中文摘要：

通过2010—2013年的大田试验,探讨了2个施氮水平（300和525 kg·hm^-2）和3种种植模式（甘蔗、大豆单作及甘蔗-大豆1∶2间作）对蔗田大豆固氮、甘蔗和大豆氮素累积及氨挥发和氮淋溶的影响.结果表明：与大豆单作相比,甘蔗-大豆间作的大豆固氮效率下降,但不同施氮水平间作模式之间无显著差异.不同施氮水平和种植模式对甘蔗、大豆氮素累积无显著影响.减量施氮水平下氨挥发量低于常规施氮处理,不同施氮水平和种植模式对氮淋溶量无显著影响.除2011年甘蔗单作减量施氮水平下出现蔗田氮素亏缺（-66.22 kg·hm^-2）外,其余不同年份不同种植模式下氮素都处于盈余状态（73.10-400.03 kg·hm^-2）,施氮水平显著影响了蔗田的氮素盈亏,且常规施氮水平下氮素盈余量显著高于减量施氮处理,过高的氮素盈余增加了氮素污染农田环境的风险.从培肥地力、降低氮素污染环境的风险和节约生产成本等方面考虑,减量施氮水平下甘蔗-大豆间作模式具有一定的生态合理性.

英文摘要：

A four-year（ 2010-2013） field experiment was carried out to explore the effects of three planting patterns（ sugarcane,soybean monoculture and sugarcane-soybean 1： 2 intercropping） with two nitrogen input levels（ 300 and 525 kg · hm^-2） on soybean nitrogen fixation,sugarcane and soybean nitrogen accumulation,and ammonia volatilization and nitrogen leaching in sugarcane field.The results showed that the soybean nitrogen fixation efficiency（ NFE） of sugarcane-soybean intercropping was lower than that of soybean monoculture. There was no significant difference in NFE among the treatments with the two nitrogen application rates. The nitrogen application rate and intercropping did not remarkably affect nitrogen accumulation of sugarcane and soybean. The ammonia volatilization of the reduced nitrogen input treatment was significantly lower than that of the conventional nitrogen input treatment. Furthermore,there was no significant difference in nitrogen leaching at different nitrogen input levels and among different planting patterns. The sugarcane field nitrogen balance analysis indicated that the nitrogen application rate dominated the nitrogen budget of sugarcane field. During the four-year experiment,all treatments leaved a nitrogen surplus（ from 73.10 to400.03 kg·hm^-2）,except a nitrogen deficit of 66.22 kg·hm^-2in 2011 in the treatment of sugarcane monoculture with the reduced nitrogen application. The excessive nitrogen surplus might increase the risk of nitrogen pollution in the field. In conclusion,sugarcane- soybean intercropping with reduced nitrogen application is feasible to practice in consideration of enriching the soil fertility,reducing nitrogen pollution and saving production cost in sugarcane field.