关键词: 初霜, 初霜, 多模型离散覆盖, 灰关联度, 白化预测值, 动态灰预测

Abstract: Analyze of the soil available phosphorus and available potassium in a 6.0 hectare Populus tomentosa planted land in Guanxian county of Shandong province was aimed to benefit test arrangement of Populus tomentosa planted land, the site specific nutrient management and determining rational sampling number.To have a better understanding the available phosphorus and available potassium status grid sampling method with grid size (50m×50m) was used. Each grid was subdivided into three layers(0~20㎝,20~40㎝, 40~60㎝). Results showed: Available nutrient content was a lower level , which was decreased with the soil depth, and the ranges of available phosphorus was 1.32~1.89mg?kg-1, the population mean was 1.51±0.09mg?kg-1, and the contents of three layers was 1.66±0.15mg?kg-1, 1.44±0.07mg?kg-1, 1.44±0.06mg?kg-1, respectively. The ranges of available potassium was 23~78mg?kg-1, the population mean was 46.95mg?kg-1, and the contents of three layers was 63.29±9.69mg?kg-1, 43.38±8.35mg?kg-1, 34.17±6.96mg?kg-1, respectively. The Coefficient of Variance of the available phosphorus was 9%, 5%, 4% in three layers, respectively, which were weak variability. And available potassium was 15%, 19%, 20% in three layers, respectively, which were moderate variability. Rational sampling number was related to coefficient of variation and sampling precision. The value of available phosphorus changed little both in the horizontal direction and vertical direction, and the coefficient of variance of available potassium increased at first and then decreased from west to east, but ascended and descended , varied complicatedly from north to south.