Food security

What fertilizers and pesticides commonly go on ag fields and why?

At least three times a day, most humans and many animals consume food produced by the agricultural sector. Our cotton and natural fiber clothing is almost all made through agriculture. Our fuels are enhanced by biofuels. All of these agronomic crops require what agronomists call “inputs”: seeds, water, nutrients and any pesticides necessary to protect yields. Each input has specific benefits and cautions associated with their use in crop production.

Cotton bolls on stems
Even fiber crops, like cotton, need nutrient and pest management, Credit: SV Fisk

Nutrients include elements like nitrogen, phosphorus, and potassium. They are crucial for plant growth, development, function, and reproduction. The amount of these elements available in the soil also affects the quality of crops. Nitrogen is a major component of plant chlorophyll, amino acids, protein, and plant DNA. Phosphorus is a vital nutrient for photosynthesis, respiration, energy storage and transfer, cell division, cell enlargement, and other processes in plants. Potassium is essential for nearly all plant processes needed to sustain growth, reproduction, plant protection, and crop quality. Just like you might need to take vitamin supplements if you have nutritional deficiencies, our crops sometimes need fertilizers. Fertilizers are used to supplement these essential plant nutrients to promote optimal production.

Pesticides protect plants from weeds, insect damage, and diseases. (To read more about pesticides visit here.) The most common herbicides are glyphosate, atrazine and “2,4-D”. Herbicides control grass and broadleaf weeds that steal sunlight, water and nutrients from our desired crops.

Just like your doctor might prescribe medicine doses based on your weight, age and gender, farmers also look at many factors when determining their use of fertilizers and pesticides. Applying these inputs correctly is critical for the success of the crop producer and the health of the consumer and the environment. And, just like recommendations for prescription use have changed over the past few decades, best management of fertilizer and pesticides has changed, too. Research has been conducted on these common inputs and has led to improvements in management practices.

Most fertilizer recommendations for crop producers focus on 4R’s: applying the Right source of fertilizer at the Right rate in the Right place and at the Right time. Research is ongoing about which fertilizers work best for various crops. In addition, not all fertilizers work in the same way. Farmers want to apply fertilizers at the right dose. Adding too little means wasted employee time, and a lower yield. Applying too much wastes money – and is bad for the environment. And, when to fertilize is a big area of research. Some fertilizers are best applied early in the growing season, while others are best applied just as flowers begin blooming on the plants.

At the time when commercial fertilizers were made available, yields were low, and farming was tedious work. The world’s population was rising quickly. Using fertilizer enabled growers around the world to help combat starvation and malnutrition. Pesticides were developed in response to large outbreaks of disease, like wheat rust. Besides breeding new crops that are rust-resistant, farmers use pesticides to help combat outbreaks.

Farmer and agronomist talking
Agronomists and growers can review information from precision ag technology to determine the best course of action for individual fields. Credit: Jerome Beck

And, farming practices change. Why? Because farming is the practice of scientific principles – and scientific findings are always changing. As an example, let’s use antibiotics. When they were first discovered, they were prescribed widely – and saved many lives in the process. However, over time, health care practitioners began to note the arrival of antibiotic resistant bacterial infections. And, with this, came many changes in the way antibiotics are prescribed. Medicine is a science, and science is always looking for the next best outcome.

A newer area of fertilizer and pesticide research is called precision agronomy. Using agricultural drones, soil and crop sensors and computer technology, agronomists can make fertilizer and pesticide recommendations that are specific to each farm field and even to specific areas within fields. For example, farmers can now use a crop sensor to determine and adjust real-time nitrogen fertilizer rates as the tractor moves through the field, or they can use other sensors to detect and apply pesticide only to areas with weeds. Click here to read more about a precision agronomist and watch a video in action.

The ultimate goal with fertilizer and pesticide use is to produce the best crop possible while minimizing environmental harm. Research and advancements in technology are making these goals a reality. Nearly all inputs can now be more precisely applied than ever before, and input prescriptions are improving as our ability to quantify, understand, and estimate field variation improves. This capacity will continue to improve in the future. Producers may have the capability to manage individual plants across large agricultural fields in a real-time, automated fashion. These advancements will help ensure proper stewardship of agriculture inputs that help feed, clothe, and fuel a rapidly growing human population.

Answered by Matt Yost, Utah State University

About us: This blog is sponsored and written by members of the American Society of Agronomy and Crop Science Society of America. Our members are researchers and trained, certified, professionals in the areas of growing our world’s food supply while protecting our environment. We work at universities, government research facilities, and private businesses across the United States and the world.

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