摘要
１９８０～１９８６年在青海省海拔３２５０～３７６８ｍ的牧区设４个点，对６种常见栽培禾本科牧草进行了施氮量为０（ｃｋ）、３８、７５、１１３、１５０、２２５ｋｇ／ｈｍ２或０、３８、７５、１１３、１５０、２２５、３００、４５０、６００、７５０ｋｇ／ｈｍ２的试验。结果表明６种禾草的产量皆因施氮而显著提高。牧草增产量和施氮量的相关曲线的完整形式可区分为效应递增、效应递减和负效应三个阶段。在通常情况下的表现形式为效应递减阶段，当施氮水平过高时出现负效应阶段，只有在草地土壤中氮极缺且施氮量又相当低的情况下才出现效应递增阶段。其效应的变化，除了取决于施氮水平和草地土壤肥力之外，还取决于禾草种类、试点的气候条件（主要是牧草生长期的积温）和施肥后牧草被刚收利用的年次（高寒牧区１年只能刈收１次）等。在同一个点上且施肥水平同为０～２２５ｋｇ／ｈｍ２时，施氮当年高禾草的效应曲线只有递减一个阶段，而矮禾草的曲线既包括递减阶段也包括负效应阶段在内。但施氮后连续刚收２年的累积效应高、矮禾草皆为递减。
The response of six cultivated herbag6 grasses to nitrogen application was studied at 4 sites of altitudes3250～3768m in the grassland areas of Qinghai Plateau from 1980 to 1986.The species studied wereBromus inermis,Elymus sibiricus cv.foliosus cv. tiebujia,Puccinellia tenuiflora,Poa crymophia and Roegneriahisuta. The nitrogen application rates were 0,38,75,113,150,225,300,450,600,750 kg/hm2.Theresults showed that yields of all 6 grasses increased considerably as a response to nitrogen applications.However,the nitrogen efficiency i.e. yield increased per kg nitrogen,was varied with application rates.Itcould be divided into three stages:successive increase,successive decrease and negative effect.Undernormal conditions the response curve was successive decrease。It showed negative effect when N was appliedexcessively. The N efficiency was only successive increase under the extremely low N content levels in thesoil.The response to N also depended on grass species,climatic conditions(especially the accumulatedtemperature of growing season)and cutting frequency(cut only once per year in the area).At the sameexperimental site ahd N rates of 0─225 kg/hm2,in the yeat of N application,the response curve of highgrasses such as Bromus inermis was in successive decrease stage,whereas the curve of low grasses such as Poaincluded successive decrease and negative effect stage. However,the curves of accumulated yield in theperied of first 2─year after N application were all in successive decrease stages,regardless of high or low grasses.
出处
《草业学报》
CSCD
1995年第4期1-8,共8页
Acta Prataculturae Sinica
基金
青海省"六五"期间重点科技项目
关键词
高寒牧区
栽培
禾草
施氮效应
Qinghai plateau,cultivated grasses,nitrogen application,response
