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Acta Prataculturae Sinica ›› 2015, Vol. 24 ›› Issue (10): 12-21.DOI: 10.11686/cyxb2015154

• Orginal Article • Previous Articles     Next Articles

Effects of nitrogen addition on the physical properties of soil in an alpine meadow on the eastern Qinghai-Tibetan Plateau

LIU Xiao-Dong1, 2, 3, YIN Guo-Li1, 2, WU Jun4, CHEN Jian-Gang1, 2, MA Long-Xi5, SHI Shang-Li1, 2, *   

  1. 1.College of Grassland Science, Gansu Agricultural University, Lanzhou 730070, China;
    2.Key Ecosystem Laboratory of the Ministry of Education, Pratacultural Engineering Laboratory of Gansu Province, Sino-US Center for Grazingland Ecosystem Sustainability, Lanzhou 730070, China;
    3.Tianshui Animal Husbandry Technique Extension Station, Tianshui 741000, China;
    4.College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou 730070, China;
    5. Grassland station, Xiahe county, Xiahe 747100, China
  • Online:2015-10-20 Published:2015-10-20

Abstract: A 3-year study was conducted from 2012 to 2014 to determine the effects of nitrogen (N) addition on the physical properties of soil in an alpine meadow in Xiahe County on the eastern Qinghai-Tibetan Plateau. The four treatments were as follows: CK (control, no N addition), LN (low N, 50 kg N/ha), MN (medium N, 100 kg N/ha), and HN (high N, 150 kg N/ha). Each N-addition treatment had three replicates of 54 m2 (6 m×9 m), with a 1.5 m isolation band between adjacent plots. Analyses of soil bulk density, soil porosity, soil compaction, and soil aggregates showed that MN and HN treatments reduced soil bulk density and soil compaction, increased soil porosity and non-capillary porosity, and maximized water-holding capacity in the 0-10 cm soil layer. In the 20-30 cm soil layer, compared with CK, all N-addition treatments showed higher soil bulk density and soil compaction, reduced soil porosity, and maximized water-holding capacity. In terms of the effect of N addition on the stability of soil aggregates in the 0-30 cm soil layer, the LN, MN, and HN treatments dramatically increased the macro-aggregate content (≥0.25 mm) and MWD (mean weight diameter), with the MN treatment having the strongest effect. Compared with CK, LN and MN dramatically improved the water-stable aggregate content. All of the N-addition treatments significantly promoted soil aggregation and increased the MWD of aggregates. The results indicated that N addition could effectively prevent soil erosion, and hence, control the loss of water and soil nutrients. The MN and HN treatments significantly increased the aboveground biomass in the grassland, while underground biomass was increased in the MN treatment and decreased in the HN treatment. The results of this study showed that the MN treatment was the most beneficial treatment in terms of improving soil properties. This treatment increased soil bulk density, reduced soil porosity, and increased soil compaction, increased the content of ≥0.25 mm soil aggregates and improved aggregate stability, and increased both the aboveground and underground biomass of plants in the grassland.