Effects of biochar combined with silicate fertilization on carbon emission intensity in a rice field under nighttime warming
In order to better understand the effects of biochar combined with silicate fertilizer on rice yield and greenhouse gas emissions(CH4 and N2O)in paddy fields under nighttime warming,field simulation experiments were conducted in two consecutive years(2019 to 2020)at the Agrometeorological Station,Nanjing,China.An orthogonal experimental design with three factors and three levels was adopted in this study.The three factors were nighttime warming,biochar application,and silicate application.The rice canopy was covered with aluminum foil reflective film at night(19:00-6:00)to simulate nighttime warming.The nighttime warming was set at three levels:control,ambient temperature,no film covering(W0),covering with 5 mm film(W1),and covering with 11 mm film(W2).The biochar application was set at three levels:control(B0),7.5 t·hm-2(B1),and 17.5 t·hm-2(B2).The silicate application was of three types:no silicate application(control,Si0)and steel slag(Si1)or ore powder(Si2),at an application rate of 200 kg·hm-2(calculated by SiO2).In 2019,the results showed that the average nighttime temperature of the 5-and 10-cm soil layer increased by 0.3-1.0℃and 0.2-0.7℃,respectively.In 2020,the average nighttime temperature of the canopy and middle parts of the rice plants increased by 0.1-0.2℃and 0.2-0.3℃,respectively.The CH4 emission flux from the rice field changed with single peak trend,with the peak and the highest cumulative emission occurring during the tillering-jointing period.The N2O emission flux from the rice field varied,showing a multi-peak trend.The cumulative emissions of CH4 and N2O under nighttime warming were lower than the corresponding values under ambient temperature(control).Biochar application combined with silicate fertilizer inhibited CH4 emission but promoted N2O emission in the paddy field.CH4 emission played a dominant role in contributing to the total sustained-flux global warming potential(SGWP),accounting for more than 84% of SGWP in the paddy field.Nighttime warming significantly reduced both rice yield and cumulative greenhouse gas emissions.Biochar application effectively alleviated the adverse effects of nighttime warming on the yield.The application of steel slag reduced the total SGWP and greenhouse gas emission intensity.In terms of rice yield and carbon emission reduction,the results of this study suggest that,in order to maintain rice production with low carbon emissions,application of biochar of 17.5 t·hm-2 and steel slag of 200 kg·hm-2(calculated by SiO2)is recommended in the southern region of Jiangsu,China.
国家科技期刊平台
