Why is chemical fertilizer used in new farming methods? How could use of fertilizers make soil less fertile? What are the alternative ways of enriching soil?

Chemical fertilizers consist of Nitrogen, phosphorus, and potassium. Very important for the growth of the plant. They are used in large quantity by the farmers because they are nutrient specific and provide the required nutrients to the plant.
These fertilizers tend to make the soil less fertile because it depletes the soil of the hummus, which cannot be replenished in a very short time. It depletes the soil of its microorganisms which are essential for the growth of the plant. The farmers are usually unaware of the correct usage of these chemical fertilizers and tend to employ a large quantity of the same
The different ways by which soil can be enriched are
1. Crop rotation
2. Use of manures
3. If chemical fertilizers are being used, a proper check must be kept on the quantity and the quality.