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在陕北黄绵土设置微区试验,研究苜蓿一根瘤菌共生固氮量.结果表明,用同位素~(15)N法测出的共生固氮总量为9.36～18.72kg/亩,平均为13.59kg/亩,固氮量占苜蓿总需氮量的73%.而用全氮差异法测出的固氮量比~(15)N法测出值约小1/2～1/3.
A micro-experiment was conducted on loessial soil in northern Shaanxi to study the symbiotic nitrogen fixation of a strain of alfalfa.The results showed that the total amount of symbiotic nitrogen fixation measured by isotope ~ (15) N method was 9.36 ~ 18.72kg / mu with an average of 13.59kg / mu , And the amount of nitrogen fixation accounts for 73% of the total nitrogen requirement of alfalfa, while the nitrogen fixation amount determined by total nitrogen difference method is smaller than that of ~ (15) N method by about 1/2 ~ 1/3.