简介:Withdecreasingavailabilityofwaterforagricultureandincreasingdemandforriceproduction,anoptimumuseofirrigationwaterandphosphorusmayguaranteesustainablericeproduction.Fieldexperimentswereconductedin2003and2004toinvestigatetheeffectofphosphorusandirrigationlevelsonyield,waterproductivity(WP),phosphorususeefficiency(PUE)andincomeoflowlandrice.Theexperimentwaslaidoutinrandomizedcompleteblockdesignwithsplitplotarrangementsreplicatedfourtimes.Mainplotconsistedoffivephosphoruslevels,viz.0(P0),50(P50),100(P100),150(P150),and200(P200)kg/hm2,whilesubplotscontainedofirrigationtimes,i.e.8(I8),10(I10),12(I12),and14(I14)irrigationlevels,eachwithawaterdepthof7.5cm.MeanvaluesrevealedthatP150incombinationwithI10producedthehighestpaddyyield(9.8t/hm2)andnetbenefit(1231.8US$/hm2)amongallthetreatments.PhosphorusenhancedWPwhenappliedinappropriatecombinationwithirrigationlevel.ThehighestmeanWP[13.3kg/(hm2?mm)]couldbeachievedatP150withI8anddecreasedwithincreaseinirrigationlevel,whilethehighestmeanPUE(20.1kg/kg)couldbeachievedatP100withI10anddiminishedwithhigherPlevels.TheoverallresultsindicatethatP150alongwithI10wasthebestcombinationforsustainablericecultivationinsiltyclaysoil.
简介:依据国家标准GB/T18972—2003《旅游资源分类、调查与评价》,在海南白沙旅游资源调查基础上,根据对旅游资源单体的评价,得出该单体旅游资源共有综合因子评价赋分值并对其分级,结果表明:白沙旅游资源分为8大主类,24个亚类、54个基本类型,分别占国标旅游资源分类同类项的100%、77.42%、34.84%;69个重要单体其中特品级旅游资源有3个、优良级旅游资源36个、普通级旅游资源30个,分别占单体总数的4.35%、52.17%、43.48%一些单体同时具备多个主类、亚类、基本型的特征。根据白沙旅游资源的分布特征,将其分为3个功能区,建议有重点的逐步开发。