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

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：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.