Chin J Plant Ecol ›› 2021, Vol. 45 ›› Issue (5): 562-572.DOI: 10.17521/cjpe.2020.0279

Special Issue: 青藏高原植物生态学:植物-土壤-微生物

• Research Articles • Previous Articles    

Dynamics of soil soluble nitrogen and plant productivity in artificial pastures on the Qingzang Plateau

LIU Pan1,3, WANG Wen-Ying3,*(), ZHOU Hua-Kun2, MAO Xu-Feng1, LIU Yan-Fang3   

  1. 1College of Geography Sciences, Qinghai Normal University, Xining 810008, China
    2Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
    3College of Life Sciences, Qinghai Normal University, Xining 810008, China
  • Received:2020-08-12 Accepted:2020-11-22 Online:2021-05-20 Published:2021-04-14
  • Contact: WANG Wen-Ying
  • Supported by:
    the National Natural Science Foundation of China(41761107);the Second Tibetan Plateau Scientific Expedition and Research (STEP) Program(2019QZKK0302)


Aims Nitrogen is the most limiting factor to artificial pastures. It is distributed unevenly in time and space, and has different forms, which are correlated with cultivation approaches and above-ground net primary productivity (ANPP). This study investigated the dynamics of soil nitrogen and productivity in artificial pastures of Bromus inermis, Elymus sibiricus, E. nutans, Festuca ryloviana, F. sinensis, Poa pratensis var. anceps ‘Qinghai’, P. crymophila and Puccinellia tenuiflora in pure species cultivations in the Tongde farm of Qinghai Province. The dynamics of soil soluble nitrogen pools in each artificial pasture type and their relationships with ANPP were examined.
Methods The pastures were planted in 2013 without fertilizer application, and mowed to the level with 5 cm stubble in mid-September every year. The soil ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N), soluble organic nitrogen (SON) and soluble total nitrogen (STN) content were measured during growing seasons. ANPP was determined in September each year.
Important findings (1) The average ANPP across the eight pasture types ranged between 329.67-794.67 g·m -2, with the ANPP of 794.67 g·m -2 for the E. nutans significantly higher than other pasture types. (2) From the second to fourth year following planting, the content of soil NO3 --N, SON and STN significantly decreased, but that of the NH4+-N significantly increased. (3) SON accounted for the highest proportion of STN, varying between 45.11%-88.76% in the 0-10 cm soil layer and 47.75%-88.18% in the 10-20 cm soil layer, followed by NO3--N in ranges of 5.81%-34.85% (0-10 cm) and 6.08%-40.42% (10-20 cm), respectively; NH4+-N had the least proportion at 3.41%-22.18% (0-10 cm) and 3.09%-19.56% (10-20 cm), respectively. (4) The non-metric multidimensional scale analysis (NMDS) shows that the temporal effect on soil soluble nitrogen content by different pasture types diverged for the 0-10 cm soil layer, but converged for the 10-20 cm soil layer, and that the effect of pasture types on soil soluble nitrogen content was related to soil depth. (5) Soil SON and STN contents were positively correlated with ANPP, and negatively with inorganic nitrogen (IN) content. In summary, nitrogen fertilizer application is one of the key factors for maintaining the productivity of artificial pasture from three to four years. The above results provide a scientific basis for a more in-depth understanding of the dynamics of soil soluble nitrogen and the maintenance of productivity and stability of artificial pastures on the Qingzang Plateau.

Key words: artificial pasture, soil soluble nitrogen pool, soil inorganic nitrogen pool, Qingzang Plateau