通过土样测定,利用统计分析方法系统研究乌兰布和沙区绿洲农地钾素的特征、时间动态及其对土壤性质的响应.结果显示,变异系数速效钾最高(42.49％),全钾最低(13.66％),各形态钾素整体分布不均；绝大多数钾素含量表现为表层低于下层且差异不显著.籽瓜、油葵、番茄和紫花苜蓿地表层速效钾平均含量属中等水平,而玉米、花葵和对照地属缺钾水平；若以有效性钾含量判定则研究区钾素供给充足.表层缓效钾含量均属中上水平,缓效钾平均转化率为22.02％,其中,紫花苜蓿地最高(24.40％),籽瓜地最低(18.91％).表层全钾平均含量为19.20 g/kg,其中,速效钾占0.55％,缓效钾占2.85％,矿物钾占96.60％.在时间动态上,速效钾、有效性钾和缓效钾含量呈先增后降的二次曲线模型,峰值临界年限分别为21、18和17 a.全钾、矿物钾、有效性钾、缓效钾、碱解氮、物理性粘粒、CaCO3和阳离子交换量(CEC)通过直接和间接效应综合影响速效钾含量,可解释总变异量的78.9％.%Through measuring soil samples of different oasis farmlands in the Ulanbuh sandy areas, using statistical analytical method, the characteristics, evolution process and influence factors (soil properties) of soil potassium were studied systematically. The results showed that the variation coefficient of readily available potassium(RAK) was the highest(42. 49%) and that of total potassium(TK) was the lowest(13. 66%), and which meant that the contents of various potassium were overall uneven distribution. The overwhelming majority of various potassium contents of topsoil (0 - 20 cm) was lower than the subsoil (20 - 40 cm) and there had no significant difference between vertical layers. RAK average content of topsoil belonged to "medium" level in farmlands of seed watermelon, oil sunflower, tomato and alfalfa, and lacking in farmlands of corn, sunflower and control. Judging by the content of available potassium (AK), and potassium supply was abundant in study areas. Average content of slowly available potassium (SAK) in topsoil belonged to "above average" level in all farmlands, and average conversion of SAK was 22. 02% , among them, the average conversion of farmland in alfalfa and seed watermelon was the highest(24. 40%) and lowest(18. 91%) respectively. TK average content of topsoil was 19. 20g/kg, among them, the proportion of RAK, SAK and mineral potassium (MK) took up respectively 0. 55% , 2. 85% and 96. 60%. The evolution processes of RAK, AK and SAK with time were simulated quadratic curve model, which increased firstly and decreased subsequently over time, the peak critical time was respectively about 21 years, 18 years and 17 years. The content of RAK was influenced directly and indirectly by TK, MK, AK, RAK, SAK, available N, physical clay, CaCO3 and CEC, and they could explain significantly 78. 9% of the total variance of them.
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