水曲柳人工林与天然林土壤中不同形态钾素的含量与分布

Content and distribution of different potassium forms in soil of Fraxinus mandshurica plantation and natural forest

【目的】对比分析水曲柳人工林和水曲柳天然林间土壤各形态钾素含量的差异、非交换性钾转换量、转换率差异和各形态钾素层化比率的差异,为水曲柳人工林土壤肥力诊断、施肥和林分科学培育提供理论依据。【方法】以东北林业大学森林培育实验站水曲柳天然林隔带采伐后营造的红皮云杉-水曲柳混交林、红松-水曲柳混交林、长白落叶松-水曲柳混交林和水曲柳人工纯林为研究对象,原有以水曲柳和胡桃楸为主的天然混交林为对照。对土壤样品使用去离子水浸提土壤水溶性钾,0.5 mol·L^(-1)中性醋酸镁溶液浸提土壤非特殊吸附性钾,1 mol·L^(-1)中性醋酸铵溶液浸提土壤特殊吸附性钾,1 mol·L^(-1)热硝酸浸提土壤非交换性钾,2 mol·L^(-1)冷硝酸浸提土壤有效钾。采用火焰光度计测定各形态钾含量,氢氧化钠熔融-火焰光度法测定全钾含量,并分析土壤非交换性钾转换和各形态钾素的层化状况。【结果】1)4种类型水曲柳人工林土壤水溶性钾、非特殊吸附性钾、特殊吸附性钾、非交换性钾含量均显著低于水曲柳天然林,且以红皮云杉-水曲柳混交林最小,长白落叶松-水曲柳混交林最大(P<0.05)。2)4种类型水曲柳人工林各土层非交换性钾含量均为中等水平,而水曲柳天然林0~20 cm土层则为丰富水平。在0~10和20~30 cm土层,红皮云杉-水曲柳混交林非交换性钾转换量和转换率均为最高,10~20 cm土层长白落叶松-水曲柳混交林非交换性钾转换量和转换率均为最高(P<0.05)。3)4种类型水曲柳人工林和水曲柳天然林土壤速效形态钾和有效形态钾均出现了明显的表聚和层化现象。水曲柳人工林中,土壤速效形态钾以长白落叶松-水曲柳混交林表聚和层化程度最大(P<0.05)。【结论】水曲柳人工林土壤较水曲柳天然林土壤有效钾素含量发生了较大退化,应积极合理地对水曲柳人工林土壤施用钾肥,以改善土壤质量并促进林分生长。

【Objective】Comparing the difference of water soluble potassium,nonspecific adsorption potassium,special adsorption potassium,non-exchangeable potassium,mineral potassium,conversion content and conversion rate of non-exchangeable potassium,and layer ratio of different potassium forms in the soilbetween different artificial and natural Fraxinus mandshurica forests.Providing theoretical basis for the soil fertility diagnosis,fertilization and cultivation of Fraxinus mandshurica forest.【Method】Taking Picea koraiensis-Fraxinus mandshurica mixed plantation,Pinus koraiensis-Fraxinus mandshurica mixed plantation,Larix olgensis-Fraxinus mandshurica mixed plantation and pure Fraxinus mandshurica plantation,which were planted on the natural forest clear cutting land in the forest cultivation experiment station of Northeast Forestry University as materials,contrast to the original natural Fraxinus mandshurica mixed forest,contents of water soluble potassium,nonspecific adsorption potassium,special adsorption potassium,non-exchangeable potassium and effective potassium in the soil samples were measured by use of flame photometer after leached by deionized water,0.5 mol·L^(-1)neutral magnesium acetate solution,1 mol·L^(-1)neutral ammonium acetate solution,1 mol·L^(-1)hot nitric acid and 2 mol·L^(-1)cold nitrate.Total potassium content was measured by sodium hydroxide melting-flame photometry.The conversion of non-exchangeable potassium and layer ratio of different forms potassium in the soil of different forests types were analyzed.【Result】1)Content of water soluble potassium,nonspecific adsorption potassium,special adsorption potassium and non-exchangeable potassium in the soil of four types of Fraxinus mandshurica plantations were significantly lower than that of Fraxinus mandshurica natural forest,which was the lowest in Picea koraiensis-Fraxinus mandshurica mixed plantation and highest in Larix olgensis-Fraxinus mandshurica mixed plantation(P<0.05).2)Content of non-exchangeable potassium in the soil of four types of Fraxinus mandshurica plantation was at the medium level,while it was rich level at 0-20 cm layer of natural forest.Conversion contents and conversion rates of non-exchangeable potassium at 0-10 cm and 20-30 cm soil layer was the highest in Picea koraiensis-Fraxinus mandshurica mixed plantation,while in 10-20 cm soil layer it was the highest in Larix olgensis-Fraxinus mandshurica mixed plantation(P<0.05).3)There was obvious upper concentration and stratification phenomena of the available potassium components and effective potassium components in the soil of Fraxinus mandshurica plantation and natural Fraxinus mandshurica forest,the degree of upper concentration and stratification of available potassium components was the largest in Larix olgensis-Fraxinus mandshurica mixed plantation among four types of Fraxinus mandshurica plantations(P<0.05).【Conclusion】Great degradation of the soil available potassium content had taken place after changing natural Fraxinus mandshurica forest to artificial Fraxinus mandshurica plantation.The contents of different potassium forms and their distributions in the soil indicate that potassium fertilizer should be positive and reasonable used to the soil of Fraxinus mandshurica plantation,in order to improve soil quality and promote stand growth.