摘要
为了分析灌溉施肥活动引起的包气带土壤pH值变异特征及其对地球化学条件的响应,通过历时3 a的野外原位灌溉施肥试验,应用不同季节灌前、灌后6 m土层中不同深度的测定资料,系统分析了土壤pH对灌溉、施肥的响应过程,结果表明:各深度pH值呈弱变异性(CV=1.01%～2.28%),与灌溉前相比,灌后土壤pH值的均值和变异系数均呈现明显的变化;灌前包气带各层pH具有强烈的空间自相关性,灌后受水分、基质等相互作用影响,pH的空间自相关性有所减弱,C_0/(C_0+C)和变程a分别由7.23 m和3.54 m(灌前0 d)减少到3.26 m和2.76 m(灌后第10天)。土壤基质是决定土壤酸碱性的主要因素,在灌溉施肥活动对pH的响应过程中,地球化学条件(土壤含水量、土壤温度、土壤有机质(SOM)、氧化还原电位(RP)等)、土壤基质组成和氮底物浓度(NH^+_4-N)等的交互作用影响pH的动态。土壤含水量和温度单独对pH影响不显著,两者交互作用对pH有显著影响。引起土壤pH变化的主要变异源为Cl^-、土壤有机质(SOM)、NO^-_3-N、NH^+_4-N等营养物质和不同空间深度土壤基质的差异,表明灌溉施肥改变了包气带pH地球化学动力场、营养物质和土壤基质的交互作用,引起各深度的生物地球化学反应,控制pH值的空间变异特性。当包气带介质土壤水分变化时,首先营养物氨态氮以分子态或水合态形式被介质吸附,H^+得到释放,使得灌后第4天pH值下降。随着氨氧化过程中H^+的释放,pH在灌前和灌后第10天和第30天有显著差异。氨的氧化引起硝酸盐含量不断增加,使得硝酸盐对pH值的影响在灌后不断增强,相关系数由0.24(0 d,P<0.05)增加到0.41(30 d,P<0.01),而氨态氮对pH值的影响逐步降低,相关系数由0.43(0 d,P<0.01)降低为0.19(30 d,P>0.05)。
To reveal the variation of soil pH resulted from irrigation and fertilization and the changes in geochemical conditions in vadose zone,we conducted a three-year of irrigation and fertilization field test.Using the monitoring data at different depths of 6 m soil profile before and after irrigation in different seasons,we systematically analyzed the responding process of the soil pH to irrigation and fertilization.The results showed that the pH had low variability in all tests(CV=1.01% ~2.28% ).Compared with that before irrigation,its mean value and coefficient of variation(CV)changed responsively after irrigation.Before irrigation,the pH of each measured layer had strong spatial correlation,after irrigation due to the impact of water,substrate,and their interaction,the spatial correlation was weakened.The C0/(C0+C)decreased from 7.23 m and 3.54 m(0 d before irrigation)to 3.26 m and 2.76 m(10 d after irrigation),respectively.The pH mainly depended on the soil matrix.With the responding of the soil pH to the irrigation and fertilization,the geochemical conditions(soil moisture content,soil temperature,soil organic matter,redox potertial(RP),etc.),soil matrix,nitrogen concentration(NH4^+-N)and their interaction affected the dynamic characteristics of pH.The moisture content or temperature did not have significant impact to pH,but their interaction did.The soil nutrients such as Cl-,soil organic matter(SOM),NO3^--N,NH4^+-N and space soil matrix at different depths were the main causes for pH variation.These indicated that irrigation and fertilization processes changed the geochemical dynamics,soil pH,the interaction of nutrients and soil matrix components leading to the biogeochemical reaction that controlled the characteristics of pH at each depth.With the change in soil moisture,NH4^+-N was adsorbed as molecule or hydrated formand H^+was released.This resulted in the decrease in soil pH on the 4th day after irrigation.With the release of H^+in the process of ammonia oxidation,the pH lowered significantly after the irrigation on the 10th day and 30th day of irrigation.Due to ammonia oxidation process,the soil nitrate content increased,and its impact on pH enhanced step-by-step after irrigation,the correlation coefficient increased from 0.24(0 d,P<0.05)to 0.41(30 d,P<0.01).While the influence of NH4^+-N on pH gradually reduced,the correlation coefficient decreased from 0.43(0 d,P<0.01)to 0.19(30 d,P>0.05).
作者
狄龙
刘秀花
胡安焱
谢兰宝
刘光辉
DI Long;LIU Xiu-hua;HU An-yan;XIE Lan-bao;LIU Guang-hui(Forestry Industry Development Office of Yulin,Yulin,Shannxi 71900,China;Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education Chang’an University,Xi’an,Shaanxi 710054,China;College of Environmental Science and Engineering,Chang’an University,Xi’an,Shaanxi 710054,China)
出处
《干旱地区农业研究》
CSCD
北大核心
2019年第2期72-80,共9页
Agricultural Research in the Arid Areas
基金
国家自然科学基金资助项目(41273104)
陕西省自然基金(2012K12-03-06)
中央高校基础研究项目(310829161005)
高等学校学科创新引智计划(111计划)资助项目(B08039)
关键词
包气带
土壤PH
灌溉施肥
变异特性
响应过程
vadose zone
soil pH
irrigation&fertilization
variation characteristics
response process
