Afarmer divided his piece of land into 2 equivalent groups and the quality of the soil is the same in both of these groups. he used fertilizers for the first group of land. he did not use fertilizers for the second group of land. at the end of the season, he measured the yield of the crops in these 2 groups. is the study observational or experimental? if it is an experiment, what is the controlled factor?

Experimental, the controlled factor is the fertilizer

Step-by-step explanation:

It is an experimental study since the researcher has control over the variables (fertilizer in one but no in the other) compared to observational study where the researcher does not have control over the variables. In addition, it is experimental because the research is studying the effect of the fertilizer on the crop yield by adding fertilizer to one soil but not adding to another quantity of the same soil with the same quality except for the fertilizer. He then measures the outcome or effects.