Carbon (C) is responsible for all life on earth. Carbon dioxide (CO2) released into the atmosphere is recycled endlessly as part of the carbon cycle. Plants take CO2 from the air and use the C for energy, helping to build essential biological compounds such as carbohydrates and proteins.
Converted through photosynthesis into simple sugars, C helps plants build starches, carbohydrates, cellulose, lignin and protein.
Crop residues, green manures and animal wastes can be significant sources of organic C in the soil.