Final answer:
The control group in the corn fertilization experiment is the one not receiving any fertilizers, providing a baseline for measuring the effects of the natural fertilizers tested.
Step-by-step explanation:
In an experiment where four groups of corn are given different types of natural fertilizer, the group that is not receiving any fertilizer serves as the control group.
This control group is essential for establishing a baseline for comparison against other groups that are receiving some form of intervention—in this case, the various natural fertilizers like fish emulsion, worm castings, and cow manure compost.
In scientific experiments, the control group is used to measure the effect of the variable being tested, which in this scenario is the type of natural fertilizer. The outcome of interest here might be the height of corn plants or the amount of water they consume, with observations that aim to discern how these factors are influenced by the use of natural fertilizers versus none at all.