When earth is rich it bids defiance to droughts, yields in abundance, and of the best quality. ~ American farmer and US President Thomas Jefferson
The effects of pesticides run deep. Herbicides reduce earthworm casting, which promotes soil health. The toxins damage earthworm fertility, and so hurt soil quality.
In a natural environment, topsoil builds via decaying plant matter and weathering rock. The soil is protected by erosion by growing plants.
In soil made vulnerable by agriculture, erosion reduces productivity by up to 65% per year.
The former prairie lands that constitute the US breadbasket have lost half of their topsoil after being farmed for a century. Soil is eroding 30 times faster than the natural formation rate.
It takes 500 years for Nature to replace an inch of topsoil. Reforming damaged topsoil to a depth for agriculture takes 3,000 years.
Food crops are much hungrier than the parsimonious grasses that once covered the Great Plains. Much of the soil there is now little more than a sponge into which synthetic fertilizers are poured to produce crops.
Erosion rates are rising throughout the world.
China is losing 36 tonnes of topsoil per hectare each year. During the spring planting season, Chinese soil can be found in the air as far away as Hawaii.
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China exceeded its capacity to feed itself by the late 1980s. The Chinese import prodigious quantities of grain while pushing their croplands to the limit with artificial fertilizers and pesticides to eke out what they can.
Agricultural productivity has declined in parts of Africa by 50% due to soil erosion and desertification. (8,000 years ago, agriculture and the introduction of livestock in North Africa culminated in the creation of the Sahara Desert, which had before been verdant land.) Production losses in the range of 20% have been reported in India, Pakistan, and several Middle Eastern countries, thanks to the farming practices advocated by Green Revolutionaries.
Contrary to the myth that industrialized agriculture is superior, studies have shown that indigenous natural systems are more efficient in terms of yields, labor, and energy.
Both from the point of view of food productivity and of food entitlements, industrial agriculture is deficient as compared to sustainable farming systems based on diversity and internal inputs. ~ Vandana Shiva
Further, agriculture reliant upon chemical fertilizers and pesticides is environmentally unsustainable: the toll on the soil and pollinators is too much for plants to bear.
All the great agricultural systems which have survived have made it their business never to deplete the earth of its fertility without at the same time beginning the process of restoration. ~ Albert Howard