东北黑土坡耕地土壤化学计量特征变化对侵蚀的响应

Response of Soil Stoichiometric to Soil Erosion on Slope Farmland in Black Soil Region of Northeast China

[目的]探究土壤侵蚀对土壤养分含量及其化学计量比的影响,对于加深认识黑土区坡耕地质量退化过程及防控具有重要意义。[方法]选择典型黑土区克山县开垦100多年的直形坡和开垦50多年的凸形坡为研究对象,根据137Cs示踪技术估算坡耕地土壤侵蚀速率,定量分析土壤侵蚀与土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量及生态化学计量比的关系。[结果](1)利用137Cs示踪法得到坡面整体的年平均侵蚀速率为4428.56 t/(km^(2)·a),直形坡和凸形坡侵蚀速率平均值分别为3284.53,5884.59 t/(km^(2)·a),侵蚀总量分别为3.21×10^(5),2.94×10^(5)t/km^(2)。(2)坡面整体碳氮比(C/N)与SOC呈极显著正相关(p<0.01),碳磷比(C/P)与SOC呈极显著正相关(p<0.01),氮磷比(N/P)与TP呈极显著负相关(p<0.01)。直形坡SOC、TN、C/N、C/P和N/P均极显著小于凸形坡养分含量和化学计量比值(p<0.01),TP含量大于凸形坡TP含量(p<0.01)。(3)坡面土壤侵蚀空间分布特征与土壤有机碳、全氮及全磷的空间分布具有一致性。坡面土壤侵蚀量与SOC、TN、TP、C/P均呈极显著负相关(p<0.01),与C/N呈显著负相关(p<0.05),与N/P呈负相关但相关性不显著(p>0.05)。[结论]土壤侵蚀导致坡面土壤SOC、TN和TP在坡面再分布,影响土壤养分化学计量比,造成坡面养分流失严重。

[Objective]The impact of soil erosion on nutrient content and stoichiometric ratios in soil is crucial for further comprehending and effective control of quality degradation in the sloping farmlands of black soil regions.[Methods]Selecting straight slopes cultivated for over a century and a convex slope cultivated for more than five decades in the typical black soil area of Keshan County as the research objects,utilizing 137 Cs tracing method to estimate soil erosion rates on the slopes.Quantitative analysis was conducted on the relationship between soil erosion and key parameters such as soil organic carbon(SOC),total nitrogen(TN),and total phosphorus(TP)contents,along with the stoichiometric ratio in the ecological chemistry.[Results](1)Using 137 Cs tracing technique,the average annual erosion rate of the whole slope was 4428.56 t/(km^(2)·a),the average erosion rates of the linear and convex slopes were 3284.53,5884.59 t/(km^(2)·a),and the total erosion volumes were calculated at 3.21×10^(5),2.94×10^(5)t/km^(2),respectively.(2)The overall carbon/nitrogen ratio(C/N)on the slopes showed a highly significant positive correlation with SOC(p<0.01),and the carbon/phosphorus ratio(C/P)correlated positively and significantly with SOC(p<0.01).Conversely,the nitrogen/phosphorus ratio(N/P)demonstrated a highly significant negative correlation with TP(p<0.01).On linear slopes,SOC,TN,C/N,C/P and N/P were significantly lower than those on convex slopes(p<0.01),while TP content was higher than that on convex slopes(p<0.01).(3)The spatial distribution characteristics of soil erosion on the slopes align with the distribution of SOC,TN and TP.The amount of soil erosion on the slopes exhibited a highly significant negative correlation with SOC,TN,TP and C/P(p<0.01),and a significant negative correlation with C/N(p<0.05).The correlation with N/P is negative,though not statistically significant(p>0.05).[Conclusion]Ultimately,soil erosion redistributed SOC,TN and TP on the slopes,affecting the stoichiometric ratios of soil nutrients and leading to substantial nutrient loss on the slopes.