将一粒水稻或小麦的种子种在田里，它会生根、发芽、分蘖和拔节，几个月后抽穗、结实。长出几十颗甚至更多的籽粒，整个植株干重常常增加上百倍。它究竟是靠什么长大的？许多人会这么回答：“庄稼一支花，全靠肥当家。这是由土壤中吸收养分长大的。”因为人们看到在肥沃的土壤 When a seed of rice or wheat is planted in the field, it will root, germinate, tiller and join, and after a few months, it will be heading and strong. Growing dozens or even more grains, the whole plant dry weight is often increased hundreds of times. What exactly is it growing up? Many will reply: “The flowers are all flowers, all by the fat heads, grown up by the nutrients in the soil.” Because people see it in fertile soil