Abstract:
Objective Amino sugar nitrogen (ASN), a key component of microbial residues, is an important indicator of microbial involvement in soil nitrogen (N) cycling. This study aimed to clarify the accumulation patterns and compositional changes of ASN under different maize straw return rates, providing insights into the microbial role in soil N retention and turnover.
Method A 9-year long-term field experiment was conducted in Northeast China with three treatments: chemical fertilizer alone (T0), chemical fertilizer with 50% straw return (T1), and chemical fertilizer with 100% straw return (T2). Soil total N (TN) and the concentrations of three kings of ASN—glucosamine N (N-GluN), galactosamine N (N-GalN), and muramic acid N (N-MurN)-were measured to assess ASN accumulation and its composition over time.
Result Both T1 and T2 treatments significantly increased TN and total ASN contents, with the accumulation of ASN exceeding that of TN. By the 9th year, the total ASN content in T2 increased by 67.1% compared to the 1st year, accounting for 7.31% of TN. Straw return significantly enhanced the accumulation of fungal-derived N-GluN, particularly under the high straw input. In contrast, bacterial-derived N-MurN increased more under the lower straw input treatment. N-GalN content increased progressively with both straw return rate and duration.
Conclusion Long-term straw return promoted N assimilation and significantly enhanced soil N accumulation. High-rate straw return accelerated the accumulation of microbial residues, particularly fungal residues, thereby increasing the size and stability of the soil N pool. These findings provide scientific evidence for improving N use efficiency and guiding sustainable soil management in agroecosystems.
下载: