太湖地区定位施氮与耗竭后施氮对水稻产量及氮肥利用率的影响

Effects of Located Nitrogen Application and Nitrogen Application After Exhaustion on Rice Yield and Nitrogen Use Efficiency in the Taihu Lake Region,China

通过在太湖地区持续施氮和土壤氮耗竭1年后再施氮的对比试验,研究了施氮量对水稻产量、干物质积累、植株吸氮量、氮肥利用效率和土壤氮素的影响。经过3季(稻-麦-稻)不施氮处理,第3季作物水稻的产量显著下降,仅6673.42kg/hm2;持续施氮和氮耗竭1年后施氮处理的产量均随着施氮量的增加而提高,但增产幅度逐渐减小,当施氮量为300kg/hm2时,水稻产量最高,分别为10514.95kg/hm2和10472.36kg/hm2,施氮量继续增加时水稻都出现倒伏而减产;各施氮处理植株的干物质积累、总吸氮量和土壤全氮含量都随施氮量的增加而提高,而氮肥利用效率都随施氮量的增加而降低;氮耗竭1年后施氮处理与持续施氮处理之间的各项指标变化不明显,说明这些指标与氮耗竭1年后的土壤背景氮关系不密切,而与当季施氮量有关。

The results of located consecutive nitrogen application and nitrogen application at one year after soil nitrogen exhaustion were compared in the Taihu Lake Region, China where nitrogen fertilizer was excessly applied in rice-wheat cropping system. The effects of different nitrogen application rates on rice yield, dry matter accumulation, nitrogen uptake, nitrogen use efficiency and soil nitrogen content were studied. The rice yield decreased significantly after three cropping seasons without nitrogen application, with the rice yield of the third season being only 6673.42 kg/hm^2. When nitrogen application rate rose, the rice yield increased significantly both in the treatments of located nitrogen application and nitrogen application after exhaustion, but the extent of increase of production reduced with increasing nitrogen application rate. At the nitrogen application rate of 300 kg/hm^2, the treatments of located nitrogen application and nitrogen application after exhaustion produced the highest rice yields, 10 514.95 kg/hm^2 and 10 472.36 kg/hm^2 , respectively. Rice plants lodged and yield decreased when the nitrogen application rate went even higher than that point. In both treatments of nitrogen application, the dry matter accumulation and nitrogen uptake of rice plants, as well as the soil total nitrogen content all increased, whereas the nitrogen use efficiency decreased with the increase of nitrogen application rate. There were no significant differences between the production indexes from the treatments of located nitrogen application and nitrogen application after exhaustion, indicating that these indexes were related to the seasonal nitrogen application rather than the background nitrogen level in the soil after one year of exhaustion.