9种牧草对青海同德牧区土壤特性的影响

通过对青海省高寒牧区常见的9种多年生牧草单播2年后耕层0~15cm土壤理化(pH、容重(BD)、有机碳(SOC)、全氮(TN)、无机碳(C)及微生物学性质(微生物生物量碳(Cmic)、氮(Nmic)和群落代谢功能)等指标的测定分析,结果表明,研究区域只有在种植披碱草2年后土壤有机碳含量有所增加,说明与其他草种相比,种植披碱草利于有机质的积累;试验在每年施肥1次的情况下,土壤氮含量仍然偏低,说明此区氮素被过度利用,处于缺乏水平,因此每年增施氮肥数量、频率以及时间上应加强管理。通过对不同牧草种植区土壤各因子的聚类分析,发现贫花鹅观草、无芒雀麦、紫野麦草和扁穗冰草之间相似度较高,表明其对土壤养分及微生物群落功能的影响较为接近,故在大面积种植的时候可根据牧草地上生物量/质量的高低进行选择性播种。从土壤质量方向考虑,种植杂花苜蓿、红豆草和西北羊茅不利于土地的改良。

Effects of 9 forage species on soil properties in the alpine pastoral region of Qinghai Province

The soil physiochemical properties (including soil pH,bulk density,organic carbon,total nitrogen and inorganic carbon),microbial biomass carbon and nitrogen,community functional diversity and their metabol-ic activity were all measured in the arable layer (0~1 5 cm soil)after planting 9 perennial grasses for 2 years in the alpine pastoral areas located in north-eastern Tibet Plateau.The results showed that,compared to other grasses,Elymus dahuricus was conducive to the accumulation of organic matter in the soil.The soil N was used excessively result in its insufficiency in this region,Therefor,it is necessary to strengthen the management in term of nitrogen application amount,frequency,and application time.Based on the clustering analysis of soil fac-tors,we found that Roegneriapauciflora,Bromusinermis,Hordeumviolaceum and Agropyroncristatum had higher similarity,which implied that they had similar effects on soil nutrients and microbial community.Based on the aboveground biomass or forage quality,these forages should be considered preferentially.Considering the soil quality,Medicago varia,Onobrychis viciaefolia,Festuca kryloviana were not good forages for land im-provement.