Agricultural chemistry

Definition:Agricultural chemistry is an interdisciplinary applied science that looks at the chemical processes that affect vegetable and animal food production, food protection, and food-yield optimization. The goal of agricultural chemistry is to understand the chemistry of crop and livestock production in order to safeguard and improve it for human uses. Important applications are the development and enhancement of fertilizers to accelerate production and increase yields; the development and enhancement of crop protection via chemical pesticides, herbicides, and fungicides; and the development of genetically modified crop varieties with improvements such as higher yields and nutritional value and greater resistance to pests, herbicides, and drought. Agricultural chemistry is essential to meet the food needs of the growing human population.

Basic Principles

The idea to improve plant growth and yield by using a variety of fertilizers, ranging from animal and human dung to Nile mud, for example, is almost as old as agriculture. Similarly, some of the earliest pesticides used were sulfur and arsenic in European antiquity. In this sense, humans intuitively used agricultural chemistry long before it would be understood as a science.

Modern agricultural chemistry began in Europe in the middle of the eighteenth century. Scottish physician Francis Home introduced the idea in his Principles of Agriculture and Vegetation (1757). This was followed up by English chemist Humphry Davy in Elements of Agricultural Chemistry (1815). German chemist Justus von Liebig is generally considered founder of industrial agricultural chemistry. His Agrikulturchemie (1840; Chemistry in its Application to Agriculture and Physiology, 1847) presented the principle of industrially fabricated fertilizers. Its adoption caused a quantum leap in European agricultural production.

The development, manufacture, and continuous improvement of fertilizers as means to improve crop yield are the basic tasks of agricultural chemistry. Agricultural chemists have been instrumental in developing synthetic fertilizers and understanding and improving their effects. Great progress was made in the early part of the twentieth century on the basis of ammonium nitrate and ammonium sulfate. However, by the late twentieth century it was increasingly recognized that fertilizers contributed significantly to pollution, so there was a push to develop more environmentally friendly options that could still improve yields.

Development of effective crop protection—namely pesticides, fungicides, herbicides, and insecticides—is another important task of agricultural chemistry. After World War II, development of effective pesticides in tandem with new fertilizers triggered the so-called green revolution, which vastly increased global food production. There was again backlash, however, after the harmful environmental effects and human health impacts of widespread pesticide use became apparent. The development of safer crop protection methods became a major goal of many agricultural chemists.

Meanwhile, agricultural chemistry designed new hybrid plant seeds that provided higher yields at harvest. Further research led to creation of genetically modified foods and crop seeds, which have been sold commercially since 1996. Here, agricultural chemists have altered the genetic structure of some common crops, such as potatoes, corn, and soybeans, to create new plant varieties that offer higher yields, are more resistant to pests, and can provide extra nutrients. However, genetically modified foods have remained controversial due to fears about their safety, their ecological and environmental impact, and the fact that they are often considered the intellectual property of the companies that create them.

Other basic goals of agricultural chemistry include efforts to produce relevant products at as low a cost as possible, leading to lower food prices. Developing feed supplements in plants used as animal fodder and identifying optimized soil, water, and air conditions for plant growth are also important.

Core Concepts

Agricultural chemistry is based on scientific understanding of plant and animal physiology. With this foundation, agricultural chemistry analyzes how certain chemical molecules and compounds can affect crop and livestock growth, plant yield, and resistance to infection or predators. The impact of soil, water, and air conditions on crops is analyzed. A key task of agricultural chemistry is to develop increasingly effective ways of applying beneficial chemical compounds that guide crop growth and boost resistance to outside threats with as little cost and negative environmental effects as possible. Since the late 1980s, genetics and genetic engineering have become very important for modifying crops at the microbiological level.

Plant and Animal Physiology. These two scientific fields provide knowledge of the functioning of plant and animal organisms down to the cellular and molecular level. Of special importance are the biochemical processes in plants, which are studied in phytochemistry, and a plant’s power to resist infection, which is studied in phytopathology. Contemporary research focuses on the study of the chemical and biological processes at the level of plant cells and the interactions among these cells. How plants govern their internal functions and how they relate to their environment is researched as well. To carry out these studies, analytical and experimental tools from physics and chemistry are used. Animal physiology is used to analyze how animals convert plant feed and study the functioning of animal organisms from the molecular level upward.

