2.1 Experimental site
The field experiment of this study has been carried out for 10 years
since Da‘an Sodic Land Experiment Station (DASLES), Chinese Academy of
Sciences (CAS)
(45°35′58″~45°36′28″N,123°50′27″~123°51′31″E),
which is located in Da‘an city of Jilin Province of China. The DASLES is
a typical saline degraded grassland ecosystem located in the Western of
Songnen Plain, . The area is semi-arid with a temperate continental
climate. The annual mean temperature
is 4~, the annual mean precipitation is
350~ in the area. While evaporation is about , which is
4~5 times of the precipitation.
The original field experiment was conducted in two different kinds of
saline-sodic grassland: moderately saline-sodic grassland (MSSL), with
soil pH 8.94 and ECe 5.7 dS m–1, and severely
saline-sodic grassland (SSSL), with soil pH 9.80 and ECe 8.8 dS
m–1. This study was only carried out in MSSL, for
other basic chemical characteristics of grassland soils, please refer to
our previous studies (Huang et al. , 2015 & 2019).