植物生态学报 ›› 2019, Vol. 43 ›› Issue (2): 174-184.doi: 10.17521/cjpe.2018.0245

• 研究论文 • 上一篇    

不同形态和水平的氮添加对内蒙古草甸草原土壤净氮矿化潜力的影响

李阳1,2,徐小惠1,2,孙伟3,申颜1,4,任婷婷1,2,黄建辉1,2,王常慧1,*()   

  1. 1 中国科学院植物研究所植被与环境变化国家重点实验室, 北京 100093
    2 中国科学院大学, 北京 100049
    3 东北师范大学植被生态学教育部重点实验室, 长春 130024
    4 山西农业大学动物科技学院, 山西太谷 030801
  • 收稿日期:2018-10-05 接受日期:2019-01-31 出版日期:2019-02-20 发布日期:2019-06-04
  • 通讯作者: 王常慧 E-mail:wangch@ibcas.ac.cn
  • 基金资助:
    国家重点研发计划(2016YFC0500703);国家自然科学基金(31572452);国家自然科学基金(41573063)

Effects of different forms and levels of N additions on soil potential net N mineralization rate in meadow steppe, Nei Mongol, China

LI Yang1,2,XU Xiao-Hui1,2,SUN Wei3,SHEN Yan1,4,REN Ting-Ting1,2,HUANG Jian-Hui1,2,WANG Chang-Hui1,*()   

  1. 1 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2 University of Chinese Academy of Sciences, Beijing 100049, China
    3 Key Laboratory of Vegetation Ecology, Ministry of Education, Northeast Normal University, Changchun 130024, China
    4 College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Taigu, Shanxi 030801, China
  • Received:2018-10-05 Accepted:2019-01-31 Online:2019-02-20 Published:2019-06-04
  • Contact: WANG Chang-Hui E-mail:wangch@ibcas.ac.cn
  • Supported by:
    Supported by National Key R&D Program of China(2016YFC0500703);the National Natural Science Foundation of China(31572452);the National Natural Science Foundation of China(41573063)

摘要:

由全球变化和工农业生产引发的大气氮沉降增加已经对生态系统结构和功能产生了不可忽视的影响, 但是氮沉降的组成成分存在多种形态, 不同形态的氮对生态系统的结构与功能的影响是否有差异目前还不清楚。因此, 该研究选择内蒙古草甸草原开展不同形态和不同水平的外源氮添加试验, 每年添加5种不同形态的氮肥, 包括: 尿素、碳酸氢铵、硝酸铵、硫酸铵、缓释尿素, 添加量分别为: 0 (N0)、2 (N2)、5 (N5)、10 (N10)、20 (N20)及50 (N50) g·m -2·a -1, 均为纯氮添加量。通过野外原位取土、室内控制温度和水分(25 ℃和60%田间持水量)的培养试验测定土壤净氮矿化(mg·kg -1·h -1)潜力、土壤微生物呼吸(μg·g -1·h -1)潜力、土壤微生物生物量碳(氮)(mg·kg -1)的潜力以及土壤碳(g·kg -1)、氮(g·kg -1)、磷(g·kg -1)含量等指标, 研究添加不同形态和不同水平的氮对土壤净氮矿化潜力的影响。试验结果表明: (1)短期内不同形态、不同水平的氮添加改变了土壤中无机氮的含量、铵态氮和硝态氮的累积量, 并且表现出铵态氮肥的促进作用比硝态氮肥更加显著, 铵态氮的累积显著提高了土壤净氮矿化潜力, 短期铵态氮和硝态氮的累积可增加微生物和植物对有效氮的快速固持; (2)不同形态、不同水平氮添加导致土壤微生物活性发生改变, 包括土壤微生物生物量碳(MBC)含量、微生物生物量氮(MBN)含量及其碳氮比(MBC:MBN), 并且在低水平氮添加下显著增强土壤微生物的呼吸速率, 高水平氮添加显著降低微生物呼吸速率和呼吸熵; (3)不同形态、不同水平氮添加短期内对土壤含水量、土壤有机碳含量、土壤全磷含量、土壤全氮含量无显著影响, 但是高水平氮添加不仅提高了速效磷的含量, 而且导致土壤迅速酸化。室内培养净氮矿化潜力的结果进一步验证了内蒙古草甸草原受氮限制, 添加中低水平的氮可以通过提高土壤微生物的活性而增加该地区草原土壤的净氮矿化潜力, 从而提高草地生产力。

关键词: 氮添加, 净氮矿化潜力, 土壤微生物活性, 草甸草原

Abstract:
Aims The increase of atmospheric nitrogen (N) deposition caused by global change and industrial and agricultural production has had an important impact on the structure and function of ecosystems. There are many forms in composition of atmospheric N deposition. However, it is not clear whether there are differences in the effects of N deposition forms on structure and function of the ecosystems. Here our objective was to characterize the effects of different forms and levels of N addition on soil net N mineralization potential of steppe ecosystem in the Nei Mongol.
Methods A N addition experiment was carried out in the meadow steppe in Nei Mongol using five different N fertilizers, including CO(NH2)2, NH4HCO3, NH4NO3, (NH4)2SO4, and slow-release urea separately since 2014. There were six N addition levels with 0 (N0), 2 (N2), 5 (N5), 10 (N10), 20 (N20) and 50 (N50) g·m -2·a -1. Fresh soil samples from all treatments were taken and all roots were removed in July 2016. Then these soil samples were incubated for 24 h at 25 °C with 60% field water capacity. The potential of net N mineralization and nitrification rates and the potential of soil microbial respiration (MR), soil physical and chemical properties, soil microbial biomass carbon (MBC) and N (MBN) contents were measured, respectively.
Important findings The results showed that: (1) different forms and levels of N addition significantly increased soil inorganic N content and potential net N mineralization and nitrification rates. The N20 treatment had the highest soil inorganic N content and net N mineralization rate, however the highest soil net nitrification rate was found under N50 treatment; (2) different forms and levels of N addition significantly increased MBC and MBN contents and decreased the microbial metabolic quotient (qCO2). Lower N addition (N2) enhanced MR, but medium and higher N addition (N20, N50) restrained the MR; (3) different forms and levels of N addition significantly reduced the soil pH value, but significantly increased the available phosphorus content. No effects were found in soil water content, total phosphorus, total N and soil organic carbon contents, separately. The results verified that soil available N was the limited factor affecting plant productivity in meadow steppe in Nei Mongol steppe. No matter what type of N fertilizer can increase the activity of soil microorganism and the potential net N mineralization rate of the meadow steppe in this area.

Key words: nitrogen addition, potential net nitrogen mineralization, soil microbial activity, meadow steppe