Soil Sciences. The study of soil is important because it concerns a major influence on plant growth and strength. Through soil samples and remote sensing, soil is analyzed and classified with regard to its physical, chemical, and biological qualities. These in turn affect soil’s fertility and various levels of plant-growth support. In addition, the water and climate conditions of specific regions are studied for their effect on vegetation and determination of crop options.

Analytical Chemistry. The tools of analytical chemistry are applied to understand the processes of growth and survival in plant and animal organisms. Classic tools include the separation of chemical compounds by distillation, extraction, or precipitation and their subsequent qualitative and quantitative analysis. Instrumental chemical analysis uses continuously optimized instruments to measure the physical qualities of a chemical compound. Spectroscopy, mass spectrometry, and chromatography, as well as electrochemical and thermal analysis, are contemporary tools that are used in agricultural chemistry to gain knowledge both of plant and animal organisms and the properties of chemical compounds developed to influence their behavior.

Chemical Research and Development. A core task of agricultural chemistry is research into the development of new beneficial chemical compounds to support enhanced food growth and security. Standard chemical-research methods are applied, first in the laboratory and then with an eye on industrial-scale production. New products are tested thoroughly during the development phase, which also involves incorporation of knowledge gained from human toxicology to avoid any harmful side effects for humans.

Industrial Production and Chemical Product Engineering. Production of agrochemicals uses methods for aligning chemical reactions with industrial chemical production, where there is an emphasis on economies of scale and cost efficiency. The methods of chemical product engineering also affect agricultural chemistry. Here, principles of unit operation, chemical process design, and transport phenomena are employed to design a process for manufacturing industrial agrochemicals.

Genetics and Genetic Engineering. Humanity has made intuitive use of the consequences of genetics since the prehistoric development of agriculture and animal husbandry. This was previously done through selective breeding and crossbreeding to obtain plants and animals with desirable traits. In contemporary agricultural chemistry, genetic engineering has become a major focus of research and development. Genetic engineering mimics the naturally occurring gene transfer but controls it more closely by directly adding or deleting specific genes in an organism. This first became commercially feasible for plant modification in the 1980s and soon became a major focus of the agricultural industry.

Biosafety. Because of the inherent dangers of chemically manipulating human food and animal feed, biosafety is a very important concern in agricultural chemistry. Biosafety seeks to prevent a major loss of biological diversity, which could occur through the massive spread of alien or transgenic genes, particularly those associated with genetically modified food crops. The Cartagena Protocol on Biosafety provides scientific guidelines and rules that went into effect in 2003. At American universities and research institutes, a committee on biosafety evaluates and must approve agricultural chemistry research and experiments that may create a biohazard.

Applications Past and Present

Fertilizers. One of the oldest applications of agricultural chemistry is fertilizers to accelerate and increase plant growth and yield. They were used long before the science behind them was discovered.

The major breakthrough in scientifically understanding fertilizers was made by Justus von Liebig in 1840. Liebig discovered that nitrogen is an essential element of plant nutrition and that nitrogen-rich fertilizers can vastly improve plant growth. He propagated the use of ammonia and of chemical, rather than natural, fertilizers. Liebig found that plants require and thrive on phosphate, which they absorb best through the compound superphosphate (monocalcium phosphate). He sought to develop means of industrially producing such mineral fertilizers.

Liebig’s scientific discoveries led to the industrial production of fertilizers. In 1842, English agricultural scientist John Bennet Lawes patented his process of obtaining superphosphate from phosphates in rock and coprolite (fossilized dinosaur feces) and set up a factory for its manufacture. In 1843, Lawes founded the Rothamsted Experimental Station, devoted to scientific study of fertilizers and other issues in agricultural science. In the twenty-first century, the institution still operates as Rothamsted Research.

More factories producing industrial fertilizers in England and Germany in the 1840s and 1850s greatly increased agricultural production in Europe and, soon, the United States. As their value as natural fertilizers became understood, guano (excrement of sea birds and bats deposited on lime rock) and sodium nitrate were also widely used.

