青藏高原高寒草甸不同季节土壤理化性质及酶活性对施肥处理的响应

Tibetan Plateau alpine meadow soil properties and enzyme activity in response to fertilization gradients in different seasons

关键词:  青藏高原  高寒草甸  施肥梯度  土壤理化性质  土壤酶活性

Key words:  Tibetan Plateau  alpine meadow  fertilization gradients  soil properties  soil enzyme activity

摘要:

分析了青藏高原东缘高寒草甸不同施肥处理对土壤全量养分、速效养分、pH、含水量、有机碳和土壤脲酶活性的影响,以揭示高寒草甸土壤养分和酶活性对施肥的响应。结果表明:(1)随施肥量的增加,土壤pH明显趋于降低,施肥引起高寒草甸土壤酸化; 全磷、速效磷均显著增大;(2)土壤全氮、有机碳和脲酶活性随施肥量增加呈单峰曲线变化,在施肥量为30或60 g·m^-2时最高,施肥量增加到90 g·m^-2时土壤资源逐渐降低;(3)季节变化对土壤养分也有一定的影响,全氮和全磷含量均于9月份较高,而速效氮含量一般于9月份较低,而速效磷含量5月份较低;(4)施肥对土壤养分的影响并不是简单的线性正相关关系,30～60 g·m^-2施肥量可作为高寒草甸最佳施肥水平。施肥处理下土壤有机碳和脲酶活性可作为衡量土壤肥力和土壤质量变化的重要指标。高施肥量(≥90 g·m^-2)可作为影响高寒草甸土壤养分及土壤酶活性的阈值。

Abstract:

Different fertilization gradients affect to the soil total nutrient,available nutrients,pH,water content,organic carbon and soil urease activity in alpine meadow in Maqu area were studied. To reveal the alpine meadow soil nutrient and enzyme activity in response to fertilization gradients. The results were as follows:(1)With the increase of fertilization gradients,soil pH tended to reduce obviously,fertilizing caused soil acidification in grassland ecosystem,total phosphorus and rapid available phosphorus increased obviously as the increase of fertilization gradients;(2)Soil total nitrogen,organic carbon and urease activity changed as a single peak curve as the increase of fertilization gradients. It was higher in the fertilizer gradients of 30 or 60 g·m^-2,and the soil resources gradually reduced in the fertilizer gradient of 90 g·m^-2;(3)Seasonal variation had a certain influence on soil nutrients,total nitrogen and total phosphorus content were higher in September,The available nitrogen content was generally lower in September,available phosphorus was lower in May;(4)The influence of fertilizer application on soil nutrients was not simple linear positive correlation. The fertilization gradients of 30-60 g·m^-2 could be used as the best fertilizer levels in alpine meadow. Soil organic carbon and urease activity could be used as the important indicators to measuring soil fertilizer and soil quality in fertilization gradients. High rate of fertilization(≥90 g·m^-2)can be regarded as the threshold to effect the structure and function in alpine meadow,soil nutrient and soil enzyme activity.