氮肥用量与运筹对水稻氮素吸收转运及产量的影响

应用15N示踪技术研究了大田条件下氮肥用量与运筹对水稻氮素吸收、转运及籽粒产量的影响。试验分别设置3个氮肥水平(0、150和240 kg/hm2N)和两种基追比例(即基肥:蘖肥穗粒肥分别为40%︰30%︰30%(A)和30%︰20%︰50%(B)),共5个处理,依次记作N0、N150A、N150B、N240A、N240B。结果表明,在0~240 kg/hm2范围内,提高氮肥水平,显著增加水稻吸收的肥料氮素、土壤氮素数量以及肥料氮在土壤中的残留量。成熟期高氮处理(240 kg/hm2)水稻吸收的肥料氮素、土壤氮素及肥料氮在土壤中的残留量较多,分别为110.25、65.91、32.69 kg/hm2,而氮素的吸收利用率和土壤残留率下降,氮素损失率增加。在相同的氮肥水平下,采用基肥蘖肥穗粒肥比例为30%︰20%︰50%时,水稻吸收的肥料氮数量显著增加,氮素吸收利用率和土壤残留率提高,氮素损失率降低。适量施氮并增加穗粒肥的施氮比例,可以显著增加水稻产量。在本实验条件下,施氮量为240 kg/hm2及基肥蘖肥穗粒肥为30%︰20%︰50%的施氮处理是兼顾产量和环境的最佳氮肥运筹方式。

Effects of nitrogen rate and its basal to dressing ratio on uptake, translocation of nitrogen and yield in rice

The effects of nitrogen rate and its basal to dressing ratio on the uptake, translocation of nitrogen and yield in rice were studied by using 15N isotope tracing in the micro-plot experiment. There were three N rates (0, 150, 240 kg/hm2 N, respectively) and two different fractions being applied, viz, A (40% at basal, 30% at 10 days after transplanting (DAT), 30% at 36 DAT) and B (30% at basal, 20% at 10 DAT, 50% at 36 DAT) for each N rate, which were expressed as N0, N150A, N150B, N240A and N240B, respectively. At the same time, the field experiment was conducted in the same field, and experimental design was same as that of the 15N isotope tracing experiment with three repetitions. 15N isotope tracing experiment showed that the amounts of nitrogen derived from fertilizer(Ndff) and soil(Ndfs) absorbed by rice and residual amount in the soil were significantly increased as the increase of nitrogen rate from 0 to 240 kg/hm2 N. Compared to other nitrogen rate treatment, more Ndff and Ndfs absorbed by rice and residual amount in the soil of 240 kg/hm2 N treatment at the maturity stage were found, which was 110.25, 65.91 and 32.69 kg/hm2 respectively. However, nitrogen recovery efficiency and residual amount in the soil was decreased, increasing in the unaccounted nitrogen rate. When nitrogen was applied at the same nitrogen rate in three splits as 30% basal, 20% 10 DAT, 50% 36 DAT, compared with the N splits as 40% basal, 30% 10 DAT, 30% 36 DAT, the amount of Ndff absorbed by rice was markedly increased, nitrogen recovery efficiency improved, the unaccounted nitrogen rate decreased at maturity stage. Appropriate nitrogen fertilizer rate with increasing topdressing nitrogen amount such as N240B treatment increased grain yield. In conclusion, under the condition of this experiment, as far as grain yield and environmental benefits are concerned, the most appropriate nitrogen fertilizer applying regime recommended is N240B treatment, its nitrogen fertilizer rate is 240 kg/hm2 N and 30% for basal, 20% for 10 DAT and 50% for 36 DAT.