To lessen dependence on natural fertilizers, European scientists looked at more chemical alternatives. In 1902, ethnic German chemist Wilhelm Ostwald patented the Ostwald process of producing nitric acid, an important feedstock for synthetic fertilizers, from ammonia. In 1903, Norwegian scientist Kristian Birkeland patented a method of producing nitric acid from nitrogen in the atmosphere and then using it to manufacture synthetic fertilizers. This method, known as the Birkeland-Eyde process, consumed a great deal of energy.

In 1909, German chemist Fritz Haber succeeded in obtaining ammonia from atmospheric nitrogen through its reaction with hydrogen gained from methane. In 1913, Haber collaborated with fellow German chemist and engineer Carl Bosch at Germany’s BASF chemical company. They developed the Haber-Bosch process for industrial-scale production of ammonia. This finally provided sufficient feedstock for production of nitric acid under the Ostwald process. From this nitric acid, final nitrogen fertilizers were manufactured.

After these core chemical advances and discoveries, agricultural chemists began to devote their energies to creating fertilizers that would carry the desired nutrients to plants in most effective and concentrated form. To make fertilizers as environmentally friendly as possible, there has also been a drive to eliminate contamination, such as traces of cadmium or uranium, in less and less expensive processes.

Besides nitrogen, phosphorus and potassium are the most common industrial inorganic fertilizers. There was also a renaissance of organic fertilizers, and agricultural chemists sought to improve on their yield and production costs. The field of fertilizers has remained a primary application of agricultural chemistry.

Crop Protection. As with fertilizers, humans used pesticides long before their chemical and biological qualities were understood scientifically. In the eighteenth and nineteenth centuries in Europe and North America, scientists used plant extracts as insecticides, precursors to synthetic pesticides.

Chemical pesticides were discovered at the end of the nineteenth century. The first was dinitrocresol, invented by German chemical company Bayer in 1892. Since 1934, it has also been used as herbicide.

The 1930s were considered the golden age of pesticide discovery. In 1939, Swiss chemist Paul Hermann Müller, working for the Swiss pharmaceutical and chemical company Geigy, discovered the tremendous insecticide power of DDT (dichlorodiphenyltrichloroethane). DDT was used widely around the globe, with Müller receiving the 1948 Nobel Prize in Physiology or Medicine for his discovery. However, by the 1960s, DDT’s severe environmental side effects became known, particularly its role in damaging eggshells of fish-eating birds, including the American bald eagle. As consequence, DDT was banned in the United States in 1972 and in most countries thereafter. DDT has seen limited use only as indoor insecticide against mosquitoes in some developing countries.

A key challenge for agricultural chemists working in the field of crop protection has become the continued development of increasingly environmentally friendly pesticides, herbicides, fungicides, and bactericides. Since 1970, the US Environmental Protection Agency (EPA) has closely supervised the use of pesticides. Its authority was strengthened by the Federal Environmental Pesticide Control Act of 1972, amended by the Food Quality Protection Act of 1996. However, human food production has become very dependent on crop protection.

Genetically Modified Food. In the early 1980s, agricultural chemists used genetic engineering to create the first genetically modified plants. The idea was to transfer desired genetic qualities directly. In 1983, the world’s first genetically modified plant was presented by researchers. It was a tobacco plant designed to have a higher resistance to antibiotics. In 1986, in the United States and France, field trials began for genetically modified tobacco plants with increased resistance to herbicides. In 1987, the Belgian company Plant Genetic Systems introduced another genetically modified tobacco plant. This one was more resistant to insects due to the introduction of genes responsible for the production of insecticide toxins in the bacterium Bacillus thuringiensis (Bt). Bt-modification of plant genes has become a key application since.

In the United States, the first commercially sold genetically modified plant was the Flavr Savr tomato of 1994. It was modified to have a longer shelf life after harvesting. However, the high cost of production took this tomato off the market in 1997.

In 1995 and 1996, genetically modified soybeans and canola were introduced in the United States. They were resistant to the widely used herbicides based on the chemical compounds glyphosate and glufosinate. Within two decades genetically modified soybeans accounted for the vast majority of the soybean harvest in the US and globally. The canola harvest was also almost entirely genetically modified in the United States, though less so worldwide. This made these two crops the most widely used genetically altered food of the era.

