玉米大豆混作系统氮素转移特性的研究

在不同氮水平土壤上用１５Ｎ同位素稀释法对玉米大豆混作系统氮素转移特性进行了研究。结果表明，低氮和高氮土壤上均发生了固氮产物的转移。低氮土壤混作玉米从大豆固氮产物中获得１４．９４％～２６．９６％的氮，在高氮土壤上仅获得２．５６％～２１．１３％的氮；混作大豆固氮率的提高率，低氮土壤为—１０．３６％～—２１．１４％，高氮土壤为２９．１０％～３２．６９％；混作玉米和混作大豆的植株含氮量，在低氮土壤中均比单作降低，而在高氮土壤上则有不同程度的提高。玉米大豆混作系统在低氮土壤上主要消耗土壤速效氮，在高氮土壤上主要消耗土壤全氮。

Characteristics of Nitrogen Transfer from Soybean to Maize in Mixcropping Systems

The study on the characteristics of nitrogen transfer from soybean to maize in miscropping systems was carried out in soils with various nitrogen level in 1992 and 1993 by the 15N isotope dilution method. Nitrogen transfer took place in soils with both low and high nitrogen levels. 14. 94- 26. 97% of nitrogen in maize plants were transferred from the N2-fixed products in soybean plants in low nitrogen level soils,while 2. 56 - 21. 13 % in high level nitrogen soils. Increasing percents of the N2-fixation in soybean were - 10. 36- 21.14 % and 29. 10- 32. 69% respectively in low and high nitrogen soils in mixcropping as compared with monocropping. Nitrogen contents in maize and soybean plants were decreased by 17. 31 - 39.35% and 10. 63- 18. 44% and increased by 12. 35- 29. 71 % and 8. 21- 8. 99% respectively in low and high nitrogen soils in mixcropping as compared with monocropping. Rapidly available and total nitrogens were consumed respectively in low and high nitrogen soils in maize and soybean mixcropping system.