Monoculture is the practice of growing one crop over a large area, season after season or in a single continuous block. A thousand hectares of maize in Iowa is a monoculture. So is a golf-course lawn or a pine plantation.

The approach has clear advantages at scale. A single crop can be planted, sprayed, and harvested with the same machinery and the same schedule. It simplifies decisions, cuts costs, and has helped drive the yield gains of the past century. Most of the world's wheat, rice, maize, and soybean come from monoculture systems.

The costs

• Pests and diseases build up when the same host is always present
• Soil nutrients deplete unevenly without rotation
• Biodiversity drops sharply above and below ground
• Weather shocks hit the whole crop at once

Growers push back with crop rotation, resistant varieties, and targeted pesticides. But the fundamental vulnerability remains. A single hail storm or a new pathogen can take an entire season's income in a monoculture in a way it would not in a diverse system.