By the early 2010s, genetically modified food had gone through two generations of applications. Plants of the first generation were modified to be more resistant to insects, having been given the added Bt toxin, or to be more resistant to herbicides used to kill weeds competing with the crops. In addition to soybeans and canola, alfalfa, cotton (for cottonseed oil), and sugar beets were also important crops that were genetically modified in this way. In the second generation, plants were modified to increase their nutritional value and overall quality. Research was also conducted into plants modified to increase their utility as biofuels or to make them grow ingredients for the pharmaceutical industry. Further developments in genetic engineering, such as the CRISPR-Cas9 gene editing method, continued to provide new frontiers in agricultural chemistry.

However, since its beginning, genetically modified food proved highly controversial. Critics have been dubious of its safety, expressed concern about negative environmental and ecological effects, and objected to the plants’ status as commercial, patented food sources. Numerous lawsuits against genetically modified foods emerged, sometimes temporarily banning their use in certain jurisdiction. Test fields for genetically modified plants were sometimes destroyed in acts of ecologically motivated vandalism.

Social Context and Future Prospects

There has been widespread desire to make the applications of agricultural chemistry more and more environmentally friendly. This could be done by increasing the efficiency and accuracy or products such as fertilizers and pesticides. Despite a strong and growing social interest in organic farming, particularly in more developed countries, it became clear that the world’s food needs could not be satisfied without the products of agricultural chemistry.

One of the most controversial applications of agricultural chemistry since the 1990s has been genetically modified food and the development of genetically modified crop seeds. Proponents have embraced the creation of crops that are more resistant to pests or allow the increased deployment of herbicides because the crops themselves are immune to them. The scientific endeavor to increase the nutritional value of food through genetic modification has also been lauded and credited as an advance for humanity. However, there has been very strong opposition to this product of agricultural chemistry. Opponents cite a variety of reasons, including environmental, ecological, and anticapitalist arguments. There is some societal fear of genetically modified foods, even though agriculture has, since its beginning, sought to optimize its crops through human interventions such as selective breeding and hybridization. Overall, genetically modified food is the field of biotechnology in which most future development is expected.

Bibliography

"Agriculture & Food." ACS, www.acs.org/careers/chemical-sciences/fields/agriculture-and-food.html. Accessed 22 Sept. 2023.

Deguine, Jean-Philippe, Pierre Ferron, and Derek Russell. Crop Protection: From Agrochemistry to Agroecology. Enfield: Science, 2009. Print. Proposes a supposedly more environmentally friendly alternative to agricultural chemistry, which the authors term agroecology.

Ferry, Natalie, ed. Environmental Impact of Genetically Modified Foods. Wallingford: CABI, 2009. Print. Comprehensive collection of balanced essays that present and probe varied risks and opportunities of genetically modified food.

Fukuda-Parr, Sakiko, ed. The Gene Revolution: GM Crops and Uneven Development. London: Earthscan, 2007. Print. Overview of how genetically modified foods affect agricultural development in a variety of sampled countries.

Haneklaus, Silvia, ed. Recent Advances in Agricultural Chemistry. Brunswick: Bundesforschungsanstalt fuer Landwirtschaft, 2005. Print. Collection of essays, about half in English, on topics ranging from precision farming to new tools such as yield maps of combinable crops.

Nelson, William M. Sustainable Agricultural Chemistry in the 21st Century. CRC, 2023.

Richmond, Nathan. “Agricultural Biotechnology: Public Acceptance, Regulation and International Consensus.” Chemistry for the Protection of the Environment 4. Ed. Robert Mournighan. New York: Springer, 2005. 111–22. Print. Examines how public opinion in the European Union was shaped on the issue, with the resulting suspicion leading to conflict with the US position and influencing international attitudes toward genetically modified foods.

"Science and History of GMOs and Other Food Modification Processes." US Food and Drug Administration, 19 Apr. 2023, www.fda.gov/food/agricultural-biotechnology/science-and-history-gmos-and-other-food-modification-processes. Accessed 22 Sept. 2023.

About the Author

R. C. Lutz, PhD, is an instructor of business English at an international consulting company. His students include professionals in science and engineering, particularly in the chemical, process, oil and gas, and petrochemical industries. He is the author of survey and encyclopedia articles in the applied sciences, among other subjects. After obtaining his MA and PhD in English literature from the University of California, Santa Barbara, he worked for a few years in academia before moving to a consulting company. He has worked across the globe in the United States, Oman, the United Arab Emirates, Turkey, and Romania.