You perform an experiment in which you take 16 pots (same si…
You perform an experiment in which you take 16 pots (same size) of strawberry plants and give half of them 10 ml of nitrogen supplement per liter of water and the other half receive only water. Each group is then exposed to 16 hours of light each day. You monitor the height of the plants for 4 weeks. You observe that plants given nitrogen supplement grow taller than plants grown with no nitrogen supplement. What is the independent (experimental) variable in this experiment?