应用~(15)N示踪研究棉麦(豆)两熟作物对氮素养分吸收利用

应用~(15)N 示踪法研究我省棉区棉、麦(豆)套种对氮肥合理施用中某些因子的影响。结果表明:在棉、麦套种栽培中,处于生育后期的小麦,对于麦行间施给棉花底肥、苗肥的氮素,仍能分别吸收利用17.5%和2.5%,而且所吸收的养分中,90%以上底肥氮和50%以上苗肥氮转运到穗部;在前茬小麦每亩施氮10斤的情况下,小麦因吸收了棉花底肥中的氮素而增产,但对当季棉花产量无明显影响;因所吸苗肥氮量很少,对小麦无增产作用。在棉豆(蚕豆)套种中,由于蚕豆的固氮作用,对棉花的底肥、苗肥吸收利用很少,仅为3.4%,是小麦吸收量的1/4,可见蚕豆基本不与棉花争氮。在后作棉花施用等量氮情况下,豆茬花(蚕豆不施肥)比麦茬花(小麦每亩施氮10斤)平均增产9.17%。本文还阐述了麦棉两熟中,前后作施肥的相互影响。

THE ABSORPTION AND UTILIZATION OF N-NUTRIENT BY CROPS IN COTTON-WHEAT OR BROAD BEAN DOUBLE CROPPING SYSTEM

The effects of some factors on the utilization of N-fertilizer by crops in cotton-wheat or broad bean interplanting system in southern China were studied by using ~(15)N tracing technique. The results showed that,in cotton-wheat interplanting system even in the late growing stage,the wheat could still absorb 17.5% and 2.5% of N-fertilizer applied to cotton as basal dressing and top dressing in seedl- ing stage respectively.Up to 99% of the absorbed N from base fertilizer was transported to the ears of wheat,and made yield increase of wheat by about 8%.But there was no significant influence on the yield of cott- on.Up to 54% of N absorbed from top dressed fertilizer was transported to wheat ears,but didn't make yield increase. In cotton-broad bean interplanting system,owing to N-fixing ability of leguminous plant,the broad bean only absorbed 3.40% of the N-fertilizer applied to cotton as basal and top dressing in seedling stage.It is only 1/4 of the amount of N absorbed by wheat.Therefore there is no competition of absorbing fertilizer N between broad bean and cotton plant.Moreover, the yield of cotton was increased by 9.2% when broad bean,instead of wheat,wesoplonted as pre-crop of cotton. The mutual influence of wheat and cotton as pre-crop and succeeding crops on N fertilization in interplanting system was also expounded on th- is report.