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

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Dynamic of the soil soluble nitrogen and productivity of artificial pasture on the Qingzang Plateau

Pan LIU1,Wen-ying Wang1,Zhou Hua-Kun ZhouXu-feng Mao1,Yan-fang Liu3   

  • Received:2020-08-12 Revised:2021-04-07 Online:2021-04-20 Published:2021-04-14
  • Contact: Wen-ying Wang

Abstract: Aims Nitrogen is the most important limiting factor for artificial pasture. It is unevenly distributed in time and space, and it has differences in form. It is related to planting methods and above-ground net primary productivity (ANPP). In this study, a species artificial pasture of Bromus inermis, Elymus sibiricus, Elymus nutans, Festuca ryloviana, Festuca sinensis, Poa pratensis, Puccinellia tenuiflora and Poa lengdiensis were used as the research object in Tongde, Qinghai Province. The grassland was planted in 2013 without fertilization treatment. It was mowed in the middle of September every year with stubble of 5cm. Methods The soil ammonium nitrogen (NH4+–N), nitrate nitrogen (NO3––N), soluble organic nitrogen (SON) and soluble total nitrogen (STN) were analyzed along the growing season. And ANPP is measured at September each year. Analyze the dynamic change process of soluble nitrogen pool of artificial pasture and the relationship with ANPP. Study findings (1) The average ANPP of artificial grassland planted with 8 pastures were 329.67–794.67 g·m–2. The ANPP of the Elymus nutans was 794.67 g·m–2, which was significantly higher than other treatments. (2) In the second to fourth instar, the soil NO3––N, SON and STN content of artificial pasture decreased significantly with the increase of age level, but the NH4+–N content increased significantly. (3) SON accounted for the highest proportion of soluble nitrogen, accounting for 45.11%–88.76% (0–10 cm) and 47.75%–88.18% (10–20 cm) of STN; the second is NO3--N, accounting for 5.81%–34.85% (0–10 cm) and 6.08%–40.42% (10–20 cm) of STN. NH4+-N is least 3.41%–22.18% (0–10 cm) and 3.09%–19.56% (10–20 cm). (4) The results of non-metric multidimensional scale analysis (NMDS) show that the planting of different pasture have the same effect on soil soluble nitrogen for 0-10 cm with the increase of planting years, while the opposite is the case for 10-20 cm. The effect of pasture on soil soluble nitrogen related to soil depth. (5) Correlation analysis shows that soil SON and STN content are positively correlated with artificial grassland ANPP, and negatively correlated with IN. In summary, nitrogen fertilizer application is one of the key factors to maintain grassland productivity on three to four years old. The above results provide a scientific basis for a more in-depth understanding of the dynamic changes of soil soluble nitrogen and maintaining the productivity and stability of artificial pasture on the Qinghai-Xizang Plateau.

Key words: artificial grassland, soil soluble nitrogen pool, soil inorganic nitrogen pool, Qinghai-Xizang Plateau