对土壤中的矿物氮用其同位素~(15)N进行标记后,种上固氮作物,进行同位素稀释技术的应用研究。正常情况下,将固氮植株和作对照的非固氮植株同种于一块已标记过的土地上,对照株中~(15)N的富积量应与固氮株从土壤中摄取富积的量一致。在此情况下,固氮株从空气中吸收的非标记氮所占的比例,即生物固氮量,与从标记土壤中吸收的氮的富积稀释度成一定的比例关系。 After mineral nitrogen in the soil was labeled with its isotope ~ (15) N, nitrogen fixation was applied to study the application of isotope dilution technique. Under normal circumstances, the nitrogen fixation plants and control non-nitrogen-fixing plants on the same piece of land has been marked, the control plant ~ (15) N enrichment should be consistent with the amount of nitrogen-fixing plant from the soil uptake enrichment . In this case, the proportion of non-labeled nitrogen absorbed by the nitrogen fixing plant in the air, ie, the amount of biological nitrogen fixation, is proportional to the concentration dilution of nitrogen absorbed from the labeled soil.