简介：TheroleoforganicmatterintheformationandstabilityofsoilaggregatesinmulberryplantationintheHang-Jia-HuPlain,northernZhejiangProvince,wasevaluatedinthisstudy.Apositivecorrelationwasfoundbetweenwater-stableaggregatecontentsandorganicmattercontentsinthemulberryplantationsoils,whichsupportedthehypothesisthatorganicmatterwasthemaincementingagentinformationofaggregates.Aclosecorrelationwasalsofoundbetweenstabilityofaggregateandorganicmattercontents.Regressionanalysisshowedthattotalnitrogencontentwasalsoanindicatorofwater-stableaggregatecontentandstability.Theaggregatesizedistributionindicatedthatthewater-stableaggregates1～0.25mmindiameterwerethemajorcomponentoftheaggregatesinthemulberryplantationsoils.Theorganicmattercontentsofaggregatesrangingfrom5to0.25mmindiameterincreasedwiththedecreaseofaggregatesizes,andtheaggregates1～0.25mmindiameterhadthemaximumorganicmattercontent.

简介：我们在一条森林道路的不同部分测量了erodibility和土壤总数的吝啬的重量直径(MWD)。表层土的样品从cutslope，fillslope，估计质地的道路表面和森林地面，体积密度，潮湿，CaCO3和有机物被收集。土壤总数稳定性被湿sieving决定。道路表面上的土壤erodibility分别地比在fillslope和cutslope上高2.3和1.3倍。森林土壤有最低erodibility。cutslope和道路表面的总数稳定性分别地低、很低。在有CaCO3和沙内容的cutslopeerodibility之间有一种重要否定关系。Cutslopeerodibility与增加淤泥，泥土和潮湿内容增加了。在fillslopes上，MWD与增加岩石碎片盖子，植物盖子，崽盖子，有机物和沙增加了。在fillslopeerodibility和有机物之间有强壮的否定关联，沙和MWD。在悬钩子属植物hyrcanusL下面赤裸的土壤和土壤的erodibility之间没有重要差别。并且Philonotismarchica(Hedw)Brid。

简介：Theobjectivesofthepresentstudyweretoexaminethespatialpatternsofswarddrymatter(DM)andnitrogen(N)yieldsinagrasssilagefieldatfirst,second,andthirdcutsovera3-yearperiod;quantifytheirtemporalstabilitieswithtemporalstabilitymaps;andassessthepotentialforsite-specificmanagementineachpasture-growingperiodusingclassifiedmanagementmaps.Atcut1,thespatialpatternsofDMandNyieldsprovedtobewelldefinedandtemporallystableandwerelikelytobeduetodifferencesinthenetNmineralizationratesacrossthefieldduringspring.Incontrast,atcut2,thepatternsofDMproductionwerepatchyandtemporallyunstable.Itwasconcludedthat,inprinciple,asimplesite-specificapproachtoNfertilizationwouldbepossibleinthisfieldduringspringatcut1.Atlaterharvests,therationaleforasite-specificapproachtofertilizermanagementwaslessclearwithlogisticsappearingtobemorecomplexandlessfeasible.

简介：

简介：Soilaggregatestability,animportantindexofthephysicalcharacteristicsofasoil,canprovideagoodindicationofasoil’serodibility,anddeservesspecialconsiderationinregionswithcoldclimate.Theobjectiveofthisstudywastostudytheeffectoffreeze-thawonsoilwater-stableaggregatesintheblacksoilregionofNortheastChina.Samplesofatypicalblacksoilintheregionwerecollectedtomeasurewater-stableaggregatesafterfreeze-thawunderdifferentconditions(i.e.,initialmoisturecontents,freezethawcyclesandfreezingtemperatures)bywet-sievingintoeightparticlesizegroups(>10,10–6,6–5,5–3,3–2,2–1,1–0.5,and0.5–0.25mm).Freeze-thawhadthemosteffectonaggregatestabilitywhenthesampleshadaninitialmoisturecontentof400gkg-1.Thewater-stableaggregatesofthefourlargerparticlesizegroups(>5,5–3,3–2,and2–1mm)reachedapeakstabilityvalue,butthoseofthetwosmallerparticlesizegroups(1–0.5and0.5–0.25mm)reachedaminimumvaluewhenthesoilmoisturecontentwas400gkg-1.Water-stableaggregatesofthefourlargerparticlesizegroupsdecreasedwhilethoseofthetwosmallerparticlesizegroupsincreasedwiththeincreaseoffreeze-thawcycles.Astemperaturesfell,thewater-stableaggregatesofthefourlargerparticlesizegroupsdecreasedwhilethoseofthetwosmallerparticlesizegroupsincreased.

简介：WhenbeingplantedinwideareasinsouthernChina(23°23'-33°23'N,98°35’-129°19'E,sealevelabove2.7-1285m),Liangyoupeijiu(LYPJ),atwo-linehybridricecombination,showedaseedsettingrateof75.2-77.2%,whichwaslowerby4.3-7.5percentpointthanthatofanindicahybridriceShanyou63(CK),withsimilarvaluesofgrainyieldandcoefficientsofvariationtoCK.Sowingduring5-25thofMayinNanjing(32°3'N.118°48'E),China,LYPJheadedbefore4thSeptember,andgaveaseedsettingrateof75-90%,andgrainyieldover1kg/m^2.Ifthesowingdatewasdelayedto14-15th,June,itsheadingdatewouldbeaslateas17th-21stSeptember,andseedsettingratewouldbedeclinedby10-15%incomparisonwiththatonasuitablesowingdate.Whenfloweringtookplaceatanaveragedailytemperaturerangeof13.7-28.5℃forfivedays,thespikeletfertility(SF)wouldbeincreasedby1.9-10.7%,foreachincrementof1℃.Thesuitable(SF≥90%)andsafe(SF≥75%)temperaturesforfloweringstagewereindicatedtobe26.5°and22.9°,respectively.TogetahighandstableseedsetincultivatingLYPJ,itwasrecommendedthatLYPJwouldbeplantedintheareassouthof34°N,andthefavorableaveragedailytemperatureduringfloweringstageshouldbeat26-28℃.

简介：该研究采用传统热压和喷蒸热压两种方法来生产杨木刨花板．刨花板内施加１０％的脲醛树脂胶（ＵＦ），目标厚度分别取１０，１５，２０，和２５ｍｍ，热压温度均为１８０℃．喷蒸热压时饱和蒸汽的压力为０．３～０．５ＭＰａ，每种厚度下喷汽时间一定，取两个热压时间；传统热压时每种厚度下各取４个热压时间．然后测定试件的吸水厚度膨胀率、吸水率、密度、含水率及力学性能．本文重点讨论了喷蒸热压对杨木刨花板尺寸稳定性的影响．结论认为：喷蒸热压相对于传统热压，在保证刨花板的强度、缩短热压时间的条件下，明显改善了杨木刨花板的尺寸稳定性．