Seed must be purchased. Dense stands of crop require more water. Changes in land use, crop cultivation on unsuitable land, leads to soil salinity, erosion. Loss of plant resistance to pathogens, leads to dependence on chemical pesticides. Costs of providing irrigation.
Effects vary in different countries.
Application of these techniques to new crops holds great promise for increasing and improving food supply. Some concern that large multi-national corporations will monopolize development, reap most rewards.