Initial responses of grass litter tissue chemistry and N:P stoichiometry to varied N and P input rates and ratios in Inner Mongolia

Xiao Sun, Yue Shen, Michael J. Schuster, Eric B. Searle, Jihui Chen, Gaowen Yang, Yingjun Zhang

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Anthropogenic nitrogen (N) and phosphorus (P) inputs can alter the stoichiometry of senesced plant tissues, a key trait controlling nutrient cycling. However, it is unclear how fertilization rate affects plant litter tissue chemistry under varied N:P supply ratios. In a 2-year study, we investigated the effects of N and P supply rates at three N:P input ratios (4:1, 16:1, and 60:1) on the chemical constitution and N:P stoichiometry of the litter of two grasses: Leymus chinensis and Stipa krylovii. We further evaluated the differential responses of chemical constitution and N:P stoichiometry in leaf and culm litter of L. chinensis. Combined N and P fertilization increased soil acidity and plant-available N, but decreased plant-available P, especially when fertilization occurred at N:P ratio = 60:1. Litter N and P concentrations showed positive response to N and P inputs, and N concentration increased with fertilization rate under N:P ratio = 4:1, but P concentration decreased under N:P ratio = 60:1. Furthermore, we found stronger responses of N and P in L. chinensis and culms than in S. krylovii and leaves. Stoichiometric responses became more positive with increasing N and P fertilization level at each ratio. Nitrogen and P inputs also significantly improved potassium, copper, and sodium concentrations in senesced shoots independent of fertilization rates except for sodium at N:P ratio = 16:1, which had weaker responses in L. chinensis and leaves than in S. krylovii and culms. The effects of N and P inputs on other elements were primarily influenced by species and organs, but were also idiosyncratically affected by input levels at each ratio. These results indicate that decreasing evenness of N and P inputs may have increasingly severe non-linear impacts on nutrient cycling and that these impacts will be greater in L. chinensis-dominated ecosystems compared to those dominated by S. krylovii.

Original languageEnglish (US)
Pages (from-to)114-125
Number of pages12
JournalAgriculture, Ecosystems and Environment
StatePublished - Jan 15 2018

Bibliographical note

Funding Information:
This work was financially supported by National Natural Science Foundation of China (NSFC 600030 , 31501996 ), and Nanjing Agricultural University Foundation ( 6J0026 ).

Publisher Copyright:
© 2017


  • Elemental concentrations
  • Nitrogen and phosphorus addition
  • Senesced leaf and stem
  • Senesced shoot
  • Stoichiometry


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