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利用同位素示踪技术研究不同施肥处理对黑麦草单播及黑麦草与白三叶混播条件下不同时期牧草茎叶N %与对白三叶的共生固氮的影响。结果表明 :( 1 )混播或单播黑麦草的N %在施肥后 67d达到最高值 ,其后随时间的推移逐渐降低 ;( 2 )混播白三叶的N %在施肥后 67d达到最高 ,随后稍有降低 ,其后又有所增加 ,这与白三叶固氮活性逐步提高有关 ;( 3 )施N水平较低时 ( 1 64kg硫铵 /hm2 ) ,不同时期刈割的混播黑麦草的N %均高于单播黑麦草的N % ,显然是由于白三叶共生固氮所产生的N素为黑麦草提供了新的氮源 ;( 4 )混播白三叶中N素的主要来源是共生固氮 ,混播黑麦草和单播黑麦草中N素的主要来源是土壤 ;( 5)施N处理对黑麦草和白三叶N %的影响差异显著。
The effects of different fertilization treatments on symbiotic nitrogen fixation of rye grass and white clover under different fertilization conditions were studied. The results showed that: (1) N% of mixed or uniaxial ryegrass reached its highest value at 67 days after fertilization, then gradually decreased with the passage of time; (2) N% of mixed white clover reached the highest level at 67 days after fertilization, Slightly decreased and then increased, which is related to the gradual increase of nitrogen fixation activity of white clover. (3) When the N level was low (1 64 kg ammonium sulfate / hm2), the N % Is higher than that of unicceed ryegrass, apparently due to the fact that N produced by symbiotic nitrogen fixation of white clover provides a new source of nitrogen for ryegrass. (4) The main source of N in mixed clover is symbiosis The main source of nitrogen in nitrogen fixation, mixed sowing and single sowing of ryegrass was soil. (5) The effects of N treatment on N% of ryegrass and white clover were significant different.