陇中黄土高原不同土地利用方式下土壤碳氮磷生态化学计量特征

The soil carbon,nitrogen,and phosphorus content, and their ecological stoichiometric characteristics under different land use patterns in the Loess Plateau of Longzhong

摘要:

【目的】 研究陇中黄土高原土壤碳（C）、氮（N）、磷（P）含量及其化学计量学特征对不同土地利用方式的响应。【方法】 选取该地区沙棘林地、苜蓿草地、撂荒裸地和小麦地4种不同土地利用方式土壤，测定土壤C、N、P含量及其理化性质。【结果】 这4种土地利用方式下土壤理化性质差异显著（P＜ 0. 05）。沙棘林地土壤容重最高，小麦地土壤孔隙度和pH值最高，土壤含水量最低；土壤有机碳（SOC） 含量具体表现为苜蓿草地＞沙棘林地＞撂荒裸地＞小麦地，土壤全氮 （TN）含量表现为苜蓿草地＞沙棘林地＞小麦地＞撂荒裸地，土壤全磷（TP）含量则表现为小麦地＞沙棘林地＞苜蓿草地＞撂荒裸地。 在全生长期下，沙棘林地C∶N高出其他3种土地利用方式21.93%~33.70%，且存在显著差异（P＜ 0. 05）；而C∶P及N∶P均表现为苜蓿草地最高；与撂荒裸地相比，苜蓿草地土壤C∶P和N∶P分别提高了 42. 21% 和 42.83%。相关性分析表明，SOC和TN与C∶P和N∶P之间均呈显著正相关关系（P＜ 0. 001），而土壤TP与SOC、TN及化学计量特征之间无显著性。【结论】 苜蓿草地在短期内对土壤养分积累表现出良好的效果，其SOC和TN含量较高，且化学计量学特征表现出较好的平衡，但其是否能够长期稳定积累土壤养分，还需要进一步深入研究。

Abstract:

【Objective】 To investigate the response of soil carbon （C），nitrogen （N），and phosphorus （P） con tents and their stoichiometric characteristics to different land use modes in the Loess Plateau of Longzhong. 【Method】 Soils from four land use modes‐sea buckthorn woodland，alfalfa grassland，abandoned bare land，and wheat land‐ were selected to determine the soil C，N，and P contents and their associated physicochemical properties. 【Result】 The differences in soil physicochemical properties among these four land-use modes were significant （P＜ 0. 05）. The highest soil bulk density was found in sea buckthorn woodland，while wheat farmland had the highest soil porosity and pH，and the lowest soil water content. Soil organic carbon （SOC） content followed the order：alfalfa grassland ＞ sea buckthorn woodland ＞abandoned bare land＞ wheat land. Soil total nitrogen （TN） content ranked as：r alfalfa grassland ＞ sea buckthorn woodland ＞ wheat land ＞abandoned bare land，while soil total phosphorous （TP） content varied from wheat land ＞ sea buckthorn woodland ＞ alfalfa grassland ＞abandoned bare land. During the full-growth period，the C∶N of sea buckthorn woodland was higher than that of the other three land uses by 21. 93%~33. 70%，and the differences were significant （P＜0. 05），while both CP and N∶P were highest in alfalfa grassland. In comparison to abandoned bare land，soil CP and N∶P in alfalfa grassland increase by 42. 21% and 42. 83%，respectively. Correlation analysis revealed a significant positive correlation （P＜0. 001） between SOC and TN with both soil CP and N∶P ratios，while there are no significant correlations between soil TP and SOC，TN，and stoichiometric characteristics.【Conclusion】 Overall，alfalfa grassland demonstrates strong potential for short-term improvement tof soil nutrient accumulation，characterized by high SOC and TN levels and a good balance of stoichio metric characteristics. However，further in‐depth studies are needed to determine whether these benefits can be sus tained over the long term.