不同耕作措施下温度升高对旱作春小麦农田土壤N_(2)O排放的影响

Effects of temperature rise under different tillage measures on N_(2)O emission in dryland spring wheat farmland soil

为探究不同耕作措施下温度升高对旱作春小麦农田土壤N_(2)O排放的影响效应,基于APSIM模型,结合甘肃省定西旱作春小麦试验区定点连续监测的N_(2)O排放通量等数据,检验该模型模拟不同耕作措施下N_(2)O排放的适宜性,并对不同耕作措施下日最高、最低温在02℃范围内耦合变化时旱作春小麦农田土壤N_(2)O排放进行模拟。结果表明:APSIM模型对不同处理下N_(2)O排放的模拟结果与实测结果较为一致,归一化均方根差(NRMSE)最大值为0.17,决定系数(R^(2))最小值为0.80,相关性均达到显著水平(P<0.05),说明该模型可以用来模拟不同耕作措施下旱作麦田N_(2)O排放;在试验设计范围内,日最高温不变、日最低温升高会增加N_(2)O排放,增排效果表现为传统耕作(T)>免耕(NT)>传统耕作+秸秆覆盖(TS)>免耕+秸秆覆盖(NTS),日最低温每升高0.5℃,最大增排幅度为2.41%;日最低温不变、日最高温升高会减少N_(2)O排放,减排效果表现为T>TS>NT>NTS,日最高温每升高0.5℃,最大减排幅度为1.68%。日最低温升高带来的增排效应大于日最高温升高带来的减排效应。

To explore the effects of temperature increase on N_(2)O emissions in dryland spring wheat farmland soil under different tillage measures,the APSIM model,combining with datas from fixed-point and continuous monitoring of N_(2)O emission fluxes from the dryland spring wheat test area in Dingxi,Gansu Province was adopted in the study.The model was tested to simulate different farming practices.The suitability of N_(2)O emission under the measures,and the simulation of N_(2)O emission from dryland spring wheat farmland soil when the daily maximum and minimum temperature under different cultivation measures were coupled in the range of 02℃.The results showed that the APSIM model's simulation results of N_(2)O emissions under different treatments were more consistent with the measured results.The minimum determination coefficient R^(2) was 0.80,and the maximum normalized root mean square error(NRMSE)was 0.17,indicating that the model could be used to simulate different farming.Under the measures,N_(2)O emissions from dry farming wheat fields;within the scope of the experimental design,the daily maximum temperature remained unchanged,and the daily minimum temperature rises increased N_(2)O emissions.The effect of increased discharge is traditional tillage(T)>non-tillage(NT)>traditional tillage+straw mulch(TS)>non-tillage+straw mulch(NTS),and the maximum increase of discharge rate was 2.41%for every 0.5°C increase in the daily minimum temperature.The daily minimum temperature remained unchanged,and the daily maximum temperature rises reduced N_(2)O emissions.The emission reduction effect was as follows:T>TS>NT>NTS.For every 0.5°C increase in the daily maximum temperature,the maximum emission reduction rate was 1.68%.The increase in emissions caused by the increase in the daily minimum temperature was greater than the emission reduction effect caused by the increase in the daily maximum temperature.