What is an example of a main method used in sustainable agriculture?

Alley-cropping is indeed a main method used in sustainable agriculture because it promotes biodiversity, improves soil structure, and enhances crop productivity. This practice involves planting rows of trees or shrubs alongside crops, which provides multiple benefits. The trees can offer shade, reduce soil erosion, and increase organic matter as their leaves decompose, enriching the soil with nutrients.

In addition to these ecological benefits, alley-cropping can help create a more resilient agricultural system by diversifying the types of plants grown in a single area. This diversification can protect against pests and diseases, while also maximizing the efficient use of resources such as sunlight, water, and nutrients.

The other methods listed do not align with sustainable practices. For instance, clear-cutting often leads to deforestation and loss of biodiversity, intensive tillage can degrade soil health, and while hydroponics is efficient in resource use, it typically relies on controlled environments that might not be suitable or accessible for all farming contexts.