紫色土区典型土地利用方式下土壤碳、氮、磷生态化学计量特征分析

Soil Carbon,Nitrogen and Phosphorus Stoichiometry Characteristics under Typical Land Uses in Purple Soil Area

为明确紫色土区不同土地利用方式对土壤碳(C)、氮(N)、磷(P)质量分数及其生态化学计量比变化的影响,对比分析了3种典型土地利用方式(林地、园地、耕地)下,不同土层(0~5,5~10,10~15,15~20 cm)C,N,P质量分数及其生态化学计量比变化特征及其影响因素.研究结果表明:0~5 cm土层,林地C及园地N质量分数均显著高于耕地(p<0.05),而5~10,10~15,15~20 cm土层C,N质量分数差异均无统计学意义(p>0.05);在所有土层中,园地P质量分数显著高于林地、耕地(p<0.05).研究区土壤C∶N,C∶P,N∶P均值分别为10.63,36.08,3.32,皆低于中国与全球土壤均值.0~5 cm土层,林地C∶N,C∶P,N∶P显著高于园地(p<0.05);5~10,10~15,15~20 cm土层,耕地C∶P,N∶P显著高于园地(p<0.05).相同土地利用方式下0~5 cm土层的C,N,P质量分数均显著高于5~10,10~15,15~20 cm土层(p<0.05),但C∶N,C∶P,N∶P差异无统计学意义(p>0.05).土壤容质量、pH值、含水率与土壤C,N质量分数相关性有统计学意义(p<0.05),电导率、阳离子交换量与土壤P质量分数、C∶P、N∶P相关性有统计学意义(p<0.05).研究区林地土壤C,N,P比例相对更均衡,土壤理化性质间存在显著相互作用,N为该区域土壤养分限制性元素.

In this study,the effects of different land uses on soil carbon(C),nitrogen(N),phosphorus(P)contents and stoichiometry ratios as well as their influencing factors were determined.Soil samples were collected from three representative land uses including forest land,garden,arable land at different soil layers(i.e.0-5,5-10,10-15,15-20 cm).C content in forest land soil and N content in garden soil were significantly higher than those of in arable land soil at 0-5 cm soil layer(p<0.05),while the variations of C and N contents were not significant among 5-10,10-15,15-20 cm soil layers(p>0.05).P content was significantly higher in garden soil than in forest and arable land soils across four soil layers(p<0.05).The average values of soil C∶N,C∶P and N∶P were 10.63,36.08 and 3.32 in the study area.which are lower than the Chinese and global averages,respectively.C∶N,C∶P and N∶P were significantly higher in forest land soil than in garden soil(p<0.05)at the 0-5 cm soil layer,and C∶P and N∶P were significantly higher in arable land soil than garden soil at 5-10,10-15,15-20 cm soil layers(p<0.05).C,N and P contents were significantly higher at the 0-5 cm soil layer than those in other three soil layers(p<0.05),but C∶N,C∶P and N∶P were not significant among all soil layers(p>0.05)under the same land use.Soil bulk density,pH and soil moisture content were significantly correlated with soil C and N contents(p<0.05),while electron conductivity and cation exchange capacity were significantly correlated with soil P content,C∶P and N∶P(p<0.05).The results indicated that the proportion of C,N and P was much more balanced in the forest land than in garden and arable lands.There was significant interaction among soil physical and chemical properties.Nitrogen was the limiting soil nutrient element in the study area.