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| Impacts of different forms of nitrogen on the decomposition of wheat straw by Aspergillus niger |
| Received:March 08, 2022 Revised:April 25, 2022 |
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| KeyWord:Aspergillus niger;nitrogen form;wheat straw decomposition;enzyme activity;structural equation modeling |
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| Abstract: |
| The effect of exogenous addition of different forms of nitrogen on the decomposition of wheat straw by Aspergillus niger was assessed. The effects of different forms of nitrogen on residue mass, microbial biomass, and extracellular enzyme activity during the decomposition of wheat straw were studied by an indoor shaking culture method. The five treatments conducted in the laboratory were as follows： wheat straw（W） , wheat straw + A. niger（WA） , wheat straw + A. niger + ammonium sulfate（WAA） , wheat straw + A. niger + urea （WAU） , and wheat straw+A. niger + potassium nitrate（WAP） . The treatment order of the decomposition rate of wheat straw was WAP （21.87%）>WAU（21.08%）>WAA（17.29%）>WA（14.23%）>W（7.86%） , and the order of the decomposition rate constant was KWAU （0.222） >KWAP（0.184） >KWAA（0.126） >KWA（0.072） >KW（0.059）after 30 days incubation. With the addition of different forms of nitrogen, the microbial biomass increased from 36.63% to 65.16%, β-glucosidase activity increased from 10.42% to 38.89%, acidic xylanase activity increased from 13.28% to 58.75%, manganese peroxidase activity increased from 2.80% to 26.60%, and laccase activity increased from 22.86% to 44.57%. Amide nitrogen and nitrate nitrogen produced the best results. A structural equation model also revealed that nitrogen addition increased the activity of straw-degrading enzymes by affecting the microbial biomass（SPC=0.45） , thereby promoting the decomposition of wheat straw. The findings indicate that A. niger can promote decomposition of wheat straw（P<0.05） . Exogenous addition of different forms of nitrogen, especially amide nitrogen and nitrate nitrogen, can significantly accelerate the decomposition of wheat straw by A. niger. Considering the input cost and practical application, urea is an ideal nitrogen source for promoting the decomposition of wheat straw by A. niger. |
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