Structural composition of immobilized fertilizer N associated with decomposed wheat straw residues using advanced nuclear magnetic resonance spectroscopy combined with 13C and 15N labeling
Structural composition of immobilized fertilizer N associated with decomposed wheat straw residues using advanced nuclear magnetic resonance spectroscopy combined with 13C and 15N labeling
复制标题
DOI：
10.1016/j.geoderma.2021.115110
复制
发表时间：
2021
期刊：
影响因子：
6.1
通讯作者：
Xi Chen;M. Jin;Pu Duan;Jennifer Mejia;W. Chu;X. Ye;Xiaoyan Cao;K. Schmidt-Rohr;M. L. Thompson;Hongjian Gao;J. Mao
中科院分区：
文献类型：
--
作者：
Xi Chen;M. Jin;Pu Duan;Jennifer Mejia;W. Chu;X. Ye;Xiaoyan Cao;K. Schmidt-Rohr;M. L. Thompson;Hongjian Gao;J. Mao
When crop residues are returned to soil, nitrogen (N) from applied chemical fertilizers can be immobilized by microbial growth and incorporated back into the residues themselves to form organic N compounds with poor bioavailability. However, the chemical composition of these compounds has remained poorly understood. Knowledge of the chemical composition of immobilized fertilizer N is crucial for understanding its fate in the field and its associated impacts on fertilizer applications and management. Here, we characterized immobilized fertilizer N by coupling isotopic labeling of wheat straw (13C) and fertilizer N (urea-15N) with two advanced nuclear magnetic resonance (NMR) techniques, (13C{15N} rotational-echo double resonance, REDOR) and two-dimensional (2D)15N−13C heteronuclear single quantum coherence (HSQC) spectroscopy. We found that the immobilization of N under aerobic conditions was greater than that under anaerobic conditions (52% of fertilizer15N vs 38% of fertilizer15N). Under anaerobic conditions, most of the immobilized fertilizer15N was in the form of protonated amide N. Compared to anaerobic conditions,15N spectra of aerobic samples showed more diversity amongst N containing functional groups, including peptide-amides (54%), methylated amides (22%), amines (7%), anilides (5%) and heterocyclics (3%). Additionally, from the perspective of its structural composition, 55-80% of the immobilized fertilizer15N was estimated to be a potentially labile N fraction. Collectively, these results indicate that the immobilization of fertiziler N during aerobic decomposition of straw residues produces organic N functional groups with a strong potential for remineralization available for use by crops when they are released into soil.
