黄土丘陵区不同土地类型下土壤养分特征—基于生态化学计量学

为探讨黄土丘陵区不同土地类型下土壤有机碳（SOC）、全氮（TN）、全磷（TP）含量特征，本研究以黄土丘陵区典型小麦地、云杉林地、苜蓿地为对象，基于实测数据，采用方差、相关统计分析，研究不同土地类型、不同土层深度（0~10 cm、10~20 cm、20~40 cm、40~60 cm、60~80 cm、80~100 cm）土壤SOC、TN、TP含量及其化学计量比。结果表明：3种不同土地类型土壤SOC、TN和TP含量均随土层深度增加而降低，其平均含量分别为12.19、0.33和0.48 g·kg^-1，小麦地和苜蓿地土壤SOC、TN和TP空间变异性较云杉林地偏大。SOC、TN含量为云杉林地>小麦地>苜蓿地，TP含量为云杉林地>苜蓿地>小麦地。土壤SOC、TN和TP间均存在显著正相关关系。小麦地C/P显著（P<0.05）高出苜蓿地41.96%，N/P显著高出云杉林地、苜蓿地28.57%、36.19%。3种不同土地类型土壤化学计量比（C/N、C/P、N/P）均值分别为：39.61、31.53、0.83，且其C/N大于中国平均值（12.3），C/P、N/P较全国平均值（61.0、5.2）明显偏小，黄土丘陵区C/N较稳定。土地类型对土壤C、N、P含量及其化学计量比存在不同程度的影响，合理调整土地利用结构有助于土壤养分的存留，有利于土壤生态的恢复。

Characteristics of soil nutrients under different land types in the loess hill region based on ecological chemometrics

This research aimed to explore the characteristics of soil organic carbon(SOC),total nitrogen(TN),and total phosphorus(TP)under different land types in the loess hill region.Sites classed as typical wheat land,spruce woodland,and alfalfa land in the loess hill region were identified and SOC,TN,and TP levels and their stoichiometric ratio for the different land types and soil depths(0-10 cm,10-20 cm,20-40 cm,40-60 cm,60-80 cm,80-100 cm)were evaluated.Based on the measured data,variance and relevant statistical analysis were conducted.It was found that SOC,TN,and TP concentrations in all three land types decreased with increasing soil depth,and their average contents were 12.19,0.33,and 0.48 g·kg^-1,respectively.The spatial variability of SOC,TN,and TP at wheat and alfalfa land sites was larger than that in spruce forest.The ranking for SOC and TN was spruce woodland>wheat field>alfalfa field,and the TP concentration ranked spruce woodland>alfalfa field>wheat field.A significant positive correlation was found between SOC,TN,and TP.The wheat field C∶P ratio was higher than that of the alfalfa field by 41.96%(P<0.05),while the N∶P ratio of wheat land was significantly higher than that of spruce woodland and alfalfa fields by 28.57%and 36.19%,respectively.Averaged over the three different land types,the values of the soil stoichiometric ratios(C∶N,C∶P,and N∶P)were 39.61,31.53,and 0.83,respectively.The value for C∶N is greater than the average for greater China(12.3),while values for C∶P and N∶P are significantly smaller than the national average(61.0,5.2,respectively).The C∶N value in the loess hill region is relatively stable.Land use types have distinctive C,N,and P content signatures and stoichiometric ratios.Appropriate adjustment of land use structure is conducive to the retention of soil nutrients and can potentially improve soil ecological status.