Why can clearing tropical forests for farming cause nutrient loss from soil?

Clearing tropical forests for farming leads to nutrient loss primarily because these ecosystems possess inherently infertile soils. In a healthy tropical rainforest, a large proportion of essential mineral nutrients is stored within the living vegetation itself rather than in the soil.12

When forests are cleared, this cycle is disrupted in several ways:

• Leaching: Because tropical regions experience high levels of precipitation, water constantly moves downward through the soil profile. Without the forest canopy and root systems to intercept and recycle nutrients, these minerals are leached out of the soil and into streams and rivers, leaving the ground relatively infertile.1
• Loss of Organic Input: In undisturbed forests, nutrients are replenished in the uppermost soil layers through the decomposition of fallen leaves and organic litter. Removing the forest eliminates this vital source of nutrient renewal.12
• Erosion: Once the protective cover of trees is removed, the heavy rainfall characteristic of the tropics washes away the topsoil, which contains the limited nutrients necessary to sustain plant growth.2

Consequently, land cleared for agriculture often becomes unproductive after only a few years of cultivation.32