简介：Thereareabout1.27millionhaofuplandredsoilsderivedfromQuaternaryredclayfacingthedegradationinthelow-hillyregionofthemiddlesubtropicalChina.Fromtheaspectsofchemistry,physicsandmicrobiology,theprocessesofsoilfertilityrestorationinthesurfacelayer(0-20cm)underthreetypesoflandusepatterns(i.e.citursorchard,teagardenandupland)intwoprovinceswerestudiedinthiswork.Resultsshowedthatthereclamationoferodedwastealdnimprovedmostofsoilproperties.Soilorganicmatter,totalNandP,availablePandK,andexchangeableCaandMgincreased,butsoiltotalKandexchangeableAldecreasedSoilpHdecreasedby0.5unitinthepureteaplantationfor20years.Soilreclamationincreasedthepercentageofsoilmicreasedby0.5unitinthepureteaplantationfor20years.Soilreclamationincreasedthepercentageofsoilmicroaggregates(<0.25mm),especiallythosewithadiameterof0.02-0.002mm.Soiltotalporosityincreasedinthecultivatedlandswiththeincreaseofsoilaerationandcapillaryporosity,Thenumberofsoilmicroorganismsincreasedwithreclamationcausedmainlybythehugeincreaseofthetotalamoutofbacteria,Withthecultivation,theeativityofsoilureaseandacidphosphataseincreased.butthatofinvertasedropped.

简介：中国经历了使用在最近的十年改变的戏剧的土地，与显著环境、社会经济的后果。Hengshan县，在西北中国的风神黄土的区域定位了，被调查为环境、长期的农村经济开发说明陆地使用变化和他们的含意。在Hengshan县的农田显著地减少了在期间19902003，而森林土地和草地增加了。土地在不同时期之中显著地改变了的农田，果园陆地，森林陆地和建设的变换率：19901995，19952000和20002003。果园土地，草地和构造土地的变换是主导的在19901995，而到森林土地的农田的变换主要发生了在20002003。结果在机构的政策和陆地管理的政治经济建议了深刻转变，包括综合土壤侵蚀控制工程，面向市场的经济的采纳和‘Grain-for-Green'政策的实现，在在中国的这个时期期间。为了完成长期的持续土地，在Hengshan使用县，努力应该瞄准象建立节俭陆地的机制支持陆地生产率一样增加农村家庭的离开农场收入，除了保存措施。

简介：Soilmicrobialbiomassandcommunitystructuresarecommonlyusedasindicatorsforsoilqualityandfertility.Ainvestigationwasperformedtostudytheeffectsoflong-termnaturalrestoration,cropping,andbarefallowmanagementsonthesoilmicrobialbiomassandbacterialcommunitystructuresindepthsof0–10,20–30,and40–50cminablacksoil(Mollisol).Microbialbiomasswasestimatedfromchloroformfumigation-extraction,andbacterialcommunitystructuresweredeterminedbyanalysisof16SrDNAusingpolymerasechainreaction-denaturinggradientgelelectrophoresis(PCR-DGGE).Experimentalresultsshowedthatmicrobialbiomasssignificantlydeclinedwithsoildepthinthemanagementsofrestorationandcropping,butnotinthebarefallow.DGGEprofilesindicatedthatthebandnumberintop0–10cmsoilswaslessthanthatindepthof20–30or40–50cm.Thesesuggestedthatthemicrobialpopulationwashighbutthebacterialcommunitystructurewassimpleinthetopsoil.ClusterandprinciplecomponentanalysisbasedonDGGEbandingpatternsshowedthatthebacterialcommunitystructurewasa?ectedbysoildepthmoreprimarilythanbymanagements,andthesuccessionofbacterialcommunityasincreaseofsoildepthhasasimilartendencyinthethreemanagements.FourteenpredominatingDGGEbandswereexcisedandsequenced,inwhich6bandswereidentifiedasthetaxaofVerrucomicrobia,2bandsasActinobacteria,2bandsasα-Proteobacteria,andtheother4bandsasδ-Proteobacteria,Acidobacteria,Nitrospira,andunclassifiedbacteria.Inaddition,thesequencesof11DGGEbandswerecloselyrelatedtounculturedbacteria.Thus,thebacterialcommunitystructureinblacksoilwasstable,andthepredominatingbacterialgroupswereuncultured.