1.College of Grassland,Resources and Environment,Inner Mongolia Agricultural University,Huhhot;2.Grassland Research Institute of CAAS;3.Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs
National Natural Science Foundation of China Projects (No. 31170435) and the Graduate Education Innovation Program of Inner Mongolia Autonomous Region of China
为解析贝加尔针茅草甸草原土壤有机碳组分对长期氮素添加的响应，于2010年在内蒙古呼伦贝尔市鄂温克旗贝加尔针茅草甸草原设计氮素添加试验，设置8个氮处理，为0（N0）、15（N15）、30（N30）、50（N50）、100（N100）、150（N150）、200（N200）和300（N300） kg·hm-2 ·a-1（以N计），土壤样品于2019年8月采集，进行土壤有机碳及其组分的测定，探究氮素添加10年后土壤有机碳及其组分的变化与驱动因素。结果表明：（1）与对照相比，长期氮素添加下土壤有机碳（SOC）及土壤惰性碳（RP-C）含量无显著变化，土壤活性有机碳（LP-C）的含量增加，其中活性碳组分Ⅰ（LPⅠ-C）增加了0.48%~15.59%，活性碳组分Ⅱ（LPⅡ-C）增加了1.94%~8.41%，易氧化有机碳（EOC）含量无显著变化，可溶性有机碳（DOC）与微生物生物量碳（MBC）含量显著变化，且土壤碳组分整体在N30~N100处理变化敏感；（2）分析土壤有机碳对氮素添加的敏感指数（SI）可知，MBC对长期氮素添加响应更为敏感，可作为本区域有机碳变化的指示碳组分；（3）结构方程模型（SEM）结果显示，长期氮输入条件下土壤碳组分主要受植物生物量与土壤pH的共同调控。综上所述，氮素添加提高了贝加尔针茅草原土壤活性碳组分含量，且土壤有机碳及其组分的变化主要受土壤pH与植物生物量共同调控。
【Objective】This study aimed to analyze the response of soil carbon composition to long-term nitrogen addition in the Stipa baicalensis meadow steppe. 【Method】A nitrogen addition experiment was designed in the meadow steppe of Ewenke Banner, Hulunbuir City, Inner Mongolia in 2010, and 8 nitrogen treatments were set as 0 (N0), 15(N15), 30(N30), 50(N50), 100(N100), 150(N150), 200(N200) and 300(N300) kg·hm-2·a-1(in N). Soil samples were collected in August 2019 and soil organic carbon and its fractions were measured to investigate the changes and drivers of soil organic carbon and its fractions after 10 years of nitrogen addition. 【Results】The results showed that: (1) Compared to the control, soil organic carbon (SOC) content and soil refractory components (RP-C) did not change significantly under long-term nitrogen addition, but activated carbon component I (LPⅠ-C) and II (LPⅡ-C) increased by 0.48%-15.59% and 1.94%-8.41%, respectively. Soil easily oxidized organic carbon (EOC) did not respond, whereas the contents of dissolved organic carbon (DOC) and microbial biomass carbon (MBC) changed significantly. The overall soil carbon composition was more sensitive to N addition at the level of 30, 50 and 100 kg·hm-2 ·a-1; (2) The responses of sensitivity index (SI) of soil organic carbon to nitrogen addition showed that MBC was more sensitive to long-term nitrogen addition, which could be used as an indicator suggesting the changes in organic carbon component in the region; (3) Structural equation modeling (SEM) indicated that soil carbon components were regulated mainly by plant biomass and soil pH under long-term nitrogen conditions. 【Conclusion】Nitrogen addition increases soil active carbon content in Stipa baicalensis and the changes in soil organic carbon and its components are mediated mainly by soil pH and plant biomass.
Wu Zhen-dan, Ma Shang -fei, Lu Jun-yan, Hong Mei, Yang Dianlin. Responses of soil organic carbon components to long-term nitrogen addition in the Stipa baicalensis meadow steppe[J]. Acta Pedologica Sinica,,[In Press]