Chin J Plant Ecol ›› 2019, Vol. 43 ›› Issue (1): 77-84.DOI: 10.17521/cjpe.2018.0218

• Research Articles • Previous Articles    

Effects of nitrogen and silicon addition on soil nitrogen mineralization in alpine meadows of Qinghai-Xizang Plateau

MOU Jing1,BIN Zhen-Jun2,LI Qiu-Xia1,BU Hai-Yan1,ZHANG Ren-Yi1,XU Dang-Hui1,*()   

  1. 1 School of Life Science, Lanzhou University, State Key Laboratory of Grassland Agro-ecosystems, Lanzhou 730000, China
    2 Guangxi Subtropical Crops Research Institute, Nanning 530001, China
  • Received:2018-09-11 Accepted:2018-10-31 Online:2019-01-20 Published:2019-04-25
  • Contact: XU Dang-Hui
  • Supported by:
    Supported by the National Key R&D Program(2016YFC0501906);the National Natural Science Foundation(30900171);the National Natural Science Foundation(31460162);the National Natural Science Foundation(31600336)

Abstract:

Aims To understand the effects of nitrogen and silicon addition on soil nitrogen mineralization in the context of global climate change.
Methods Nitrogen fertilizer with different concentration were added separately (0, 20, 40, 60 g·m -2, namely CK, N20, N40, N60, respectively) and combined with silicon fertilizer (4 g·m -2 silicic acid, namely Si4). Soil nitrate and ammonium nitrogen contents, net nitrification rate, net ammonification rate as well as net mineralization rate in 0-20, 20-40 and 40-60 cm depth profiles were measured.
Important findings (1) When nitrogen fertilizer was applied alone, soil nitrate and ammonium nitrogen contents under N20, N40, N60 treatments in 0-20 cm soil layer increased by 63.48%, 126.04%, 247.03% and 80.66%, 152.52%, 244.56% respectively, compared with CK. With the increase of soil depth, soil nitrate and ammonium nitrogen both decreased, the nitrate nitrogen content in 20-40 and 40-60 cm soil layers decreased by an average of 53.90%, 76.05% respectively and the ammonium nitrogen content decreased by an average of 48.62%, 68.23% respectively, compared with 0-20 cm soil layer. (2) With the increase of N application, soil net nitrification rate, net ammoniation rate and net mineralization rate all showed an increasing trend. Under the same nitrogen fertilizer concentration, with the increase of soil depth, net nitrification rate, net ammonification rate and net mineralization rate gradually decreased (except for CK). (3) Compared with nitrogen addition alone, soil nitrogen content was significantly improved when nitrogen and silicon fertilizers were both applied, in the 0-20 cm soil layer, the increase ratio of nitrate nitrogen and ammonium nitrogen were 98.78%, 192.62%, 330.16% and 99.96%, 195.82%, 306.32% respectively, compared with CK. This trend was also found in the 20-40 and 40-60 cm soil layers. The results also showed that combined application of nitrogen and silicon had a significant effect on soil nitrogen mineralization. For example, net nitrification rate and net ammonification rate under N60Si4 treatment increased by 35.88% and 27.41% respectively in the 0-20 cm soil layer, compared with nitrogen application alone. The above results showed that compared with the nitrogen addition alone, the application of both nitrogen and silicon can not only increase the nitrogen content in different soil layers, but also promote the mineralization of soil nitrogen and therefore having a certain mitigation effect on atmospheric nitrogen deposition.

Key words: Qinghai-Xizang Plateau, nutrients addition, nitrate nitrogen, ammonium nitrogen, soil nitrogen mineralization, nitrogen deposition