摘要 基于乌兰布和绿洲区林地和农地，系统研究了土壤各形态钾素特征并进行土壤钾素综合评价。结果显示，地类间的速效钾、有效性钾和缓效钾变异系数高于30%，含量高出对照1.1～2.9倍，而矿物钾和全钾差异小（<15%），含量稍高于对照。大多地类速效钾富足，部分林地和玉米、花葵地已缺钾，钾素重要潜源缓效钾平均转化率高达22.7%。6个评价指标对土壤钾素指数（SKI）贡献高达92%，排序依次为有效钾因子（有效性钾>速效钾>缓效钾）、储量钾因子（矿物钾=全钾）和缓效钾转化率;82%的SKI>0.5，51%的SKI>0.6，综合供钾能力较强，但部分农地需少量补钾。建议研究区林地种植二白杨、小美旱杨、柽柳及沙枣、柠条、沙棘等固氮植物（花棒除外），农地种植低耗经济作物和苜蓿等固氮牧草，也适合在其他干湿交替明显的干旱灌区推广。

关键词 乌兰布和绿洲区;土地利用;土壤钾素;综合评价

中图分类号 X825 文献标识码 A 文章编号 0517-6611（2021）17-0140-04

doi：10.3969/j.issn.0517-6611.2021.17.037

Abstract Based on forestland and farmland in Ulanbuh oasis areas， the characteristics of various soil kaliums were studied systematically and comprehensive evaluation of them were carried out. The results showed that the variation coefficients of available kalium （AK）， readily available kalium （RAK） and slow available kalimu （SAK） were all above 30% respectively， and their contents were 1.1-2.9 times of the control sample， the difference of mineral kalium （MK） and total kalium （TK） among soil sample were all small （<15%） respectively， and the contents of both were slightly more than the control samples. AK contents of most land was rich， and lacking in some of the forestland， corn land and sunflower land. The average conversion of SAK （important potential source of RAK） was 22.7%. The six evaluation indexes contributed up to 92% to soil kalium index （SKI）， and ranked as follows： available kalium factor （RAK>AK>SAK）， reserve kalium factor （MK=TK） and the conversion of SAK. The proportion of SKI>0.5 and SKI>0.6 was 82% and 51% respectively. The comprehensive deliverability of kalium was strong， but some farmland needed a small supplement of kalium. In study area， it was recommended to plant Populus gansuensis C.， Populus simonii×（Populus pyramidalis+Salix matsudana） cv.， Tamarix chinensis Lour and nitrogen fixation plants （except for Hedysarum scoparium Fisch.） as Elaeagnus angustifolia L.， Caragana korshinskii Kom.and Hippophae rhamnoisdes L. in forestland， to plant low-consumption cash crops and nitrogen fixation grasses such as alfalfa in farmland， these recommendations will be also suitable for other arid irrigated areas with obvious alternations of dry and wet.

Key words Ulanbuh oasis areas;Land utilization;Soil kaliums;Comprehensive evaluation

地處华北和西北结合部的乌兰布和沙区是我国典型的生态脆弱农牧交错带和沙尘暴主要尘源地之一，因乌兰布和沙区东南缘毗邻黄河而给植被恢复重建、改善生态环境、发展沙区农业创造了便利条件，经过30多年的植被恢复建设和土地合理开发，乌兰布和沙区东南缘现已形成了乔灌草结合、农灌配套、防护林网密集的人工绿洲6 000 hm2，绿洲体系的形成逐渐改良了土壤结构状况，有效减少尘源物质（粒径小于100 μm）而大大降低沙尘暴的发生频率，也基本解决了风沙危害限制农业可持续发展的瓶颈问题。钾作为植物吸收最多且土壤中含量最高的大量营养元素之一，钾素形态的相互转化在共同维持动态平衡的基础上对植物的有效性发挥着不同的重要作用，绿洲体系的建成不但改善了土壤微生物区系和土壤质量，势必也影响土壤各形态钾素的动态平衡、植物有效性和土壤供钾能力[1-3]。我国北方普遍……