Which method is primarily focused on reducing the use of fertilizers?

The method primarily focused on reducing the use of fertilizers is extensive cultivation. This agricultural practice emphasizes utilizing larger land areas with lower inputs like fertilizers and pesticides, often relying more on natural soil fertility and crop rotation. Extensive cultivation typically involves growing crops in an environmentally sustainable manner, which encourages a balance between production and resource conservation.

In contrast, intensive cultivation usually involves maximizing crop yields on smaller plots of land with high inputs of fertilizers and other resources to achieve greater productivity. Hydroponics, while it allows for high-efficiency crop production without soil, often uses nutrient solutions that can include synthetic fertilizers, and grafting is a propagation technique aimed at improving plant characteristics rather than fertilizer usage. Thus, extensive cultivation best represents a strategy aimed at reducing reliance on fertilizers.