李佳旺, 徐嘉, 于航, 罗慧, 沈菊培, 陈超, 白鑫, 岳中辉. 土壤脲酶酶促反应对3种有机氮肥施用的响应[J]. 中国生态农业学报 (中英文), 2024, 32(6): 1−10. DOI: 10.12357/cjea.20230602
引用本文: 李佳旺, 徐嘉, 于航, 罗慧, 沈菊培, 陈超, 白鑫, 岳中辉. 土壤脲酶酶促反应对3种有机氮肥施用的响应[J]. 中国生态农业学报 (中英文), 2024, 32(6): 1−10. DOI: 10.12357/cjea.20230602
LI J W, XU J, YU H, LUO H, SHEN J P, CHEN C, BAI X, YUE Z H. Response of the soil urease enzymatic reaction to the application of three organic nitrogen fertilizers[J]. Chinese Journal of Eco-Agriculture, 2024, 32(6): 1−10. DOI: 10.12357/cjea.20230602
Citation: LI J W, XU J, YU H, LUO H, SHEN J P, CHEN C, BAI X, YUE Z H. Response of the soil urease enzymatic reaction to the application of three organic nitrogen fertilizers[J]. Chinese Journal of Eco-Agriculture, 2024, 32(6): 1−10. DOI: 10.12357/cjea.20230602

土壤脲酶酶促反应对3种有机氮肥施用的响应

Response of the soil urease enzymatic reaction to the application of three organic nitrogen fertilizers

  • 摘要: 土壤脲酶(URE)是催化土壤氮素转化的重要酶类, 其酶促反应的动力学和热力学特性能够反映土壤氮素转化的方向和强度, 研究不同形式有机氮肥施用后的土壤脲酶酶促反应过程, 对于维持农田土壤氮素的供应有积极意义。通过为期60 d的小麦盆栽试验, 测定尿素(UR)、猪粪(PM)和白星花金龟子虫粪(BM)施用后土壤脲酶活性在不同温度和底物浓度下的变化, 运用公式计算酶动力学和热力学参数, 并分析其与土壤碳氮组分的关系。结果表明: 氮肥对土壤脲酶动力学和热力学参数均有显著影响(P<0.05); 而升温及其与氮肥的交互作用仅对土壤URE活性、土壤脲酶动力学参数和热力学参数ΔG有显著影响(P<0.05)。随温度升高, 3种氮肥处理土壤脲酶动力学和热力学参数都显著增加(P<0.05), 在35℃或45℃达到峰值。在各温度下, UR施用后土壤脲酶酶促米氏常数(Km)显著增加(P<0.05), BM施用后无显著变化, PM在不同温度下无规律性变化; 3种氮肥施用后土壤脲酶最大反应速率(Vmax)与米氏常数的比值(Vmax/Km)不变或显著降低(P<0.05); 除UR施用35℃、PM施用35℃和45℃以及BM施用5℃和45℃外, 土壤脲酶Vmax均显著升高(P<0.05)。UR和BM施用后酶促反应活化能(Ea)、热力学参数ΔH显著降低和ΔS显著增加(P<0.05), 而PM施用后无显著变化。统计分析结果表明, 氮肥施用后土壤URE活性及其动力学和热力学参数与土壤碳氮组分间存在一定的相关关系, 脲酶动力学和热力学参数是土壤氮素转化的主要因子。综上所述, 3种氮肥处理对土壤脲酶酶促反应的影响存在差异, 可以利用土壤脲酶酶促反应参数来指示氮肥施用后的土壤氮素变化; 与UR和PM相比, BM能够维持土壤脲酶与底物的结合能力, 降低反应所需的能量, 提高反应自发程度, 更有利于土壤氮素的转化。

     

    Abstract: Soil urease (URE) is an important enzyme that catalyzes the conversion of soil nitrogen, and the kinetic and thermodynamic properties of its enzymatic reaction respond to the direction and intensity of soil nitrogen conversion. The study of the enzymatic reaction process of soil urease after the application of different forms of organic nitrogen fertilizers has a positive significance for the maintenance of nitrogen supply in farmland soils. A 60-day wheat pot experiment was conducted to determine the changes in soil urease activity at different temperatures and substrate concentrations after the application of urea (UR), pig manure (PM), and Potosa brevitarsis manure (BM), to calculate enzyme kinetic and thermodynamic parameters using formulae, and to analyze their relationship with soil carbon and nitrogen fractions. The results showed that nitrogen fertilizers significantly affected both soil urease kinetic and thermodynamic parameters; whereas warming and its interaction with nitrogen fertilizers only significantly affected soil URE activity, soil urease kinetic parameters, and thermodynamic parameter ΔG. The kinetic and thermodynamic parameters of soil urease in the three nitrogen fertilizer treatments increased significantly with increasing temperature and peaked at 35℃ or 45℃. At each temperature, the Michaelis constant (Km) of soil urease increased significantly after UR application, no significant change was observed after BM application, and PM did not change regularly at different temperatures; the ratio of the maximum speed of urease reaction (Vmax) to Km (Vmax/Km ) of soil urease remained unchanged or decreased significantly after the three nitrogen fertilizers were applied; except for urea at 35℃, pig manure at 35℃ and 45℃, and P. brevitarsis manure at 5℃ and 45℃. Soil urease Vmax, activation energy of reaction (Ea) and thermodynamic parameter ΔH were significantly decreased and thermodynamic parameter ΔS was significantly increased by UR and BM, while no significant change was observed in PM. Statistical analysis showed a correlation between soil URE activity, its kinetic and thermodynamic parameters, and soil carbon and nitrogen fractions after nitrogen fertilizer application. The kinetic and thermodynamic parameters of urease were the main factors affecting soil nitrogen transformation. In summary, the effects of the three nitrogen fertilizer treatments on the enzymatic reaction of soil urease differed, and the parameters of the enzymatic reaction of soil urease could be used to indicate the changes in soil nitrogen after nitrogen fertilizer application. Compared with UR and PM, BM was able to maintain the binding capacity of soil urease and substrate, reduce the energy required for the reaction, and improve the spontaneity of the reaction, which is more conducive to the conversion of soil nitrogen.

     

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