Wu Si, Zhang Zhenhua, Sun Haijun, Hu Haibo
Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China.
Jiangsu Key Laboratory for Bioresource of Saline Soils, School of Wetlands, Yancheng Teachers University, Yancheng 224007, China.
Plants (Basel). 2023 Jun 25;12(13):2446. doi: 10.3390/plants12132446.
It is of agronomic importance to apply nitrogen (N), but it has high environmental risks in reclaimed saline soils. Therefore, we should apply N fertilizer at an appropriate rate to increase crop yield but decrease N losses. In this soil column experiment, rice yield, N uptake, and ammonia (NH) and nitrous oxide (NO) losses were measured in four treatments with no N application (control) and with N applications of 160, 200, and 240 kg/ha (N160, N200, and N240, respectively). The results show that grain yield, spike number, and thousand-kernel weight increased with increases in N application rate, but there was no significant difference in grain yield between N200 and N240. However, the kernels per spike increased first and then decreased with the increase in N application, of which N200 was recorded to have the highest kernels per spike value, which was 16.8 and 9.8% higher than those of N160 and N240, respectively. Total NH volatilization of the rice season increased with increasing N input, especially during the first and second supplementary fertilization stages. The NH-N concentration of overlying water was relatively lower under the N200 treatment in these two stages, and the yield-scaled NH volatilization and the emission factor were the lowest in N200, which were 26.2-27.8% and 4.0-21.0% lower than those of N160 and N240, respectively. Among the three N-applied treatments, NO losses and the emission factor as well as the yield-scaled NO emissions were the lowest under the N200 treatment, which had 34.7% and 78.9% lower NO emissions and 57.8% and 83.5% lower emission factors than those of the N160 and N240 treatments, respectively. Moreover, the gene copies of AOA and AOB , , and in cultivated layer soils all reached the minimum under the N200 treatment. According to the comprehensive effects of N fertilizer on rice grain yield and NH and NO losses, we recommend applying 200 kg/ha to reclaimed saline soil to ensure crop yield and reduce N losses.
施用氮肥具有重要的农艺意义，但在复垦盐碱地中存在较高的环境风险。因此，应合理施用氮肥以提高作物产量并减少氮素损失。在本土柱试验中，设置了不施氮（对照）以及施氮量分别为160、200和240 kg/公顷（分别为N160、N200和N240）的四个处理，测定了水稻产量、氮素吸收以及氨（NH）和氧化亚氮（NO）损失。结果表明，随着施氮量增加，稻谷产量、穗数和千粒重均增加，但N200和N240处理的稻谷产量无显著差异。然而，每穗粒数随施氮量增加先增加后减少，其中N200处理的每穗粒数最高，分别比N160和N240高16.8%和9.8%。水稻季总NH挥发量随氮投入增加而增加，尤其是在第一次和第二次追肥阶段。在这两个阶段，N200处理下覆水的NH-N浓度相对较低，且N200处理的产量尺度NH挥发量和排放因子最低，分别比N160和N240低26.2 - 27.8%和4.0 - 21.0%。在三个施氮处理中，N200处理下的NO损失、排放因子以及产量尺度NO排放量最低，其NO排放量分别比N160和N240处理低34.7%和78.9%，排放因子分别低57.8%和83.5%。此外，在N200处理下，耕层土壤中氨氧化古菌（AOA）和氨氧化细菌（AOB）的基因拷贝数均达到最低。根据氮肥对水稻籽粒产量以及NH和NO损失的综合影响，建议在复垦盐碱地中施用200 kg/公顷氮肥，以确保作物产量并减少氮素损失。
