Effects And Economic Benefits Analysis Of Different Fertilizer Treatments On N₂O Emissions From Spring Corn Field

Excessive fertilization is considered as a common problem in agricultural production activities ofChina, the application of chemical fertilizer becomes an important source of N₂O emissions. In order toincrease the nitrogen fertilizer use efficiency and reduce N₂O emissions, a field experiment wasundertaken during spring corn growing season in Shanxi Province to investigate the effect of sevenfertilizer treatments on N₂O emissions, in addition to corn yield, the economic benefits of differenttreatments were analyzed. Fertilizer treatments included urea （U）, urea mixed with10%and5%byN-weight of dicyandiamide （DCD1, DCD2）, sulfur coated urea （SCU）, urea mixed with10t·ha^-1and20t·ha^-1biochar （BC1, BC2） and non-fertilizer （CK）. This study provided scientific theoretical basis forslowing down global warming and popularizing new type of fertilizer. During this research an automaticsampling and analyzing system was taken for two consecutive years, based on the data of two yearsbefore observed by our group, a long-term dynamic analysis in the same field; comparison of the effectsof slow-release fertilizer and nitrification inhibitors on emission reduction; the effects of biochar onN₂O emissions and economic benefits of different treatments were studied. The main results are shownas follows:（1） The effects of environment factors on N₂O emissions.There was a pronounced variation of N₂O emissions from different fertilizer treatments during corngrowing season. The peak of N₂O emissions was influenced by precipitation and irrigation. N₂Oemissions increased with the increase of water-filled porsepace （WFPS）, when it ranged from60%to70%and76%to81%; the maximum of N₂O emissions was occurred while WFPS ranged from60%to70%; N₂O emissions was at low level when WFPS ranged from70%to76%or lower than60%. Theoptimum temperatures for N₂O emissions were between18℃and26℃.（2） The effects of different fertilizer treatments on N₂O emissions and corn yield.①Compared with U treatment, urea mixed with10t·ha^-1and20t·ha^-1biochar could reduce N₂Oemissions by15.3%and28.9%, respectively. There was no difference among the three treatments. Theapplication of20t·ha^-1biochar could increase the yield of spring corn （P＜0.05）, there was nosignificant difference between10t·ha^-1biochar and urea in yield.②Dicyandiamide could reduce N₂O emissions, emission reduction ranged from31.6%to59.5%. Theemission reduction of urea mixed with10%by N-weight of dicyandiamide （DCD1） was better than ureamixed with5%by N-weight of dicyandiamide （DCD2）, there was no significant difference between thetwo treatments. There was no difference on corn yield between dicyandiamide treatments and ureatreatment.③Based on the data from2009to2012, sulfur coated urea （SCU） had a significant role in N₂Oemission reduction that ranged from42.1%to59.7%. SCU had a role in increasing the yield of springcorn, but this effect on yield is gradually decreased with the long-term single application of SCU.④Compared with urea treatment, the emission reduction of SCU and DCD1were better than other treatments. Emission reduction of different treatments was SCU（2009）＞DCD1（2011）＞SCU（2010）＞DCD2（2011）＞SCU（2012）＞DCD1（2012）＞DCD2（2012）＞BC2（2012）＞BC1（2012）＞SCU（2011）.（3） The emission intensity and economic benefits of different treatments.The emission intensity of different treatments was SCU（2009）＜SCU（2010）＜DCD1（2011）＜SCU（2012）＜DCD1（2012）＜DCD2（2011）＜DCD2（2012）＜SCU（2011）. The net incomeof different treatments was SCU（2009）＞SCU（2010）＞SCU（2011）＞DCD1（2011）＞DCD1（2012）＞DCD2（2012）＞SCU（2012）＞DCD2（2011）. SCU and DCD1fertilization had the highereconomic benefits while reducing N₂O emissions, this fertilizing scheme can be extended in the NorthChina spring corn zone.