For a long time, human beings mainly depended on agriculture for food and clothing. Since the beginning of slash-and-burn farming in ancient times, agriculture has always relied on a large number of human labor, and is restricted by various natural conditions, and its development is very slow. In the 19th century, the use of agricultural machinery gradually improved labor conditions. However, in agricultural production, the real increase in yield per unit area comes after the application of chemical fertilizers and pesticides. Practice has proved that the role of chemical fertilizers is 40% to 65% in various measures to increase agricultural production. On the basis of the vigorous development of petrochemical industry, the large-scale production of synthetic ammonia and urea makes the output of chemical fertilizer occupy a large proportion of chemical products. In 1985, the world's total output of chemical fertilizers reached about 140Mt, becoming one of the bulk chemical products. The development of nitrogen, phosphorus, potassium compound fertilizers and trace element fertilizers further meets the needs of different soil structures and different crops.
In the early days, humans adopted natural crop pests. It was not until the end of the 19th century, after the formation of the modern chemical industry, that Paris green (arsenic preparation) was used to kill potato beetles and Bordeaux mixture to control grape downy mildew, and agriculture began a new era of chemical control. In the 1940s, pesticides and herbicides such as organochlorine, organophosphorus, and phenoxyacetic acids were produced, which were widely used in agriculture, forestry, animal husbandry and public health. However, some pesticides in this generation have been banned by many countries due to their high residues and high toxicity, causing ecological pollution. Some new pesticides with high efficiency, low residue and low toxicity have been developed. Among them, pyrethroids (pyrethrum is a plant with insecticidal effect) are biomimetic pesticides. The dosage per mu is only a few grams, which does not pollute the environment and has been put into industrial production. In addition, biopesticides are one of the most active fields in pesticide research in the 21st century.
The application of plastic films (such as high-pressure polyethylene, linear low-density polyethylene, etc.) in modern agriculture for mulching or greenhouse seedlings can significantly increase crop yields and is being promoted on a large scale.