成都平原不同土地利用方式对土壤剖面钾素分布的影响

Effects of different land use patterns on soil potassium distribution in Chengdu Plain, China

为探索快速城市化背景下土地利用方式变化对土壤剖面钾素变化的影响,本研究选取成都平原4种典型土地利用方式(稻-麦、稻-蔬、稻-油和园林),基于187个土壤剖面数据,分析了不同土地利用方式下土壤剖面速效钾、缓效钾、矿物钾和全钾4种不同形态钾的含量特征及相互关系.结果表明:从表层土壤来看,相较传统轮作(稻-麦、稻-油)而言,土地利用方式显著影响了土壤速效钾和缓效钾含量变化,稻-蔬轮作提高了表层土壤速效钾和缓效钾含量,园林用地则加剧了土壤速效钾和缓效钾的消耗.对于较为稳定的土壤矿物钾和全钾而言,其含量在不同土地利用方式间均无显著差异.从深层土壤来看,稻-蔬轮作方式下速效钾含量随土层加深下降最为明显,传统轮作土壤速效钾含量显著高于园林用地,缓效钾变化趋势与速效钾相反.不同土地利用方式土壤矿物钾和全钾含量差异较小.在4种土地利用方式中,稻-蔬轮作方式下表层土壤速效钾和缓效钾占全钾比例相对其他3种土地利用方式较高,20～40 cm土层,不同土地利用方式下速效钾占全钾比例均显著下降,缓效钾随土层向下比例变化与速效钾变化趋势恰好相反.矿物钾占全钾比例在不同土地利用方式下无显著差异.可见,不同土地利用方式对成都平原土壤速效钾和缓效钾在剖面中的分布具有显著影响.

To explore the effects of land use change on the potassium in soil profile under the background of rapid urbanization,we collected data of 187 soil profiles from four typical land use patterns(rice-wheat,rice-vegetable,rice-oil and garden)in Chengdu Plain.The contents of available potassium(AP),slow-acting potassium(SP),mineral potassium(MP),and total potassium(TP)in soil profile under different land use patterns and their relationships were analyzed.Our results showed that compared with the traditional rotation(rice-wheat,rice-oil),soil AP and SP contents significantly varied among different land use patterns.Rice-vegetable rotation increased the contents of AP and SP in the surface soil,while garden land increased the consumption of AP and SP in the soil.For the more stable forms,soil MP and TP,there was no significant difference in their contents under different land use patterns.In the deep soil,the content of AP in the rice-vegetable rotation pattern was significantly decreased with deepening soil layer,and the AP in traditional rotation was significantly higher than that in garden land.The trend of SP was opposite to that of AP.The difference of MP and TP in different land use patterns was small.Among the four land use patterns,the ratio of AP to TP and SP to TP in the lower layer of rice-vegetable rotation was higher than that in other patterns,while the ratio of AP to TP decreased significantly under different land use patterns at 20-40 cm.The change of SP to TP with the downward ratio of soil layer was opposite to that of AP to TP.Additionally,the ratio of MP to TP was relatively stable under different land use patterns.Therefore,different land use patterns exerted significant effects on the distribution of AP and SP in the soil profile of Chengdu Plain.