Agrochemical

Agrochemicals are chemical products used in conventional or industrial agriculture. The term is a contraction of "agricultural chemical." While people sometimes use the word to mean only pesticides, it actually covers a wide range of substances. These include synthetic fertilizers, which provide nutrients to soil. They also include pesticides, which manage pests. Other types include plant hormones and plant growth regulators, known as PGRs. These chemicals can influence how a plant grows. There are also insect attractants, insect repellents, and plant defense inducers. Some agrochemicals act as herbicide safeners or soil conditioners. Even livestock receive agrochemicals, such as animal growth regulators and antiparasitics.

Farmers apply these substances using several different technical methods. One common method is foliar spray, where liquid is sprayed onto the leaves. Another method is root drenching, which involves applying liquid directly to the roots. Some farmers use the broadcasting of granules to spread solids across a field. Seed coating is another technique where chemicals are applied to seeds before planting. Each method ensures the chemical reaches the intended part of the plant or soil. These processes are central to modern industrial farming systems.

Agrochemicals are categorized by how they are manufactured. Nitrogen fertilizers are created from ammonia (NH3). This is produced through a specific method called the Haber–Bosch process. Phosphate fertilizers are produced using various minerals. Most pesticides are made indirectly from petrochemicals, which are chemicals derived from petroleum. However, some pesticides are produced biologically from living organisms. This distinction in manufacturing defines the different chemical groups used in the field. These processes require complex industrial facilities to function.

Humanity has used various substances to aid agriculture for thousands of years. In ancient Sumeria and China, people used inorganic pesticides. Historically, farmers relied on compost and manure to fertilize their crops. The manufacture of inorganic fertilizers began in the early 20th century. Production saw a massive increase during the second half of the 20th century. Many modern pesticides were developed in the late 20th century. Their use expanded greatly during a period known as the Green Revolution. This era changed how much food the world could produce.

The global market for these chemicals involves massive quantities and high values. In 2018, world pesticide sales were estimated at $65 billion. About 88% of those sales were for agricultural use. In that same year, 120 million metric tons of nitrogen fertilizer were used. The world also used 44 million metric tons of phosphorus and 45 million metric tons of potassium. Global sales for inorganic fertilizers in 2018 reached about $151 billion. China, the United States, India, and Russia dominate nitrogen and phosphorus production. Canada is the largest producer of potassium.

Using agrochemicals involves significant ecological and health considerations. Improper use or release can lead to environmental pollution. Chemicals can cause damage to waterways through a process called runoff. Accidental spills can also occur, especially during extreme weather events. The book "Silent Spring" by Rachel Carson brought global attention to these ecological impacts. This includes concerns about biodiversity loss and ecosystem health. Because of these risks, many countries have highly regulated systems. Farmers may need government-issued permits to purchase or use certain approved chemicals.

To manage these risks, many farming systems use alternatives to traditional agrochemicals. Sustainable agriculture and organic farming are two such systems. Other methods include biodynamic farming and agroecology. Some farmers use vertical farming or hydroponics to grow food. Techniques like crop rotation, composting, and intercropping help manage soil health. Precision agriculture uses technology to apply chemicals more accurately. There is also biological pest control and integrated pest management. These diverse methods aim to reduce the reliance on heavy chemical use.