What are some agricultural strategies (forms of agriculture) that increase crop yield?

Whatever strategy or technology you use, the basic
principles to increase crop yield remain the same:

1. Give nutrients to the crop in the right amounts and in
the right time

2. Supply water to the crop in the right amounts and in
the right time as well (e.g., dry conditions are required for
fruiting)

3. Provide the required meteorological conditions for the
crop in terms of light, air temperature and humidity, and
even CO2 gas concentration.

4. Protect the crop against weeds, pests, and diseases, as
well as against physical damage such as from strong
winds, heavy rains, and grazing animals.

5. Protect the environment in which the crop is growing
such as controlling against soil erosion, waterlogging,
water loss, and pollution -- anything that can reduce soil
and plant fertility.

6. Adequate management practices to control, maintain,
and react to farm or field conditions.