摘要
微生物对铵态氮(NH4+)和硝态氮(NO3-)具有不同的生物偏好性,两者电荷恰好相反致使两类离子具有各异的生物化学特征,两者间丰度的比例变化势必会影响土壤腐殖化的方向。论文以添加玉米秸秆的白浆土作为供试对象,通过添加相同氮素数量、不同形态氮素配比(NH4+∶NO3-为4∶1、NH4+∶NO3-为1∶1和NH4+∶NO3-为1∶4),试图揭示其对腐殖质组成变化的差异影响,结果表明:(1)无论外源氮素以何种形态为主,秸秆-白浆土混料中的微生物活性均可获得提升,其对混料中较易利用的水溶性有机碳(CWSS)、可提取腐殖酸(CHE)及胡敏酸(CHA)等组分皆可产生矿化分解作用,相比之下,铵硝等比例供应对CWSS及惰性的胡敏素组分(CHu)均可产生较为强烈的分解转化,在其驱动下,微生物对混料CHA的降解程度最高,使之结构趋于简单的程度最大,但CHA组分在此过程有"再合成"的可能;(2)受到硝态氮占优的供氮影响下,微生物可消耗混料CHE并使之降解片段进入CHu组分,不利于腐殖质活性的增加;(3)微生物利用外源以铵态氮为主的氮素形态更有利于其对CHA中较为简单有机分子片段的降解并使之向富里酸(CFA)转化,有利于腐殖质活性提升。
Microorganisms have the distinct biological preferences for ammonium-N （NH4＋：N） and nitrate-N （NO3--N）. The opposite electric charges of two nitrogen （N） forms make them possess different biochemical characteristics. The change in the ratio of NH4＋-N to NO3--N is bound to affect the direction of soil humification. Albic soil was amended with corn straw and with the same amount of N. And the ratio of two N forms （NH4＋：NO3-） was 4：1, 1：1 and 1：4. The objective of this research was to reveal their effects on the chemical composition of humic substances. The results were as follows： （1） No matter what kinds of N forms being dominated, Albic soil added with corn straw enhanced the microbial activity. In this process, the microorganisms mineralized and decomposed the relatively available matter such as water soluble substance （Cwss）, humic-extracted acid （CHE） and humic acid （C~ , while the supply of equal proportion of NH4＋-N and NO3--N promoted stronger mineralization and decomposition of Cw^s and inert humin （Cry） in Albic soil added with corn straw. Under its influence, the degradation to the CnA extracted from the mixtures by microorganisms was the highest and the molecular structure tended to be simpler, however, the Cna might be re-synthesized during the process. （2） When the total N supply was mainly dominated by NO3--N, the microorganisms consumed the CHE of mixtures and transformed their molecular fragments into the CHu fraction, which was not good for the enhancement of the humus activity. （3） The microbial utilization to total N mainly in the form of NHn^-N was more beneficial to the degradation of simpler organic molecules of CnA and made them transform to the fulvic acid （CrA）, which was of great benefit to increase the activity of humus. Key words： Nitrogen form; Albic soil; Corn straw; Humic composition
出处
《土壤通报》
CAS
CSCD
北大核心
2016年第4期944-948,共5页
Chinese Journal of Soil Science
基金
吉林省教育厅"十二五"科学技术研究项目(吉教科合字[2015]第375号)
吉林农业科技学院重点学科培育项目(吉农院合字[2015]第X004号)
国家自然科学基金项目(41401251)
吉林市科技计划项目(201464039)资助
