植物篱显著提高了表层土的抗蚀性。与无植物篱的样区为对照,10°坡耕地上香根草和新银合欢植物篱小区的土壤抗蚀性综合指数(SERI)分别比对照区高2.048和0.853,15°坡耕地上香根草植物篱的SERI比对照区高1.321;且植物篱下侧的土壤抗蚀性高于植物篱上侧,在10°和15°香根草植物篱小区,植物篱下侧抗蚀性指数分别达到上侧的2.0倍、1.5倍,而10°新银合欢植物篱小区的下侧抗蚀性综合指数达到上侧的1.1倍。(3)相较于新银合欢植物篱小区,香根草植物篱小区土壤表现出了更高的抗蚀性,且两种植物篱小区下侧土壤抗蚀性均优于上侧,选择密植草本植物篱并重点防治植物篱上侧土壤可有效减少坡耕地水土流失。研究成果可为川中丘陵区水土流失治理及农业增产提供科学依据。

太行山坡地4种植物篱及不同篱带位置土壤抗蚀性研究

研究太行山坡地不同植物篱及篱带前、篱带内、篱带后土壤抗蚀性的变化特征,为该区水土保持和退化坡地生态恢复工作提供科学支撑。以枸杞(Lycium chinense)、欧李(Cerasus humilis)、薄荷(Mentha canadensis)、连翘(Forsythia suspense)4种植物篱及空白裸地为研究对象,选择9个土壤抗蚀性指标,运用主成分分析方法进行土壤抗蚀性评价。结果表明:1)植物篱样地的土壤容重、可蚀性K值普遍低于裸地,孔隙度、持水量、养分含量、土壤颗粒分形维数及水稳性指数普遍高于裸地,且各指标在植物篱带前、带内、带后具有显著差异性。2)主成分分析结果表明:土壤容重、毛管孔隙度、饱和持水量、有机质是评价该研究区土壤抗蚀性的最佳指标,植物篱样地的土壤抗蚀性优于裸地,整体表现为枸杞>连翘>欧李>薄荷>裸地,且植物篱带内土壤抗蚀性强于带前、带后。3)土壤抗蚀指数与毛管孔隙度、全氮、有机质、土壤颗粒分形维数存在显著正相关关系(p<0.05),与可蚀性K值存在显著负相关关系(p<0.05)。综上,植物篱种植可一定程度上提高土壤抗蚀性,且4种植物篱中,枸杞的效果较好。建议该区域可优先选用枸杞作为生态修复物种,增强坡地水土保持能力和抗蚀性。

Tunnel-convective air-assisted spraying technology for improving droplet deposition on hedgerow vines

Given the impermeability,larger dosage,and higher drift of pesticides used in modern hedgerow vine canopies,a novel tunnel-convective air-assisted spraying technology was proposed.Mechanized spraying equipment with high penetration and low drift was developed.The air-assisted system of this equipment was centrosymmetric,and the fan type was cross-flow.The fan outlet width was 138 mm and the air duct’s main body followed a logarithmic spiral profile,based on parallel flow theory.The external diameter of the impeller was 157 mm,which was fixed into a barrel structure by 23 strong forward-curved blades,each being 1 mm thick.The central angle of the blades was 108°,and the ratio of the internal and external diameters was 0.81.The impeller and air duct served as guides to circulate and reciprocate airflow around the crown,forming a tunnel-convective air-assisted to the vine.Using MATLAB interpolation,the airflow trajectory of the air convection circulation in the door-shaped cover was obtained.The velocity field distribution test showed that,in the case of a canopy,there were tunnel-convective circulating airflows with high velocity on both sides and uniform velocity in the middle of the canopy.Due to the tunnel-convective air-assisted spraying technology,the vertical distribution uniformity of spray deposition has been significantly improved,spray penetration has been enhanced,penetrability has been effectively improved,and droplets on the ground and in the air have been significantly reduced.The results of this study can assist in providing further optimization and improvement of plant protection machinery.The new tunnel-convective air-assisted spraying technology may be a more favorable choice for future spray applications and the environment.

坡地植物篱生态系统服务研究进展

坡地植物篱因其成本低、生态功能显著,已成为一项重要的坡地改良生物工程技术。梳理坡地植物篱技术相关研究成果,从生态系统服务新视角,阐述其概念与分类、品种选择与空间结构的技术要点,探讨坡地植物篱所具有的支持服务、调节服务、供给服务等,分析当前相关研究存在的问题,提出未来应加强坡地植物篱生态系统服务的理论基础与评估方法体系研究,探究坡地植物篱提供生态系统服务的微观机理,完善其选种、空间配置和管理等综合技术体系,逐步加大试种范围和推广力度。

