退耕植茶地土壤碳氮磷生态化学计量学特征

研究不同退耕植茶年限土壤有机碳、全氮和全磷的质量分数分布及其生态化学计量学特征,以期为退耕植茶地土壤持续利用和茶园持续发展提供理论依据。选取退耕植茶2~3 a(RT2-3), 9~10 a(RT9-10)和16~17 a(RT16-17)的各5个样地为研究对象,以邻近耕地作为对照,采用野外调查与室内分析相结合的方法,按0~10,10~20和20~40 cm土层取样,测定土壤有机碳、全氮、全磷的质量分数,并计算了碳、氮、磷之间的计量比。结果表明:随着退耕植茶年限的延长,土壤有机碳、全氮质量分数表现为先显著降低后增加的趋势(P<0.05),全磷质量分数变化较为稳定。0~10 cm土层,退耕植茶地土壤碳氮比(C/N)显著高于对照地,退耕植茶地土壤碳磷比(C/P)和氮磷比(N/P)显著低于对照地;10~20 cm土层,退耕植茶地土壤碳氮比显著高于对照地,碳磷比在各样地间均无显著差异,氮磷比则表现为对照地土壤显著高于退耕植茶地;20~40 cm土层,碳氮比表现为RT2-3显著高于其他样地,碳磷比和氮磷比在各样地间均无显著差异。退耕植茶后,土壤碳氮比显著增加,有机质分解速率降低。退耕植茶有利于土壤有机碳、全氮的积累;虽有利于提高土壤中磷的有效性,但随着植茶年限的延长,磷素对退耕植茶地限制性逐渐增强。

Ecological stoichiometry of soil C,N, and P for returning farmland to tea plantations

To provide a scientific basis for sustainable use of soil and sustainable development of tea plantations, soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) at different ages (2-3, 9-10, and 16-17 years old) were measured in returning farmland to tea with elemental changes in the soil profile of the tea plantations noted. Three tea plantations with different ages located in Zhongfeng Township of Mingshan District were selected as the study plots, and the near cropland was used as contrast. Adopting field investigation and indoor analysis methods, soil samples were collected from 0-10, 10-20, and 20-40 cm depths with SOC, TN, and TP being analyzed and C:N, C:P, and N:P ratios being estimated. ANOVA was performed using the DPS software (7.05). Two-way ANOVA, followed by the least significant difference (LSD) test (P<0.05), was used to compare the sites representing the different tea plantations age and soil layer. Results showed that after returning farmland to tea, SOC content and TN significantly decreased first (P<0.05) and then increased (P<0.05); whereas, changes of TP were relatively stable (P<0.05). In the 0-10 cm soil layer, C:N of returning farmland to tea was significantly higher than the control (P<0.05); whereas C:P and N:P were significantly lower than the control (P<0.05). In the 10-20 cm soil layer, C:N of returning farmland to tea was significantly higher than the control (P<0.05). In the 20-40 cm soil layer, C:N for returning farmland to tea (2-3 years old) was significantly higher than other plots (P<0.05). Also, after returning farmland to tea, the artificial disturbance decreased, which resulted in the degradation of organic matter decomposition rate. Therefore, returning farmland to tea was beneficial to SOC and TN accumulation, improved P efficiency, but limited P on tea plantations which became problematic overtime.