5.9 Environmental Impacts of Agricultural Practices

Land Modification & Irrigation

Agriculture reshapes environments through practices like irrigation, terracing, and drainage. Irrigation boosts yields in dry regions but can cause salinization (salt buildup) and aquifer depletion (e.g., Ogallala Aquifer). Draining wetlands for farmland destroys habitats and reduces natural water filtration, while terracing helps control erosion on slopes.

Deforestation & Desertification

Clearing forests for farmland or grazing causes deforestation, losing biodiversity and increasing carbon emissions. Overgrazing and poor land management in semi-arid areas cause desertification, turning productive land into desert. Slash-and-burn (swidden) agriculture can be sustainable at low population densities but degrades soil when overused.

Chemical Inputs & Pollution

The Green Revolution increased yields using fertilizers, pesticides, and HYV seeds, but caused water pollution via runoff, eutrophication (algal blooms from nutrient overload), and soil degradation. Pesticides can harm pollinators and enter food chains through biomagnification. Overgrazing and monocropping also deplete soil nutrients and reduce biodiversity.

Key terms

Salinization

Buildup of salts in soil from repeated irrigation and evaporation, reducing fertility.

Desertification

Degradation of semi-arid land into desert due to overgrazing, deforestation, and drought.

Eutrophication

Nutrient runoff (from fertilizers) causing excessive algae growth and oxygen depletion in water.

Slash-and-burn (swidden) agriculture

Clearing and burning vegetation to farm; sustainable at low density, harmful with shortened fallow periods.

Green Revolution environmental cost

Increased crop yields via chemical fertilizers/pesticides and HYV seeds, but caused pollution and soil degradation.

Try an AP-style question

Desertification is often caused by…

1. urban growth only
2. overgrazing and deforestation
3. cold climates
4. too much rain