太行山坡地不同植物篱对表层土壤水盐分布影响研究

[目的]探究不同植物篱对太行山坡地表层土壤水盐分布影响,为太行山坡地布设最优植物篱和减少水土流失提供理论与实践依据。[方法]以太行山坡度13°、海拔152 m正南坡地的薄荷、白芍、泽兰、艾草、锦灯笼、鱼腥草植物篱小区为研究对象,以空白裸地小区为对照,采集各小区植物和带上、带中、带下0—20 cm土壤,比较分析植物生理特征和土壤水盐特征差异,并采用主成分分析、聚类分析对植物篱影响土壤水盐分布能力进行综合评价。[结果](1)植物篱生理特征存在差异。薄荷、白芍地上、地下、总生物量较高,锦灯笼、鱼腥草则较低;白芍根冠比最高(p<0.05);鱼腥草、锦灯笼植物含水率较高,白芍则最低。(2)植物篱影响坡地土壤水盐分。与空白裸地相比,植物篱带中、带下平均土壤容重降低了9.23%,7.22%;植物篱带中平均自然含水量、饱和持水量、毛管持水量、田间持水量分别增加了8.10%,14.98%,21.49%,19.78%;植物篱带下平均电导率则降低了9.97%。(3)植物篱类型与篱带位置对土壤水盐分布存在交叉影响,其中植物篱类型显著影响自然含水量、饱和持水量、毛管持水量、田间持水量、pH和电导率(p<0.05),篱带位置显著影响电导率(p<0.05),植物类型×篱带位置显著影响自然含水量和电导率(p<0.05)。(4)植物篱生理特征与土壤水盐相关性显著,其地下生物量、根冠比、植物含水率与土壤水盐指标之间多呈显著或极显著相关(p<0.05,p<0.01)。(5)各植物篱对土壤水盐分布影响能力综合排序为:白芍>泽兰>锦灯笼>鱼腥草>薄荷>艾草。[结论]植物篱显著影响坡地表层土壤水盐分布,白芍植物篱对表土水盐分布影响能力最强,艾草植物篱则最弱,因此防治坡地水盐流失可优选白芍植物篱,若采取艾草植物篱则宜采取混交种植模式并合理布局。

香根草植物篱对三峡库区坡耕地侵蚀分布的影响

为探究植物篱对坡耕地侵蚀分布的影响,设置1个坡度(15°)、3个降雨强度(60,90,120 mm/h)和3种坡面条件(裸坡对照CK、植物篱P和仅有植物篱根系R),采用稀土元素氧化物将坡面分成5段(自上而下),开展室内人工模拟降雨试验。结果表明:随着降雨强度的增加,各坡面条件示踪坡段的侵蚀速率和侵蚀量均有所增加,整体上均表现为CK>R>P的趋势,植物篱可以显著降低坡面各部位的侵蚀速率及其侵蚀量,且使得侵蚀产沙主要集中在坡中部的Ce、La和Yb 3个示踪区。与CK坡面条件相比,R与P坡面条件下Sm和Ce示踪坡段对总侵蚀量的平均贡献率分别减少77.15%,90.38%和30.01%,28.35%,而Yb、La和Eu示踪坡段对总侵蚀量的平均贡献率分别增加54.34%,35.39%和12.39%,40.58%以及101.45%,91.31%。研究结果表明,植物篱造成坡面下部侵蚀贡献减小而中上部侵蚀贡献增加,坡面侵蚀部位整体上移,对坡地侵蚀的空间分布有显著影响。

植物篱对紫色土坡面侵蚀泥沙粒径分布特征的影响

为探究植物篱对紫色土坡面侵蚀泥沙粒径分布特征的影响,该研究以三峡库区紫色土为研究对象,在3种坡面条件下(裸坡对照组CK、植物篱P和仅地下根系R)以不同降雨强度(60、90 mm/h)进行人工模拟降雨试验。结果表明:与CK相比,R坡面条件下侵蚀泥沙中黏粒和粉粒含量减少了0.25%~5.48%,而P坡面条件侵蚀泥沙中砂粒含量减少了30.75%~47.28%。CK坡面条件下,泥沙分选现象主要出现在降雨前期,R坡面条件只影响降雨初期的泥沙分选,而P坡面条件对降雨全程均具有分选拦截砂粒的作用,但分选拦截效果随降雨时间的增加而渐趋稳定。R坡面条件下更多团聚体被雨滴击打破碎而分散为单粒,而P坡面条件则使更多细颗粒聚集形成团聚体,但松散的团聚体在降雨中后期倾向于分散为单粒。该研究结果可为深入理解植物篱对紫色土坡面侵蚀泥沙分选的影响,并为区域土壤侵蚀模型构建和水土资源高效利用提供科学依据和数据支持。

