Effect of land use patterns on soil nitrogen characteristics in Three-river Headwater Area
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DOI:10.7606/j.issn.1000-7601.2017.03.42
Key Words: land use patterns  alpine meadow  total soil nitrogen  available soil nitrogen  soil ammonium nitrogen  soil nitrate nitrogen
Author NameAffiliation
LI Ya-juan College of Patacultural Science, Gansu Agricultural University
Key Laboratory of Grassland Ecosystem, Ministry of Education
Sino-U.S. Centers for Grazingland Ecosystem Sustainability, Lanzhou, Gansu Province 730070, China 
Wang Ya-ya College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu Province 730020, China 
CAO Guang-min Northwest Plateau Institution of Biology, Chinese Academy of Sciences, Xining, Qinhai Province 810008, China 
LONG Rui-jun College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu Province 730020, China 
YAO Tuo College of Patacultural Science, Gansu Agricultural University
Key Laboratory of Grassland Ecosystem, Ministry of Education
Sino-U.S. Centers for Grazingland Ecosystem Sustainability, Lanzhou, Gansu Province 730070, China 
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Abstract:
      Four land use patterns, i.e., alpine meadow steppe, degraded alpine meadow steppe, degraded alpine steppe and artificial grassland, were selected to study effect of land use patterns on the soil nitrogen characteristics. Soil total nitrogen, available nitrogen, ammonium nitrogen, nitrate nitrogen, total inorganic nitrogen (TIN) and its percentage were determined. The results showed that soil nitrogen content of four land use types were all at a lower level. Soil total and available nitrogen of four land use patterns changed similarly in 0~10 cm soil depth, and the artificial grassland was the highest, the degraded alpine meadow steppe was the lowest. Soil total and available nitrogen in 0~10 cm soil depth for the degraded alpine meadow steppe decreased 52.4% and 76.2% respectively, but those in 10~40 cm soil increased significantly compared with the alpine meadow steppe. The results of soil ammonium and nitrate nitrogen showed that nitrate nitrogen was the main inorganic nitrogen in soil. Degradation caused both ammonium nitrogen and nitrate nitrogen in 0~10 cm soil depth decreasing. Both degradation and artificial planting caused nitrate nitrogen decreased in 0~10 cm soil depth, but increased in 10~20 cm and 20~40 cm soil depth, and there was no significant difference between the two soil depth, while soil nitrate nitrogen decreased in 40~60 cm soil depth. There were no significant differences for both ammonium nitrogen and nitrate nitrogen in 40~60 cm soil among four land use patterns. Therefore, both degradation and artificial planting caused nitrate nitrogen leaching down in soil profile, and the leaching mainly happened in 0~40 cm soil depth. Soil total inorganic nitrogen showed a similar trend with soil nitrate nitrogen. The results of total inorganic nitrogen content and the percentage showed that degradation process increased soil nitrogen mineralization.