Li Zi-Yang, Chen Lu, Zhao Peng, Zhou Ming-Hua, Zheng Jing, Zhu Bo
Key Laboratory of Mountain Surface Process and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Huan Jing Ke Xue. 2024 Jan 8;45(1):343-353. doi: 10.13227/j.hjkx.202302013.
Since the 1990s, a large area of sloping farmland in a purple soil hilly region of southwest China was converted into an orchard to prevent soil erosion, increase soil fertility, and elevate economic benefits for farmers. In order to explore the spatial distribution of soil carbon (C) and nitrogen (N) fractions on the slope of returning arable lands to citrus orchards in purple soil hilly areas, a soil sampling event was carried out in a citrus orchard at the Yanting Agro-ecological Experimental Station of Purple Soil, Chinese Academy of Sciences, to examine the differences in soil C and N fractions and their influencing factors. The results showed that the slope position had significant effects on the contents of soil total nitrogen (TN), nitrate nitrogen (NO-N), and dissolved organic carbon (DOC) ( < 0.05), but the effects were not obvious regarding the total organic carbon (SOC) and ammonia nitrogen (NH-N) of the soil ( > 0.05). For topsoil (0-30 cm), the variation trend of soil NO-N content along the slope was upper slope < middle slope < lower slope, whereas the TN and DOC contents along the slope exhibited the trend of upper slope > middle slope > lower slope. The contents of soil C and N in each slope position generally showed a downward trend with increasing soil depth (0-30 cm). The contents of soil TN, SOC, NO-N, and DOC were significantly affected by soil depth ( < 0.05). The TN storage (0-30 cm) significantly decreased from the top to the bottom within the soil slope, with a value of 2.37, 1.89, and 1.62 t·hm (reported as N) for the upper slope, middle slope, and lower slope, respectively. There was no significant difference in SOC reserves along the slope, with a range from 56.12 to 58.48 t·hm (reported as C). Our results provide scientific basis for understanding the spatial distribution of soil nutrients of the restored farmland in purple soil hilly areas. Our research suggests that the spatial distribution of soil carbon and nitrogen storage should not be ignored when predicting the response of soil nutrients to land use change.
自20世纪90年代以来，中国西南紫色土丘陵区的大片坡耕地被改造成果园，以防止土壤侵蚀、提高土壤肥力并增加农民经济效益。为了探究紫色土丘陵区坡地退耕还柑橘果园土壤碳（C）和氮（N）组分的空间分布，在中国科学院紫色土盐亭农业生态试验站的一个柑橘果园进行了土壤采样，以研究土壤C和N组分的差异及其影响因素。结果表明，坡位对土壤全氮（TN）、硝态氮（NO₃-N）和溶解性有机碳（DOC）含量有显著影响（P＜0.05），但对土壤有机碳（SOC）和铵态氮（NH₄-N）的影响不明显（P＞0.05）。对于表层土壤（0-30厘米），土壤NO₃-N含量沿坡面的变化趋势为上坡＜中坡＜下坡，而TN和DOC含量沿坡面呈上坡＞中坡＞下坡的趋势。各坡位土壤C和N含量总体上随土壤深度（0-30厘米）增加呈下降趋势。土壤TN、SOC、NO₃-N和DOC含量受土壤深度显著影响（P＜0.05）。土壤坡面自上而下TN储量（0-30厘米）显著降低，上坡、中坡和下坡的TN储量分别为2.37、1.89和1.62吨·公顷（以N计）。坡面SOC储量无显著差异，范围为56.12至58.48吨·公顷（以C计）。我们的研究结果为理解紫色土丘陵区恢复农田土壤养分的空间分布提供了科学依据。我们的研究表明，在预测土壤养分对土地利用变化的响应时，不应忽视土壤碳氮储量的空间分布。
