不断增加土壤的氮素含量是保证农业生产持续增长的条件之一.根据Burris 1977年概算全世界耕地中的氮素:化学固氮即人工施入的氮素化肥为4000万吨纯氮;生物固定的氮素为4400万吨,其中豆科作物的固氮量约占80%.目前全世界禾谷类作物占作物种植面积或总产量的绝大部分,如何使禾谷类作物也像豆科作物那样固定空气中的氮素,这是不少科学家长期探索的课题. Increasing the nitrogen content of soil is one of the conditions to ensure the continuous growth of agricultural production.According to Burris 1977 estimates of nitrogen in cultivated land around the world: chemical nitrogen fixation that is man-made nitrogen fertilizer is 40 million tons of pure nitrogen biological immobilization Of the nitrogen is 44 million tons, of which about 80% of the nitrogen fixation of leguminous crops.Currently the world cereal crops account for most of the acreage or total output, how to make cereal crops are also fixed as leguminous crops Nitrogen in the air, which is the subject of long-term exploration by many scientists.