The Taklimakan Desert is one of the most arid areas in the world, where the average annual precipitation is less than 50 mm. The survival of natural plants in such an extremely arid environment is a result of evolutionary adaptation to the extreme environment. In the arid ecosystem of the Taklimakan Desert, water is one of the major limiting factors for the sustainable development of plant species. However, water scarcity is a serious problem in this region. Thus, lower quality-water, such as saline groundwater, is widely used to overcome water shortage.

Saline groundwater typically contains solutes of varying concentrations. The utilization of saline groundwater may affect soil properties and plant growth. To determine the effects of saline water irrigation on Aeolian sandy soil development and clarify how the soil salinity induced by saline water irrigation impacts plant growth in the Taklimakan Desert, Dr. LI Congjuan et al. conducted field investigation in the Taklimakan Desert Highway shelterbelt in September 2012. They selected seven soil sampling sites with different degrees of groundwater salinity to investigate the effects of different salinity irrigations on soil properties. Moreover, three plant species (i.e. Haloxylon, Tamarix and Calligonum) were selected to evaluate the effects of salt irrigation on the root distribution of plants.

Within the upper soil layers, salinity water irrigation on the shelterbelt resulted in the soil salt accumulation and significant nutrients increasing. Salinity water irrigation had little influence on soil pH, soil organic matter (SOC), total nitrogen (TN) and total phosphorus (TP) but significant influence on soil salt content. SOC, TN and TP increased under lower levels of salinity (3.6–15.5 g/L) in the irrigated groundwater, while SOC and TP decreased under higher levels of salinity (>15.5 g/L). Among the three plant species, Tamarix had the deepest main root system extended to 200 cm, while the other two species only extended to 150 cm. More than 87% of the biomass of the lateral roots was present in the 20–80 cm soil depths for the three species. No active absorbing roots were found in the upper 0–10 cm soil depths with higher soil salt contents.

These results indicated that saline water probably does not influence the normal growth of plants in a desert environment where saline groundwater is the sole water resource for plants. Furthermore, saline water irrigation within artificial shelterbelts is beneficial for the accumulation of soil nutrients.

The study was published in Soil & Tillage Research in March 2015.

Contact:
Dr. LI Congjuan
Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences
E-mail: li_congjuan@163.com