湘东地区水耕人为土的碳氮磷化学计量学特征

Stoichiometry Characteristics of Carbon,Nitrogen and Phosphorus of Stagnic Anthrosols in East Hunan Province

为了解水耕人为土碳氮磷的元素组成及其养分限制作用,通过调查湘东地区不同母质发育的水耕人为土,野外共挖掘39个样点的土壤剖面并采集不同发生层的土壤样品,研究区域尺度上母质、土类和发生层对土壤有机碳(SOC)、全氮(TN)和全磷(TP)含量及其化学计量比的影响。结果表明,水耕人为土耕作层SOC、TN (二级水平)和TP (一级水平)含量丰富。虽然SOC与TN的相关性显著,但SOC与TP、TN与TP却无显著相关性,水耕人为土中也没有存在稳定的C∶N∶P。C∶N剖面加权平均值的范围介于6. 30～31. 38 (均值为11. 22),C∶P介于1. 91～29. 79 (均值为11. 62),N∶P介于0. 12～2. 70 (均值为1. 05)。母质对水耕人为土的碳氮磷化学计量比无显著影响。潜育水耕人为土的C∶N、C∶P和N∶P均显著高于简育、铁聚水耕人为土,这显示出土类强烈地影响土壤碳氮磷的化学计量比。随着土壤剖面的加深,C∶N、C∶P和N∶P均显著降低,SOC降幅远高于TN和TP,底土中氮、磷的限制作用减弱。本研究表明,水耕人为土氮磷的限制作用可能与母质无关,但受到土类和土壤发生层的强烈影响。

In order to understand the elemental composition of organic carbon （SOC）, total nitrogen （TN）, and total phosphorus （TP） in stagnic anthrosols and related nutrient limiting factors, totally 39 sites of stagnic anthrosols were surveyed in the field, and soil samples in genetic horizons were collected by excavating profile technology in east Hunan Province. The influence of parent material, soil group, and soil genetic horizon on SOC, TN, TP content, and their stoichiometry （C∶ N, C∶ P, and N∶ P ） at regional scale were researched. Results showed that the plough layer was rich in SOC, TN and TP which fell into the high grade level of soil nutrient in rice field. The SOC content was highly significantly correlated with TN content. But no significant correlations were found between SOC and TP contents, and between TN and TP contents. This indicated there was no stable C∶ N∶ P in stagnic anthrosols. The weighted average C∶ N, C∶ P , and N∶ P of soil profile was ranged from 6.30 to 31.38 （mean value of 11.22）, from 1.91 to 29.79 （mean value of 11.62）, and from 0.12 to 2.70 （mean value of 1.05）, respectively. Parent material showed no significantly influence on C∶ N, C∶ P, and N∶ P. While C∶ N, C∶ P and N∶ P in gleyic stagnic anthrosols were higher than those in typic and Fe-accumulic stagnic anthrosols, implying the strong influence of soil group. Besides, C∶ N, C∶ P and N∶ P were decreased with soil depth. The SOC content, however, decreased great higher than TN and TP contents, showing the decreased limiting of N and P in subsoil. This study suggests that the limitation of N and P in stagnic anthrosol was weaker than that in natural soil. And this limitation was affected by the soil group and genetic horizon rather than the parent material.