不同灌溉方式对保护地土壤酸化特征的影响

摘要

自连续13a在同一地块以不同灌溉方式进行灌溉试验的保护地,分层采集沟灌、滴灌、渗灌3个处理0～60cm土层土壤样品,研究灌溉方式对土壤酸化特征的影响.结果表明,3种灌溉处理土壤活性酸度和交换性酸含量均随着土层加深而降低,各处理间土壤活性酸度在0～40cm土层差异明显,总体为沟灌＞渗灌＞滴灌；土壤交换性酸差异出现在0～30cm土层,为渗灌＞沟灌＞滴灌；土壤交换性Al3+随土层加深呈先增加后降低的变化趋势,且以滴灌含量最低.各处理土壤盐基饱和度(BS)随土层加深而增加,在0～30cm土层为滴灌＞渗灌＞沟灌.土壤pH与交换性酸、硝态氮含量呈极显著负相关,与盐基饱和度、特别是Ca2+饱和度呈极显著正相关；Al3+占交换性酸比例与有机质含量呈极显著负相关.总之,保护地土壤酸化与硝态氮含量、盐基饱和度、有机质含量关系密切；与沟灌和渗灌相比,滴灌更利于抑制土壤酸化.%Soil samples for analysis were collected at different depths within 0 ~ 60cm from three plots different in irrigation mode in the same protected field where an irrigation experiment had been going on for 13 years to explore the effect of irrigation mode on characteristics of soil acidification. Analysis of the samples show that the soil active acidity and the content of exchangeable acid decreased with soil depth in all the treatments. Soil active acidity in the 0 ~40 cm soil depth varied sharply between the treatments, displaying a general order of furrow irrigation > subsurface irrigation > drip irrigation , while the differences in content of exchangeable acid between the treatments were significant mainly at the depth of 0 ~30cm, showing an order of subsurface irrigation > furrow irrigation > drip irrigation. Content of exchangeable Al increased first and then decreased with increasing depth in all the three treatments, but the lowest in the treatment of drip irrigation. Soil BS increased with soil depth and showed an order of drip irrigation > subsurface irrigation > furrow irrigation in the 0 ~30cm soil depth. Soil pH was negatively related to exchangeable acid and nitrate nitrogen, but positively to base saturation, especially exchangeable Ca + saturation, both to an extremely significant extent. The proportion of Al 3+ against exchangeable acid was negatively related to organic matter content, also to an extremely significant extent. In conclusion, soil acidification in protected fields is closely related to content of nitrate nitrogen, base saturation and content of organic matter. Compared with furrow irrigation and subsurface irrigation, drip irrigation is conducive to inhibition of soil acidification.