调整氮肥基追比减少稻田氮素损失和保证直播稻产量

水稻直播条件下,苗期防涝排水会增大稻田氮素流失风险,适当调整氮肥基施和追施的比例,可降低这种风险。在N、P₂O₅、K₂O用量分别为180、75、105 kg·hm^-2的条件下,以江汉平原稻田氮肥习惯施用比例(基肥、分蘖肥、穗肥比例为6∶4∶0)为对照(CK),另设7个氮肥基追比的处理(基肥、分蘖肥、穗肥的比例分别为:T1,4∶6∶0;T2,4∶4∶2;T3,4∶2∶4;T4,2∶6∶2;T5,2∶4∶4;T6,0∶8∶2;T7,0∶6∶4),开展田间试验,实测不同处理下氨挥发损失、氮径流损失和水稻成熟期的产量。结果表明:T7处理总氮径流流失最小(8.79 kg·hm^-2),T3处理的氨挥发损失最小(11.90 kg·hm^-2),T7处理总的氮素损失最小(22.89 kg·hm^-2),T4处理的产量最高(9 270.0 kg·hm^-2)、T5处理的产量次之(9 150.0 kg·hm^-2)。综合考虑氮素损失和水稻产量,推荐基肥、分蘖肥、穗肥中氮素的施用比例为2∶6∶2或2∶4∶4。

Reducing nitrogen loss from paddy filed and ensuring yield of direct seeding rice by adjusting nitrogen base-topdressing ratio

Field drainage for waterlogging prevention at seedling stage of direct seeding rice increases the risk of nitrogen loss from paddy field. Appropriate adjustment of nitrogen base-topdressing ratio can provide scientific basis for risk reduction during this process. In the present study, N, P₂O₅, and K₂O application amount were set as 180, 75 and 105 kg·hm^-2, respectively. A field experiment was conducted with different nitrogen base-topdressing ratios. The conventional fertilization method in Jianghan Plain (the proportion of N in basal fertilizer, tillering fertilizer and panicle fertilizer was 6∶4∶0 ) was taken as the control (CK), and treatments were set according to the proportion of N in basal fertilizer, tillering fertilizer and panicle fertilizer, specifically, 4∶6∶0 (T1), 4∶4∶2 (T2), 4∶2∶4 (T3), 2∶6∶2 (T4), 2∶4∶4 (T5), 0∶8∶2 (T6), 0∶6∶4 (T7). The ammonia volatilization loss and nitrogen runoff loss during rice growth and rice yield under different treatments were measured in the field. It was shown that the nitrogen runoff loss was the smallest under T7 treatment (8.79 kg·hm^-2). The ammonia volatilization loss was the smallest under T3 treatment (11.90 kg·hm^-2). The total nitrogen loss was the smallest under T7 treatment (22.89 kg·hm^-2). The highest yield was found under T4 treatment (9 270.0 kg·hm^-2), which was followed by T5 treatment (9 150.0 kg·hm^-2). Given the nitrogen loss and rice yield, the recommended proportions of N in basal fertilizer, tillering fertilizer and panicle fertilizer in the experimental conditions were 2∶6∶2 and 2∶4∶4.