Question: In the book How the world really works by Vaclav Smill, This chemical element is essential to plant life, as it is a component of chlorophyll, DNA/RNA, and proteins. Naturally it cycles out of the atmosphere with the help of lightning and rain, and it also can be made chemically available to plants by soil bacteria that live on the roots of certain types of plants or through the waste products of animal digestion. Modern synthetic fertilizer, though, is based on energy-intensive methods developed during the early 20th century. Group of answer choices calcium nitrogen hydrogen oxygen carbon. Need Assignment Help?