Soil nutrients content and grain size fraction of aeolian sandy land in the Shannan Wide Valley of the Yarlung Zangbo River, China

Abstract

We conducted a case study to examine the soil nutrients content and grain size fraction of different aeolian sandy land types in the Shannan wide valley area, middle reaches of the Yarlung Zangbo River by choosing moving sandy land, flat sandy gravel land, semi鄄fixed sandy land, fixed sandy land and sandy land on flood plain as sample plots. The mechanism how aeolian sand movement affects soil grain size fraction and nutrients content of aeolian sandy land was discussed based on field sand movement observation and wind velocity and direction data from 1980 to 2006 from the Lhasa Airport meteorological station. The results showed that 1) The soil pH value of aeolian sandy land in the study area was neutral, alkaline or strong alkaline, and soil organic matter ( SOM) and total nitrogen ( TN) content were rather low, whereas total phosphorus ( TP) and total potassium ( TK) were very high. The soil grain size fraction followed the order of sand content (53. 83% -95. 93% ) > silt content (3. 3% -40. 5% ) > clay content (0. 77% -5. 68% ) , and the clay and silt content both presented rather low. 2) The clay and silt content was highest in sandy land on flood plain (4. 02% and 27. 95% , respectively) , whereas that was lowest in semi鄄fixed sandy land (1. 35% and 5. 27% , respectively) . The clay