【摘要】 【目的】阐明不同种植年限蔬菜大棚土壤pH值、电导率及养分含量的时空变化特征,为保护性耕作土壤的可持续利用提供科学依据。【方法】以西藏林芝地区不同种植年限(2,7和15年)蔬菜大棚及相邻农田土壤为研究对象,分析0～70 cm土层(每10 cm为一个土层)土壤pH值、电导率值及有机质、全氮、速效氮、速效磷、速效钾含量的变化。【结果】随着土层深度的增加,不同种植年限蔬菜大棚及农田土壤pH值均呈逐渐增加的趋势,与农田土壤相比,蔬菜大棚土壤酸化程度更严重;随着蔬菜大棚种植年限的延长,土壤pH值呈"V"型变化,在种植7年时,土壤pH值最小,为5.08±0.22。土壤电导率值随土层深度的增加呈降低的趋势,且表聚现象十分明显,蔬菜大棚土壤电导率值随土层深度增加的垂直空间变异性较农田明显;随蔬菜大棚种植年限的增加,土壤电导率值呈增加的趋势,在蔬菜大棚使用初期土壤电导率值增加幅度较小,但随着种植年限的延长,土壤电导率增加幅度加大。有机质、全氮及速效氮、速效磷、速效钾含量随土层深度的增加均呈降低的趋势,与农田相比,蔬菜大棚土壤上述养分含量的"表聚"现象明显;随蔬菜大棚种植年限的延长,土壤有机质、全氮及速效氮、速效磷、速效钾含量均呈增加的趋势,说明蔬菜大棚土壤养分累积现象十分明显。Pearson相关性分析结果表明,土壤各理化指标之间均表现出显著或极显著的相关性。【结论】在藏东南八一镇大棚生产过程中,土壤酸化现象严重,表层养分累积明显,存在环境风险,故在生产管理中宜适当控制化肥的施用量,提倡科学施肥,以保证设施大棚土壤的可持续利用及生态环境安全。更多还原

【Abstract】 【Objective】 This study elucidated the spatio-temporal characteristics of soil pH,conductivity and nutrient contents in greenhouse with different planting years to provide basis for sustainable use of conservation tillage soils.【Method】 The vegetable sheds(2 a,7 a and 15 a) and neighboring farmland soils at different planting ages in Nyingchi,Tibet were selected to measure soil pH,conductivity,and contents of organic matter,total nitrogen and available N,available P and available K at depths of 0-70 cm.【Result】 Soil pH in vegetable greenhouses at different planting years and farmland gradually increased with the increase of soil depth.Soil acidity in vegetable greenhouses was more severe compared with farmland.Soil pH showed a V-shaped with the extension of planting years,and the smallest value of 5.08±0.22 was found in 7 a greenhouse.Soil conductivity decreased with the increase of soil depth,and surface aggregation was very significant.The vertical spatial variability of soil conductivity in vegetable greenhouses was more significant than in farmland.With the increase of planting years,the soil conductivity showed an increasing trend.In the early stage of vegetable greenhouse,the soil conductivity increased slightly.With the further extension of planting years,the soil conductivity increased more significantly.Soil organic matter,total nitrogen,and available nitrogen,phosphorus,and potassium contents decreased with the increase of soil depth.the "surface aggregation" phenomenon in the vegetable greenhouse soil was more significant compared with the farmland. Soil organic matter,total nitrogen,and available N,P,and K contents increased with the increase of planting years,indicating significant accumulation of soil nutrients in vegetable greenhouses.Pearson correlation analysis showed that there was significant or extremely significant correlations between soil physical and chemical indicators.【Conclusion】 During the production process of greenhouses in Bayi Town,southeastern Tibet,soil acidification was severe and soil surface nutrient accumulation was significant,resulting in environmental risks.It is advisable to appropriately control the application amount of chemical fertilizers in production management and to promote scientific fertilization for sustainable use of soil and ecological and environmental safety of greenhouses.更多还原