Diversity can be added both in time, as with a crop rotation or sequence, or in space, with a polyculture or intercropping (see table below).
This can lead to an increased dependency and reliance on expensive machinery that cannot be produced locally and may need to be financed.
This can make a significant change in the economics of farming in regions that are accustomed to self-sufficiency in agricultural production.
The controversies surrounding monocropping are complex, but traditionally the core issues concern the balance between its advantages in increasing short-term food production—especially in hunger-prone regions—and its disadvantages with respect to long-term land stewardship and the fostering of local economic independence and ecological sustainability.
For example, a well-known concern is pesticides and fertilizers seeping into surrounding soil and groundwater from extensive monocropped acreage in the U.S. and abroad.
Journalist Michael Pollan argues that monocropping not only depletes fertile land, but it results in overproduction of certain agricultural crops.
While economically a very efficient system, allowing for specialization in equipment and crop production, monocropping is also controversial, as it damages the soil ecology (including depletion or reduction in diversity of soil nutrients) and provide an unbuffered niche for parasitic species, increasing crop vulnerability to opportunistic insects, plants, and microorganisms.