Evaluation of soil nutrients status of Lycium barbarrum orchard in Qaidam Basin

In order to know the soil nutrients status, investigation and soil sample determination were carried out in the Lycium barbarrum orchard of Qaidam Basin. Four sites were selected as the study area, they were Delingha, Dulan,Golmud and Wulan, respectively. The results indicated that the organic matter content was highest in Wulan county, 50.0% sample distributed in the range of 20~30 g/kg. It was found that the content of soil available nitrogen in Delingha city was the top in Qaidam Basin, 30.9 % sample distributed in the range of above 200 mg/kg. Compared with the 2nd national soil survey data, the soil available phosphorus content in whole Qaidam Basin was larger. In Delingha city and Wulan County,the content of available potassium in L. barbarrum orchard was ample, 50.6 % and 75.0 % sample distributed in the range of above 200 mg/kg, respectively. In total area, the soil salinity was lowest in Dulan County, 94.4%sample distributed in the range of under 5 mg/kg. So it should be noted the large amount of salinity in some site of Qaidam Basin was likely to cause the secondary salinization. The soil pH values of L. barbarrum orchard in Qaidam Basin varied from 7.6 to 8.6 among 184 soil samples袁the average value was 8.4，no significant difference was found among four sites. In conclusion，Wulan county and Delingha city 's soil integrate fertility was the highest in all sites, followed by Golmu city and Dulan County. So the suitable fertilization strategy was recommended based on the characteristics of soil fertility classes and the fertilizer requirement in different growth periods of L. barbarrum.