黄腐酸钾对植烟土壤氮素转化及N2O排放的影响

为了探究黄腐酸钾对植烟土壤氮素转化以及N2O排放的影响,采用实验室静态培养的方法,通过氮肥配施不同量黄腐酸钾来探究黄腐酸钾对植烟土壤氮转化以及N2O排放的影响。试验设置5个处理:CK,硝酸铵(200 mg N·kg^-1,下同);T1,硝酸铵+2.5 g·kg^-1黄腐酸钾;T2,硝酸铵+5 g·kg^-1黄腐酸钾;T3,硝酸铵+10 g·kg^-1黄腐酸钾;T4,硝酸铵+15 g·kg^-1黄腐酸钾。结果表明:与CK处理相比,添加黄腐酸钾显著降低了土壤中的无机氮含量;当黄腐酸钾添加量≥10 g·kg^-1时,土壤中可溶性有机氮含量显著增加;T1、T2、T3、T4处理的净矿化和硝化速率随黄腐酸钾添加量的增加而减小,且均显著小于CK处理(P<0.05);添加黄腐酸钾显著提高了N2O和CO2的排放速率和累积排放量(P<0.05),N2O和CO2累积排放量随黄腐酸钾添加量的增大而增大。另外,N2O累积排放量与CO2累积排放量之间存在显著的正相关关系(R2=0.97,P<0.001)。分析表明,添加黄腐酸钾促进了微生物对氮素的净同化作用,能够显著降低土壤中的无机氮含量。另外,添加黄腐酸钾也刺激了反硝化作用,提高了N2O累积排放量。CO2累积排放量可作为量化N2O累积排放量的辅助指标。

Effects of fulvic acid potassium on N transformation in and N2O emission from tobacco plantation soil

Here, we evaluated the effects of fulvic acid potassium on N transformation in and N₂O emission from tobacco soil using a laboratory static-culture method. The experiment included five treatments with an equivalent N basis:CK, ammonium nitrate (200 mg N·kg^-1); T1, ammonium nitrate + fulvic acid potassium (2.5 g·kg^-1); T2, ammonium nitrate + fulvic acid potassium (5 g·kg^-1); T3, ammonium nitrate + fulvic acid potassium (10 g·kg^-1); and T4, ammonium nitrate + fulvic acid potassium (15 g·kg^-1). When compared with the CK treatment, the fulvic acid potassium treatments significantly decreased the soil concentration of inorganic N, but the T3 and T4 treatments significantly increased the soil concentration of soluble organic N. Furthermore, the net mineralization and nitrification rates decreased with an increase in the addition rate of fulvic acid potassium, but they were significantly less than those of the CK treatment (P<0.05). The fulvic acid potassium treatment significantly increased the N₂O and CO₂ emission rates and cumulative emission compared with those of the CK treatment, and its effect significantly increased with an increase in the addition rate of fulvic acid potassium (P<0.05). In addition, there was a significant positive correlation between cumulative N₂O emission and CO₂ emission (R²=0.97, P<0.001). In summary, the addition of fulvic acid potassium promoted the net microbial immobilization of inorganic N, which could significantly decrease the soil concentration of inorganic N. Moreover, the addition of fulvic acid potassium stimulated denitrification, causing a significant increase in cumulative N 2O emission. Furthermore, a significant positive correlation between cumulative N₂O emission and cumulative CO₂ emission was observed, implying that cumulative CO₂ emission can be used as a potential indicator to quantify cumulative N₂O emission.