基于DNDC模型的红壤旱坡花生地N_(2)O排放模拟研究

Simulation of N_(2)O Emission from Sloped Peanut Field on Red Soil Based on DNDC Model

为探究DNDC模型在红壤旱坡地N_(2)O排放模拟的适用性,以赣北红壤旱坡花生地为研究对象,设置常规耕作和轻简化免耕2种处理,连续3年(2019—2021年)采用静态箱-气相色谱法开展N_(2)O排放的田间原位观测试验,研究不同耕作处理下N_(2)O排放特征及DNDC模型模拟效果。结果表明:DNDC模型对不同耕作处理下0~10 cm土壤温度(相关系数r为0.86~0.87)和作物产量(r为0.90)的模拟效果较好。该模型能较好地模拟花生季因施肥和降雨引起的N_(2)O排放波动变化,也能较好地模拟常规耕作下土壤N_(2)O排放峰,但会在一定程度上低估轻简化免耕的N_(2)O排放峰和排放总量,且模型对16 mm以下的降雨响应较小。土壤pH值、施肥量对红壤旱坡花生地N_(2)O排放的影响最大,降雨量、土壤有机碳含量和粘粒含量也是影响N_(2)O排放的重要因子。模型模拟2019年不同施肥量下N_(2)O排放总量与花生产量发现,氮肥施用量不能低于76.54 kg/hm^(2),也不宜超过106.78 kg/hm^(2)。研究结果可为红壤坡耕地作物种植优化、农业温室气体减排等提供理论依据。

To explore the applicability of the DNDC model in simulating N_(2)O emission from red soil slope farmland,two tillage treatments(conventional tillage and no-tillage) were set up for peanut field in northern Jiangxi Province.Field in-situ observation experiments of N_(2)O emission were carried out for three consecutive years(2019—2021) by static box-gas chromatography to study the characteristics of N_(2)O emission and the simulation effect of DNDC model under different tillage treatments.The results showed that the DNDC model had a good simulation effect on soil temperature in 0~10 cm(the correlation coefficient r was 0.86~0.87) and crop yield(r was 0.90) under different tillage treatments.The model could effectively simulate the fluctuation of N_(2)O emission which caused by fertilization and rainfall during peanut season,as well as the peak of N_(2)O emission under conventional tillage.However,this model would underestimate the N_(2)O emission peak and its total amount to some extent under no-tillage,and had a smaller response to rainfall which was below 16 mm.Soil pH value and fertilization amount had the greatest impact on N_(2)O emissions from sloped peanut field on red soil.Rainfall,soil organic carbon and clay content were also important factors affecting N_(2)O emissions.According to simulate N_(2)O emission and peanut yield under different amount of fertilizer application in 2019,it was found that the application amount of nitrogen fertilizer should not be less than 76.54 kg/hm^(2),and should not exceed 106.78 kg/hm^(2).The research results can provide theoretical basis for optimizing crop planting and reducing agricultural greenhouse gas emission in red soil slope farmland.