密云水库库区不同植物篱模式下的氮磷阻控效应

筛选拦截效果最佳、经济效益最佳的植物篱模式,为密云水库水源保护区控制坡耕地氮磷流失提供技术参考。设置“桔梗+狗牙根”“丹参+狗牙根”“桑树+野牛草”“黄芩+野牛草”4种不同的植物篱模式,监测2020年天然降水条件下的地表径流、泥沙以及养分情况,分析不同植物篱模式下径流小区的产流和产沙情况,探讨不同植物篱对坡耕地地表径流、泥沙和养分的拦截效率及其影响因素。结果表明:4种植物篱种植模式都能够起到截流减沙,减轻水环境富营养化的作用,从而避免对下游水体的污染。其中“桑树+野牛草”植物篱效果最为显著,大雨雨强下可以减流57.96%,减沙96.64%,暴雨雨强下可以减流64.63%,减沙97.17%;对氮的相对拦截量为93.14 mg,相对拦截率约88.27%;对磷的相对拦截量为25.17 mg,相对拦截率约80.72%,能有效减少地表径流中的氮、磷含量。在考虑经济效益、社会效益和生态效益下,开展植物篱防控面源污染工作中,最佳的物种选择为“桑树+野牛草”,其次为“黄芩+野牛草”。野牛草在防控水土流失与面源污染方面效果十分显著,可以作为水土保持的先锋植物推广。

植物篱防蚀措施对三峡库区坡耕地微地形的影响

本文对位于三峡库区陡坡地4种管理模式长期试验径流小区坡面地形相关参数进行了观测、分析。结果显示,与对照小麦–花生种植模式相比,采用套种紫花苜蓿植物篱、香椿植物篱能够极著降低水土流失,坡面地形沿篱基梯级化显著。而黑麦草–籽粒苋替代模式对水土流失控制效果不稳定,且坡面地形与对照无差异。小麦–花生套种紫花苜蓿、香椿植物篱处理的坡面均形成基于篱带部的篱坎,篱坎下部侵蚀较强,篱带上淤下蚀现象明显。其中小麦–花生套种香椿植物篱小区坡面形成2级植物篱淤积坎,坎宽幅平均达到420.8cm,淤积坎相对高差为40.4cm,平均坡度下降1.4度。小麦–花生套种紫花苜蓿植物篱坡面形成4级篱坎,平均坎宽幅为210.3 cm,平均相对高度为110.6 cm,平均坡长为238.1 cm,平均坡度下降0.3度。说明坡耕地采用植物篱技术能够减蚀截淤,显著改变微地形。针对微地形的变化,套作植物篱的坡耕地在后期宜实行坡改梯或梯级坡地配套完善灌排设施,利用已优选的植物品种设计木本与草本套种的复合植物篱,有望进一步改善土体根系分布,从而稳固篱坎,控制水土流失。该研究为植物篱技术后续管理措施优化提供了参考依据。

紫色土坡耕地地埂草篱根系土壤抗蚀与抗冲性能特征研究

为探明紫色土坡耕地不同地埂草篱根系土壤抗蚀和抗冲性的差异,以拉巴豆和紫花苜蓿地埂草篱为研究对象,以未种植草篱地埂为对照(CK),系统性地研究了土壤抗蚀和抗冲性能对草篱种类的响应,阐明了二者与根系形态特征及土壤理化性质间的耦合关系。结果表明:1)拉巴豆整株根系长度、根表面积和土壤有机质含量显著高于紫花苜蓿,且土壤含水率、总孔隙度和非毛管孔隙度显著高于紫花苜蓿和CK(P<0.05);2)土壤水稳性团聚体平均质量直径、平均几何直径及微团聚体团聚度大小表现为拉巴豆>紫花苜蓿,水稳性团聚体结构破坏率和微团聚体分散系数大小表现为紫花苜蓿>拉巴豆;3)拉巴豆土壤抗冲指数及抗冲指数变化值均大于紫花苜蓿,抗冲指数是冲刷时间的对数函数,抗冲指数变化值是冲刷时间的二次函数;4)冗余分析的结果表明整株分叉数、根尖数、土壤有机质及非毛管孔隙度对土壤抗蚀和抗冲性能的影响较大,逐步回归的结果表明>0.5 mm的水稳性团聚体结构破坏率是影响土壤抗冲指数的决定因子。综上,拉巴豆地埂草篱土壤抗蚀和抗冲性能优于紫花苜蓿。本研究可为紫色土坡耕地地埂草篱技术的推广应用提供理论依据。

植物篱对土壤养分流失的控制机理研究

植物篱是一种能有效减少地表径流、保土蓄水的水土保持措施,但其控制土壤养分流失相关机理的研究甚少。2001年在长江上游支流吒溪河的二级支流王家桥小流域设立的6个香根草(Vetiveriazizanioides)植物篱试验小区中进行地形测量及采样分析,拟通过局部地形变化、土壤颗粒和养分在小区内的空间分布变化来分析植物篱对紫色土区土壤养分流失的控制机理。坡型测量结果表明,植物篱带前出现泥沙堆积,说明植物篱能有效阻止侵蚀泥沙的向下搬运;机械组成分析结果表明,侵蚀影响下的土壤颗粒粒径在空间上出现分布差异,侵蚀剧烈的局部>0.2mm土壤颗粒明显富集,而植物篱对不同粒径的土壤颗粒的流失均有控制效果,但对粒径较大的颗粒的流失控制效果更明显;全量养分和速效养分含量空间分布的分析结果则表明,植物篱对土壤养分流失具有明显的控制作用。