关键词: 低地力, 油菜（Brassica napus L.）, 直播, 移栽, 氮肥用量, 产量, 经济效益

Abstract: To investigate nitrogen application effects and suitable N application rate of direct-sowing and transplanting rapeseed （Brassica napus L.） under low soil fertility condition,8 different N levels （0,45,90,135,180,225,270 and 360 kg/hm²） were set,and the effects of N application rates on rapeseed yield and economic benefit were studied under direct-sowing and transplanting. The results showed that,under low soil fertility condition,the yield of direct-sowing and transplanting rapeseed without N fertilizer were only 140 kg/hm² and 613 kg/hm²,respectively; the maximum yields were reached when N application rates were 206.0 kg/hm² and 249.2 kg/hm²,respectively, and the maximum yields were 2 525 kg/hm² and 2 899 kg/hm²,respectively.The output value and net profit of direct-sowing and transplanting rapeseed were significantly increased by N fertilization and no longer increased when the nitrogen application rate exceeded 270 kg/hm². The output value of direct-sowing rapeseed decreased by 1 347 yuan/hm² on average compared with transplanting rapeseed, but the net profit was increased by 482 CNY/hm². Direct-sowing rape could save 43.2 kg/hm² N fertilizer and increased net profit up to 972 CNY/hm² under low soil fertility condition.

Key words: low soil fertility, rapeseed（Brassica napus L.）, direct-sowing, transplanting, N application rate, yield, economic benefit