闽北山垄田稻萍鱼共生体系与萍体氮素循环利用效率研究

STUDY ON "RICE-AZOLLA-FISH" CROPPING ECOSYSTEM AND EFFICIENCY OF AZOLLA NITROGEN IN THE VALLEY PADDY FIELD OF NORTHERN FUJIAN

将稻－萍－鱼共生体系的综合耕作技术引入山垄稻田。试验结果表明：山垄稻田中草鱼、尼罗罗非鱼以红萍为饵食，其鲜鱼产量分别达3568kg／hm2和3702kg／hm2;中稻和再生稻产量分别达5710～6006kg／hm2和3478～3772kg／hm2，比施化学氮肥处理区分别提高689．0～1132．5kg／hm2和458．4～658．9kg／hm2。15N试验结果显示：在稻萍鱼体系中鱼体和水稻对红萍氮总利用率达52．8％～57．9％．而施用化学氮肥处理区的水稻对氮素利用率仅为33．5％。连续两年实施稻萍鱼共生体系耕作技术．山垄田土壤有机质平均提高0．15％，且整个耕作体系病情指数下降42．1％～50．7％．减少农药施用量，有助于生态环境改善，达到增产增收的目的。

The cropping technology of 'rice- azolla- fish' ecosystem were applled intovalley paddy field. It was showed by the plot experiment that the grass fish and T.nilotica is 3568 and 3702kg/hm2 respectively, when the azolla was used as fish fodderin the valley paddy field. The yields of monocropping rice and the ratooning rice in theplot of 'rice -azolla-fish was 5710~6006kg/hm2 and 3478~ 3772kg/hm2, respectively,and they were higher as 689. 0 ~1132. 5kg /hm2 and 458. 4~ 658. 9kg /hm2 than thetreatment of applying chemical nitrogen fertilizer. It was showed that the totalefficiency of N-azolla is 52. 8%~57. 9% in the 'rice- azolla -fish'ecosystem and that only33. 5% in the treatment of applying chemical nitrogen ferti1izer by 15 N- tracingexperiment. The 'rice-azolla-fish' ecosystem had been applied for two years, the organicmatter in the soll from valley paddy field increased O. l5% and the index of diseasedecreased 42. 0% ~ 50. 7% in this cropping ecosystem. It was a good method forimproving eco-environment and reached to increasing both yield and income when thetechnblogy of cropplng ecosystem was applled successifully.