施氮水平对两种水稻产量影响的动态模拟及施肥优化分析

借助水稻生长模型ORYZA-0和氮肥管理模块，通过田间和水槽的水稻氮肥试验，对水稻模型和N素动态模块进行了验证。结果表明，模型模拟的不同N素水平水稻生物量、产量同实际测定值明显呈正相关。其中，氮肥用量160kg·hm^-2为最佳经济施氮量,通过获得的水稻参数和氮肥应用曲线模拟的氮肥运筹结果表明：1)在低N(N<100kg·hm^-2)水平下，氮肥应在移栽后35d内全部施入；2)当施氮量为100～200kg·hm^-2时，N应在移栽后45d内全部施入；3)当施氮量N>200kg·hm^-2时，氮肥应在移栽后60d内全部施入；4)随着施氮量的增加，后期施肥比重可略为增加。总体来看，模型不仅能较准确地模拟水稻生长动态，而且可以模拟水稻N吸收和积累的行为动态，从大田晚稻的氮肥运筹模拟结果可看出，氮肥应用次数越多，越接近施氮应用积累曲线的连续施氮产量模拟值(6199kg·hm^-2)，但是在实际生产中这会增加农民的用工量和生产成本，难以让农民接受。因而在生产实际中既能让生产者接受，又不致较多地影响产量和收入，在160kg·hm^-2(纯N)施用量下的最佳施肥方案为N素化肥分4次按0．2：0．3：0．3：0．2的比例，分别于移栽后5、20、30和40d施入，可获得5916kg·hm^-2的产量。

Dynamic simulation of nitrogen application level effects on rice yield and optimization analysis of fertilizer supply in paddy field

Field and water tank plot experiments were conducted in Zhejiang Province in 1999 to determine the effects of nitrogen application amount and times on rice growth and yield, and rice growth simulation model ORYZA-0 and nitrogen management module were used to establish a modified nitrogen effect-rice growth model. The simulated results presented a higher positive relationship with the measured results. According to the simulated and measured results, 160 kg.hm-2 was the economic nitrogen application amount for two rice varieties production, and the nitrogen application strategies were: 1) < 100 kg.hm-2 nitrogen fertilizer should be applied within 35 days after transplanting; 2) when the nitrogen application level was between 100-200 kg.hm-2, it should be applied within 45 days after transplanting; 3) if the nitrogen application amount exceeded 200 kg.hm-2, it should be put into paddy field within 60 days after transplanting; 4) as the nitrogen application amount increased, the nitrogen supply at the later rice growth stage should be increased. As for the second cropping rice, the more times the nitrogen applied in the field, the more closeness the rice yield reached the APCUM curve(optimized nitrogen curve) suggested. But in real rice production, it is impossible for farmers to adopt more times of N applying, since labor and cost will increase. Based on the experimental parameters and real rice production situation, the reasonable nitrogen application under 160 kg.hm-2 levels for high yielding second cropping rice was split into 4 times with fraction 0.2:0.3:0.3:0.2 at 5, 20, 30, 40 days after transplanting. The rice yield could reach 5,916 kg.hm-2, resulted in a 3.12% increase as compared with the yield under actual fertilizer application amount and timing.