| environ. |
nitrogen fixation Assimilation of atmospheric nitrogen by a variety of microorganisms which live freely in soil. Once the nitrogen has been captured by one of the microorganisms, there are many different routes by which it is handled. Some is retained in the soil as decomposing plant matter, waiting to be released and taken up by new crops as a nitrate. That nitrate is produced by nitrifying bacteria living in the soil that thrive on ammonia, which is produced by decaying plant and animal material. In processing nitrogen the nitrifying bacteria produce nitrate that can be absorbed by the roots of plants (土壤里自由存在的多种微生物对大气中氮的吸收。一旦微生物已经捕获到氮，有很多不同的路线来处理。一些像分解的植物那样被保留在土壤里，等待作为硝酸盐被新的庄稼吸收。 硝酸盐是通过生活在土壤中的细菌硝化而产生的，靠氨旺盛生长，这些氨是由腐烂的植物和动物材料而产生的。) |
