Monoculture is growing a single crop in a large area. This is very common in modern agriculture, as it allows relatively few people to harvest large amounts. Monocultures have problems, however: It is easier for pests and diseases to spread in a monocultrure than when crop rotation is used. Growing the same crop also puts a strain on the soil, which may need to be fertilized to support a monoculture. Farmers who don't understand these problems may ruin their farm.