土壤水分和氮添加对3种质地紫色土氮矿化及土壤pH的影响  

Effects of Soil Moisture and Nitrogen Addition on Nitrogen Mineralization and Soil pH in Purple Soil of Three Different Textures

作　　者：田冬[1] 高明[1] 徐畅 

机构地区：[1]西南大学资源环境学院,重庆400715 [2]重庆市烟草专卖局(公司),重庆400023

出　　处：《水土保持学报》2016年第1期255-261,共7页Journal of Soil and Water Conservation

基　　金：国家"十二五"科技支撑计划项目(2012BAD14B18)

摘　　要：为正确认识土壤水分、质地和外源氮添加对紫色土氮矿化作用和土壤pH的影响,以西南地区典型的紫色土为研究对象,通过90d的室内恒温（25℃）好气培养,研究了3种质地（粘土、粉粘壤土和砂土）紫色土在不同含水量（55%,65%和75%田间持水量）和尿素氮添加水平（0mg/kg土和250mg/kg土.）条件下,土壤氮矿化作用和pH的变化。结果表明：前30d的累积矿化氮量可占培养期间（90d）的78.48%～91.55%,且各处理的土壤累积矿化氮量和净矿化速率均随着培养时间的延长而快速增加;第30～90d,土壤累积矿化氮量增长缓慢,净矿化速率迅速下降并趋于稳定。土壤累积矿化氮量和净矿化速率在各培养阶段均随土壤水分含量的增加而逐渐增大,其中75%WHC（75%田间持水量）和75%WHC＋U（75%田间持水量＋尿素）处理的矿化作用最强。土壤质地从一定程度上对土壤的矿化产生影响,但其影响并不显著。外源氮添加能促进土壤氮矿化,其净氮矿化量和净矿化速率在各培养阶段均极显著（p〈0.01）高于未加氮处理,分别为未施氮处理的1.68～4.56倍,0.60～6.47倍。外源氮添加使土壤pH显著下降,55%WHC＋U、65%WHC＋U和75%WHC＋U处理分别下降了0.57,0.66,0.72个pH单位,土壤有酸化趋势。土壤pH值与土壤氮素净矿化速率呈极显著线性相关,净矿化速率对pH变化贡献巨大。总之,土壤含水量增加和外源氮添加均促进了土壤氮矿化,增加了土壤矿质氮含量,同时外源氮添加也加速了土壤pH下降,土壤有酸化趋势。In order to better understand the effects of soi1 water content,soil texture,and external nitrogen addition on nitrogen mineralization and soil pH of purple soil,we collected soil samples in typical purple soil region in southwest China and incubated them at 25℃for 90 dto explore the characteristics of soil net mineralization and soil pH.3levels of soi1 water content（55%,65%and 75% of water ho1 ding capacity（WHC））and 2levels of urea nitrogen application amount（0mg/kg soil and 250mg/kg soil）were established,and 3soil textures（sandy,silty clay loam and clay purple soil）were selected.The results showed that,in the first 30 days of incubation,the mineral N accumulation accounted for 78.48%~91.55% of that in the whole cultivation period（90d）,and the mineral N accumulation and net N mineralization rate increased rapidly with the extension of the incubation time.During the 30~90days of incubation,the mineral N accumulation of soil increased slowly,while the net N mineralization rate decreased rapidly and tended to be stable.It was showed that the accumulation of mineral N and net mineralization rate increased gradually with the increase of soil moisture at various stages of incubation,and the mineralization was the most strongest in 75% WHC（75% of water ho1 ding capacity）and 75% WHC＋U（75% of water ho1 ding capacity＋urea）treatments.The soil texture had a certain effect on the mineralization of soil,but its effect was not significant.The external nitrogen addition could promote soil mineralization,leading to significant increases in the net N mineralization amount and net N mineralization rate in various incubation stages（p〈0.01）,which were respectively 1.68~4.56 times and 0.60~6.47 times higher intreatments with nitrogen addition than those in no nitrogen treatments.The addition of nitrogen significantly decreased the soil pH,and soil pH was decreased by 0.57 pH units,0.66 pH units and 0.72 pH units when the soil water content was 55%,65%and 75% WHC,respectively.Soil acidification

关 键 词：土壤水分 土壤质地 矿化作用 有机氮 土壤酸化 紫色土 

分 类 号：S158.5[农业科学—土壤学] S153.4[农业科学—农业基础科学]