玉米生长中的土壤呼吸及其受氮肥施用的影响

SOIL RESPIRATION DURING MAIZE GROWTH PERIOD AFFECTED BY N APPLICATION RATES

运用盆栽试验研究了玉米生长和施氮水平(N 150 mg kg-1和300 mg kg-1)对土壤呼吸的影响。结果表明种植玉米的土壤呼吸速率(C)的变化范围为19. 6 ~ 762. 1 mg m-2h-1,而裸土为4. 3 ~ 36mg m-2h-1。在玉米生长的条件下,苗期土壤呼吸最低,73%的土壤呼吸分配在拔节孕穗期和成熟期。玉米生长中各阶段根际呼吸对土壤呼吸的贡献在58%~98%,苗期最小。施氮对裸土呼吸速率无显著影响;在玉米生长的条件下,施用高氮的土壤呼吸比施用低氮高28%,且两种施氮水平下土壤呼吸的差异主要发生在生长中后期。玉米生长的条件下土壤呼吸与温度的相关性不显著,而裸土下土壤呼吸速率与气温、表土温度、5 cm土壤温度均呈极显著的相关性;裸土施用高氮下的土壤呼吸与温度的相关性大于低氮。总之,玉米生长和土壤施氮不仅影响土壤呼吸速率和呼吸量,也影响土壤呼吸在各生长阶段的分配,还影响到土壤呼吸与温度的关系。

The effects of maize growth and N-application (N 150 mg kg^(-1) and 300 mg kg^(-1)) on soil respiration were investigated in pot experiment. The results showed that in the maize-planted soil, the soil respiration rate ranged from C 19.6 to 762.1 mg m^(-2)h^(-1), but in the bare soil, it was in the range from C 4.3 to 36 mg m^(-2)h^(-1). Soil respiration rate was the lowest at the seedling stage and 73% of the soil respiration occurred at the elongating-booting stage and ripening stage. The contribution of maize rhizosphere respiration to soil respiration in each stage varied from 58% to 98% and was the lowest at the seedling stage. In the bare soil, N-application had no significant effect on soil respiration, whereas in the maize-planted soil, the soil respiration was 28% higher in the treatment of high N-application rate than in the treatment of low N-application rate during the whole maize-growing period. The significant difference between the two treatments only occurred in the metaphase and anaphase of maize growth. There was no significant correlation between soil respiration rate and temperature in the maize-planted soil, but in the bare soil, soil respiration rate was correlated exponentially to the temperature of the air, soil surface and at 5 cm depth significantly, and its correlativity was higher in the treatment of high N-application rate than in the treatment of low N-application rate. In conclusion, maize growth and soil N-application rate influenced not only the rate and intensity of soil respiration, but also the distribution of soil respiration in each developing stage of maize and the relationship between soil respiration rate and temperature.