Chemistry – Organic and Biochemistry – Everyday Matter
For millennia humans have been governed by simple truths. Food will spoil and be consumed by pests while people will die and suffer from disease.
It is a natural part of the human condition to strive to control the forces of nature with technology, so for that reason we have developed pesticides to protect our crops, and medicines to cure and fight disease.
These improvements benefit our surroundings as we try to enhance the quality of our lives.
Earth Science: Chemistry – Organic and Biochemistry – Chemistry and Nutrition
Artificial fertilizers and pesticides are necessary to produce enough food for the Earth’s growing population. We also need better distribution of food and manufactured preservatives to reduce food waste.
The use of artificial fertilizers began in 1850. Today, a farmer can produce five times as much corn (maize) on an acre of land as his counterpart could have in the mid- 19th century. This extraordinary revolution started when the German chemist Justus von Liebig discovered that plants extract nutrients from the soil and that these nutrients are then unavailable for use by future plants.
To maintain agricultural output, the extracted nutrients-especially nitrogen, phosphorus, and potassium- must be returned to the soil. This is the role of fertilizers. Today, chemically generated fertilizers are designed for each crop based on its specific nutritional requirements.
For example, the fertilizers used for corn are different from those used for wheat or soybeans. Modern fertilizers include calcium, magnesium, sulfur, and sometimes trace elements that play an important role in nutrition for specific plants.
Pest control
Fertilizers are not solely responsible for the huge increase in agricultural production. Advances in pest and disease control have also played an important role. Starting in the second half of the 19th century, farmers turned to chemical compounds to fight crop-threatening organisms. For example, Victorian era farmers used the “Bordeaux mixture” (burnt lime in a copper sulfate solution) to fight fungal diseases.
In the 1940s, it was discovered that chlorinated hydrocarbons and organic phosphorus compounds could efficiently kill insects. Herbicides were found that suppressed the weeds and grasses, which were consuming light, water, and nutrients that would otherwise be available to crops. New pesticides are constantly under development.
This is necessary because fungi and insects gradually become resistant or insensitive to the old ones. In addition, the chemical controls currently being developed are becoming increasingly efficient. Years ago, a farmer might have used 11 pounds (5 kg) of pesticides on an acre of crops, while today a farmer can achieve the same amount of pest control with only 3.5 ounces (100 g) of chemicals.
Preservatives
In earlier times, when fungi and rot often spoiled food, famine was common. Today, substances are used to reduce the growth of fungi and repel insects, enabling food to be stored for a longer time.
Commonly used preservatives include sorbic acid, nitrites, vitamin C, and vitamin E, which prevent the multiplication of pathogens. However, there is debate today about the possible negative effects of such additives.
HOW PESTICIDES WORK
Pesticides are chemical or biological agents that are used alone or as a mixture against organisms considered pests in agriculture and forestry. They range from protective products to substances for eradication of pest organisms in the widest sense.
The best-known of these are insecticides against insects, herbicides for weed control, and fungicides against fungi and fungal diseases. Many pesticides are also toxic to humans; therefore, protective suits are usually worn during large scale agricultural applications.
Chemical residue from pesticides in food items is particularly significant as a health concern for humans. For this reason, limits have been set for residual levels in both food for humans and animal feed, which must not be exceeded.