干热河谷土壤酶活性和车轴草生长对氮磷添加的响应

为了探讨干热河谷地区不同土地利用类型下土壤酶活性和植物生长对氮磷添加的响应以及二者之间的联系,采集了元谋干热河谷6种不同土地利用类型土壤,包括灌丛、草地、森林、新开垦农田(新农)、常年耕作农田(常农)、侵蚀裸地(裸地),并利用盆栽探索了土壤酶活性和车轴草(Trifolium repens L.)生长对氮(N)、磷(P)、氮磷(N+P)处理的响应特征。结果表明:(1)植物生物量受土地利用类型和处理双重因素影响,两者的交互作用对植物生物量具有显著作用。(2)除农田土壤(新农和常农)外,其他土地利用类型的土壤上植物生长受到养分添加的显著影响,其中添加P处理的生物量显著高于对照; 而N+P处理又显著高于单一的P添加; 而新农和常农不同养分处理间植物生物量差异不显著。(3)土壤酶活性受土地利用类型显著影响,但是不同养分添加处理之间土壤酶活性差异不显著; 土壤酶活性与植物生物量无显著相关性。综上,干热河谷土壤中植物生长的限制养分主要为磷,然而土壤酶活性则不受氮磷养分的限制,其活性主要与土地利用类型有关。

Response of Soil Enzyme Activities and Trifolium repens L. Growth to Nitrogen and Phosphorus Addition in Dry and Hot Valley

This study aims to explore the effects of nitrogen and phosphorus addition on soil enzyme activities and plant growth under different land use types in dry and hot valleys, and the association between soil enzyme activities and plant growth. Soils in 6 different land-use types including shrubs, grasslands, forests, new farming, permanent farming, eroded bare land in Yuanmou dry-hot valley were collected. Pot experiment was used to explore the response characteristics of soil enzyme activities and Trifolium repens L. growth to treatments of nitrogen(N), phosphorus(P), and nitrogen and phosphorus(N+P). The results show that:(1)plant biomass was affected by both land use types and fertilizer treatments as well as their interactions;(2)there were significant differences in plant growth of nutrient addition in land use types except for soils from farmlands(new farming and permanent farming); the plant biomass of P treatment was significantly higher than that of CK; the plant biomass of N+P treatment was significant higher than that of single application of P fertilizer; however, the differences in plant biomass among different treatments for soils from new farming and permanent farmland were not significant;(3)soil enzyme activities were significantly affected by land use types, but there were no significant differences in soil enzyme activities among different nutrient addition treatments; there was no significant correlation between those soil enzyme activities and plant biomass. In conclusion, plant growth was primarily limited by phosphorus on soils in this dry and hot valley. However, soil enzyme activities were not limited by phosphorus or nitrogen, but mainly affected by land use types.