不同施氮水平对菜地土壤N_2O排放的影响

通过大田试验研究了不同施氮水平对蔬菜地土壤N2O排放的影响。试验设置5个氮水平0（N0）、430（N1）、860（N2）、1290（N3）、1640（N4）kgN.hm-2],2a试验期间种植的蔬菜有辣椒、萝卜、菠菜和小白菜。结果表明,施氮显著影响N2O排放通量,各施氮水平土壤N2O排放通量范围分别为-8~39、0.4~157、12~626、8.5~982、16~1342μg.m-.2h-1;同时,氮肥施用显著提高了N2O排放总量,各施氮处理（N0、N1、N2、N3和N4）试验期间土壤N2O平均排放总量分别为0.48、1.35、4.49、7.83、10.57kgN.hm-2,土壤N2O排放系数范围是0.33%~1.13%,且施氮水平与土壤N2O排放总量间呈显著的指数函数关系;不同季节蔬菜地土壤N2O排放总量差异很大,其中最大的是辣椒,最小的是菠菜;此外,土壤N2O排放通量季节变化除受施氮水平影响外,还受土壤温度的影响,排放高峰出现在高温的夏季。

Effects of Nitrogen Application Rates on Nitrous Oxide Emission from a Typical Intensive Vegetable Cropping System

Field experiment was conducted to study nitrous oxide（N2O）emission and its relationship with different nitrogen application rates in a continuous vegetable cropping system in Wuhan.Nitrogen was applied at 0（N0）,430（N1）,860（N2）,1 290（N3）and 1 640（N4）kgN.hm-2 to the plots during two experimental years.N2O emissions were measured for six rotational vegetables pepper（Capsicum annuum L.）,radish（Raphanus sativus L.）,Spinach（Spinacia oleracea L.）,pepper（Capsicum annuum L.）,Chinese cabbage（1）（Brassica Chinensis L.） and Chinese cabbage（2）].The results showed that nitrogen application significantly affected the N2O emission from this vegetable system,N2O emissions ranged from-8 to 39 μgN.m-.2h-1 for N0,from 0.4 to 157 μgN.m-2.h-1 for N1,from 12 to 626 μgN.m-2.h-1 for N2,from 8.5 to 982 μgN.m-2.h-1 for N3,and from 16 to 1 342 μgN.m-2.h-1 for N4.Application of nitrogen also significantly increased the total N2O emission,the average total N2O emission from five treatments（N0,N1,N2,N3 and N4）was 0.48,1.35,4.49,7.83 and 10.57 kgN.hm-2,respectively,the emission factor varied from 0.33% to 1.13%.There was an exponential relationship between nitrogen application rates and total N2O emission.Different seasonal vegetable crops had different total N2O emission,the largest total N2O emission was pepper,the lowest was spinach.In addition,soil temperature affected the seasonal variation of N2O emission,the peak emission of N2O occurred at summer when soil temperature was high.