广西岩溶区芒果园土壤碳氮磷化学计量特征

【目的】探究广西岩溶区土壤养分生态化学计量特征的空间分异规律，以及岩溶区富钙偏碱的地质背景对土壤有机碳、全氮和全磷化学计量特征的影响，为揭示岩溶区土壤养分循环规律及指导科学施肥提供科学参考。【方法】在百色市田阳县芒果生产基地选择典型岩溶样地，采集洼地、洼地—坡地过渡带、坡地和垭口等不同地貌部位表层土壤样品，通过测定土壤有机碳、全氮和全磷及相关土壤元素等，运用统计学方法分析岩溶区不同地貌部位土壤碳（C）、氮（N）、磷（P）化学计量特征及影响因素。【结果】研究区土壤有机碳、全氮和全磷含量的平均值分别为17.24、2.31和0.70 g/kg，C:N、C:P和N:P平均值分别为7.43、26.11和3.44。土壤有机碳和全氮含量以坡地最高，洼地最低；全磷含量以垭口最高，从洼地、洼地—坡地过渡带和坡地呈降低趋势； C:N、C:P和N:P总体上表现为坡地>洼地—坡地过渡带>洼地>垭口。统计分析结果显示，阳离子交换量（CEC）、pH、含水率、容重及全钙含量对岩溶区土壤有机碳、全氮和全磷化学计量特征具有很好的解释。偏相关分析结果显示，钙是有机碳和全氮的重要影响因子；土壤有机碳、全氮和全磷的化学计量与CEC、全镉的相关性受钙制约；有效态元素与土壤有机碳、全氮和全磷化学计量的相关性受pH和钙的制约较小。【结论】研究区土壤碳氮磷化学计量受地貌部位影响，且土壤中全钙含量是土壤碳氮磷化学计量的重要影响因子。研究区农业生产上应选择元素有效性高的化肥施入，特别是磷元素，根据果树生长阶段需肥特点进行针对性补充。

Stoichiometric characteristics of soil carbon,nitrogen and phosphorus in mango orchard in karst area of Guangxi

【Objective】 This paper explored the spatial differentiation law of soil nutrient ecological stoichiometry characteristics in karst area and the influence of the geological background of rich calcium and alkali on soil organic carbon, total nitrogen, and total phosphorus ecological stoichiometry characteristics in karst area, providing scientific reference for revealing the soil nutrient cycling law and scientific fertilization in karst area.【Method】 Typical karst samples were selected from the mango planting base in Tianyang County, Baise City, and surface soil samples were collected from different geomorphic sites including depression, transition zone between depression and slope, slope and saddle. Soil organic carbon, total nitrogen, total phosphorusand related soil elements were measured. The stoichiometric characteristics of soil carbon(C), nitrogen(N) and phosphorus(P) and their influencing factors were analyzed using statistical method.【Result】 The average contents of organic carbon, total nitrogen and total phosphorus in the study area were 17.24, 2.31 and 0.70 g/kg respectively. The average values of C:N, C:P and N:P in soil were 7.43, 26.11 and 3.44, respectively. In the study area, soil organic carbon and total nitrogen contents were the highest in slope, the lowest in depression, total phosphorus content was the highest in saddle, and showed a decreasing trend from depression land, transition zone and slope land. C:N, C:P and N:P showed the order of slope > depression-slope transition zone > depression > saddle. The results of statistical analysis showed that cation exchange capacity(CEC), pH, water content, bulk density and total calcium content had a good explanation for the stoichiometric characteristics of soil organic carbon, total nitrogen and total phosphorus in karst area. Partial correlation analysis showed that calcium was an important factor affecting organic carbon and total nitrogen. The correlation of soil organic carbon, total nitrogen and total phosphorus stoichiometry with CEC and total cadmium was controlled by calcium. The correlation between available state elements and soil organic carbon, total nitrogen and total phosphorus stoichiometry was less restricted by pH and calcium.【Conclusion】 Soil C, N and P stoichiometry in the study area is affected by geomorphic location, and soil total calcium content is an important influencing factor for soil C, N and P stoichiometry. In agricultural production in the study area, fertilizer with high element availability, especially P, should be applied, and targeted supplement should be made according to the characteristics of fertilizer demand in the growth stage of fruit trees.