Petrochemical fertilizers and pesticides destroying farmlands
Traditional farming relied on the planting of diversified crops that attracted a range of insects, some of which are natural enemies of insect pests. Eliminating crop diversity in favor of monoculture crops left the fields without the beneficial insects, and crops became more vulnerable to insect pests, requiring a steady rise in the use of pesticides. Much of the sprayed pesticide runs off into the groundwater and becomes a major source of water pollution in every agricultural region of the world.
The pesticides also destroy the remaining soil. The soil contains millions of microscopic bacteria, fungi, algae, and protozoa, as well as worms and anthropods. These organisms maintain the fertility and structure of the soil. Pesticides destroy these organisms and their complex habitats, hastening the process of soil depletion and erosion. American farms lose more than four billion tons of topsoil annually, much of it because of the high-tech farming practices introduced over the past half century. By the 1970s, the U.S. had lost more than one-third of its agricultural topsoil. The depletion and erosion, in turn, have required the use of ever-increasing amounts of petrochemical fertilizers to maintain agricultural output. Marginal returns have set in. More and more energy inputs are required to produce smaller gains in net energy yield...
Moreover, high energy agriculture is now a major contributor to global warming. ..reliance on petrochemical fertilizers has increased the release of nitrous oxide, a potent global warming gas.
The Hydrogen Economy, Jeremy Rifkin