How is experiment different from observation?

Observation and experiment are methods of biological research.
Observation is the study of living organisms in their natural habitat. For example, the study of the regularities of the growing season in a plant in a given region, which allows us to draw conclusions about the advisability of its selection.
The experiment involves changing conditions and observing the reaction of the body. For example, the study of the response of a given plant species to different amounts of applied nitrogen fertilizers, which allows you to determine the optimal dose.