秸秆还田配施生物炭对关中平原夏玉米产量和土壤N2O排放的影响

为探明秸秆还田配施生物炭对夏玉米产量和土壤氧化亚氮（N₂O）排放的影响，基于2019~2020年关中平原田间定位试验，利用静态暗箱-气相色谱法监测了土壤N₂O排放通量，综合分析夏玉米产量、土壤N₂O排放和土壤活性氮组分，明确了秸秆还田配施生物炭在培肥土壤、增产减排方面的效应.以秸秆不还田（S₀）为对照，设置秸秆还田（S）和秸秆还田配施生物炭（SB）共3个处理.结果表明，各处理N₂O排放峰值出现在秸秆还田后10 d，秸秆还田30 d后土壤N₂O排放通量处于较低水平，土壤N₂O排放通量与铵态氮（NH₄⁺-N）、无机氮、微生物量氮（MBN）和可溶性有机氮（DON）含量呈显著的正相关关系（P<0.05）.S较S₀显著增加夏玉米产量、N₂O累积排放量、单位产量N₂O累积排放量和土壤总氮（TN）含量，分别为7.4%~13%、65.8%~132.2%、54.6%~103%和27.8%~33%.虽然SB较S提高夏玉米产量（2.5%~3.3%）的趋势不显著（P>0.05），但是SB较S显著降低N₂O累积排放量和单位产量N₂O累积排放量，分别为24.0%~27.3%和26.4%~29.2%.在土壤N₂O排放通量达到峰值时，SB较S显著降低土壤N₂O排放通量45.1%~69.6%，生物炭能够缓解秸秆还田所诱发的土壤N₂O排放，具有削峰的作用.SB较S显著增加土壤总氮9.1%~12.2%.综合作物产量、N₂O排放和土壤总氮，对夏玉米生产而言，秸秆还田配施生物炭不仅培肥地力，提高夏玉米产量，而且减少单位产量N₂O累积排放量，是可供推广的兼顾作物产量和环境友好的适宜管理措施.

Effects of Straw Returning and Biochar Application on Summer Maize Yield and Soil N2O Emission in Guanzhong Plain

Here, we investigated the effects of straw returning combined with biochar application on summer maize yield and soil nitrous oxide (N₂O) emissions, based on a field location trial in the Guanzhong Plain from 2019 to 2020. The soil N₂O emission rates were monitored using the static chamber-chromatography method. A comprehensive analysis of summer maize yields, soil N₂O emissions, and soil labile nitrogen components was conducted to clarify the effects of straw returning combined with biochar application on improving soil fertility, increasing summer maize yield, and reducing greenhouse gas emissions. The three treatments were no straw returning (S₀), straw returning (S), and straw returning combined with biochar application (SB). The results showed that the peak of N₂O emissions from each treatment occurred 10 d after the straw return, and the rate of soil N₂O emissions remained at a low level after 30 d of straw return. The rate of soil N₂O emissions showed highly significant positive correlations (P<0.05) with ammonium nitrogen (NH₄⁺-N), inorganic nitrogen (SIN), microbial nitrogen (MBN), and dissolved organic nitrogen (DON) contents. S significantly increased summer maize yield, cumulative N₂O emissions, yield-scaled N₂O intensity, and total nitrogen (TN) content by 7.4%-13%, 65.8%-132.2%, 54.6%-103%, and 27.8%-33%, respectively, compared to those in S₀. Although the trend for SB to increase summer maize yield (2.5%-3.3%) compared to that in S was not significant (P>0.05), SB significantly reduced cumulative N₂O emissions and yield-scaled N₂O intensity by 24.0%-27.3% and 26.4%-29.2%, respectively, compared to that in S. SB significantly reduced the rate of soil N₂O emissions by 45.1%-69.6% at the peak of N₂O emissions compared to that in S. Biochar application mitigated soil N₂O emissions induced by straw return and had a peak-shaving effect. SB significantly increased soil total N by 9.1%-12.2% compared to that in S. Combining summer maize yield, soil N₂O emissions, and TN content, SB not only improved soil fertility and summer maize yield but also reduced yield-scaled N₂O intensity, making it a suitable management practice that can be replicated to balance crop yield and environmental friendliness.