Probably made of:
Oxygen ----------  43kg
Carbon ----------  16kg
Hydrogen --------  7kg
Nitrogen -------  1.8kg
Calcium ----------  1kg
Phosphorus -  0.78kg
Potassium ---  0.14kg
Sulfur ---------  0.14kg 
Sodium -------  0.10kg
Chlorine  ----  0.095kg
Magnesium - 0.019kg