强酸性茶园土壤中添加不同肥料氮后N2O释放量变化

摘要

In recent years the long-term application of large amount of nitrogen fertilizers has led to the serious acidification of tea orchard soils with high N2O emission .In this study , different N fertilizers were applied to a highly acid tea orchard soil to evaluate the effects of N fertilizers on N2O emission.The results suggest that all the treatments increase N2O production significantly by the 31 days ’ aerobic incubation .The average N2O emission from the KNO3 treatment is the highest and total emission is 17 times higher than that of the control .The N2O emission of the NH 4 NO3 treatment is the next .The total N2O productions from the urea [ CO(NH2)2] and ( NH4 ) 2 SO4 treatments are stimulated but the N2O emissions are significantly lower than that of the KNO3 treatment.The Urea, (NH4)2SO4 and NH4NO3 treatments significantly stimulate soil nitrification activity, while the KNO3 treatment decreases nitrification potential .The results that denitrification is the dominant source of N2O emission in the highly acid tea orchard soil .To find out the microbial mechanism , quantitative PCR of the functional gene of nitrous oxide reductase ( nosZ) was determined.The results suggest that nosZ gene copies from the KNO3 treatment are significantly(P<0.05) lower than those of the control.Therefore, the inhibition of N2O reductase is one of the important factors to induce the high N2O emission in the highly acid soil .%茶园由于长期偏施氮肥，造成土壤酸化现象严重和N2 O大量排放。本文对强酸性茶园土壤进行不同氮肥处理试验，结果表明，通过31 d的好气培养，各施肥处理均显著提高N2 O排放，其中施硝酸钾（ KNO3）处理平均每天排放的N2O最高，总排放量为对照（CK）的17倍，其次是硝酸铵（NH4NO3）处理，尿素[CO（NH2）2]和硫酸铵[（NH4）2SO4]处理虽然能增加N2O排放，但远远小于硝酸钾处理。对各氮肥处理硝化势的测定表明，尿素、硫酸铵和硝酸铵处理均明显增加土壤硝化活性，而硝酸钾处理硝化势与对照相比显著降低。强酸性茶园土壤中N2 O排放的主要来源是反硝化作用。氧化亚氮还原酶（ nosZ）的定量PCR分析表明，硝酸钾处理的nosZ基因拷贝数与对照相比显著降低（ P＜0.05）。因此，强酸性土壤中N2 O还原酶活性被NO3-抑制是导致高N2 O排放的重要原因之一。