[Effects of Plastic Film Mulching and Biochar Application on N₂O Emission from a Vegetable Field]

The aim of this research was to examine the effects of biochar addition (B0:0 t·hm^-2, B20:20 t·hm^-2, and B40:40 t·hm^-2) and mulching (FM:film and NM:no film) on vegetables. The impact of N₂O emissions in the field was based on the pepper-radish rotation vegetable field system on the farm of Southwest University, using static dark box/gas chromatography to conduct in-situ observations in the field for one year. In this experiment, a total of six treatments were set up, namely NMB0 (CK) and FMB0, NMB20 and FMB20, and NMB40 and FMB40. The results showed that FM significantly increased the content of ammonium and nitrate nitrogen in the pepper season soil (P<0.05) but had no significant effect on soil environmental factors in the radish season. Compared with that of NM, the pepper season FM increased the N₂O emissions of the B0, B20, and B40 treatments by 52.87%, 52.97%, and 52.49% (P<0.05), respectively, but the radish season FM had no significant effect on N₂O emissions. Biochar had no significant effect on soil environmental factors in the pepper and radish seasons. The addition of biochar in the radish season reduced N₂O emissions by 28.76%-67.88% (P<0.01), and the addition of biochar in the pepper season had no significant effect on N₂O emissions. Compared with that of NM, under different biochar levels, FM increased the yield of pepper by 15.85%-161.32% and increased the yield of radish by 43.97%-75.80%. Biochar significantly increased the yield of peppers and had no significant effect on the yield of radishes. Regardless of whether the film was covered or not, when the amount of biochar added was 20 t·hm^-2, the yields of pepper and radish were the highest. The analysis of N₂O emission intensity revealed that FM in the pepper season significantly reduced N₂O emission intensity, whereas in the radish season FM and biochar significantly reduced N₂O emission intensity, and both planting seasons reached the lowest N₂O emission intensity under the FMB20 treatment. Therefore, mulching and applying 20 t·hm^-2 biochar were the best farmland management measures for the pepper season and radish season, which could achieve high yields and the lowest N₂O emissions, accomplishing a win-win for economic and environmental benefits.