These can improve harvests, reduce disease and help with pest control by attracting helpful insects. For example, some kinds of bacteria in soil take nitrogen from the air and make it into a form that plants can use.这可以提高产量，减少疾病，通过吸引有益昆虫来控制虫害。比如说，有的细菌能吸收空气中的氮，将之转化为植物可使用的形式。_______________________________________________.
