| 摘要: |
| 利用“差量法”研究了八种一年生豆类作物的固氮力,结果表明:花期后固氮率达60—70％,增施氮肥降低固氮率,增施磷肥提高固氮率。在瘠薄的土壤上,一年生豆类作物植株总氮量约1/3来自土壤,2/3来自空气;但地力高时则相反,2/3来自土壤,1/3来自空气;地力更高时,则全部来自土壤,即使氮磷合理配合,来自空气的最多不超过1/3。种植一年生豆类作物后,土壤氮量较种豆前减少,靠根茬氮的返还不能补偿这一亏损,表明种豆后的茬地土壤肥力有所降低,茬地后效生物学检验证实了这一结论。一年生豆类作物由于根瘤菌的共生固氮作用,固氮量可达10斤/亩以上。 |
| 关键词: 豆类作物,固氮率,差量法,茬地土壤肥力,氮返还率,生物固氮,生物学检验 |
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| N--fixing Capacity and After--effects of Annual Pulse Crops |
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Wang Liufang Wang Lixiang Fu Zengguang Fan Fangqiang Agronomy Department Northwestern Agricultural University
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| Abstract: |
| N--fixing capacity of annual pulse corps of 8 kinds were studied by means of "difference method".The results indicated that N-fxing rate reached 60-70％ after the flower stage,and that increasing application of N fertilizer decreased N-fixing rate,while increasing application of p fertilizer increased N-fixing capacity.In the poor soil,1/3 of total amount of N in annual pulse crops from it and 2/3 from the air.Conversely,in the rich soil,2/3 of total amount of N in annual pulse crops comes from it and 1/3 form the air.And even in the richer soil,total amount of N in annual pulse crops comes entirely from it.Even if there is a rational match of N and P,total amount of N in annual pulse crops doesn't surpass 1/3 at most.After annual pulse crops were planting.This N loss in the soil can not be compensated by relying on stubble nitrogen.This showed that the pulse stubble land fertility had some drops.The conclusion was confirmed by the biotic test of after-effect of the pulse stubble field.Thus,the amount of N fixed by symbiotic nodule forming bacteria can reach 75 kg/ha. |
| Key words: Pulse crops,difference method,N-fixing rate,soil fertility of stubble field,N-returning rate,biological N-fixation,biotic test |
