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Agronomy and crop science are the parts of agricultural science concerned with how field crops are grown, improved, and managed in soil and climate conditions that cannot be fully controlled. If you arrived here wanting the whole map of agricultural research, including animals, horticulture, food systems and rural economics, start with What Is Agricultural Science?; this page goes one level down and explains the crop-and-soil core of that map: what agronomists and crop scientists study, how they test ideas in the field, who organizes and funds the work, and where research administrators meet it.
What Is Agronomy?
Agronomy is the science and practice of producing field crops — grains, oilseeds, forages, fiber and similar broadacre crops — while managing the soil, water, nutrients and pests that determine how those crops perform. It is an applied, systems-oriented discipline: an agronomist rarely studies one variable in isolation, because yield in a real field is the joint outcome of genetics, weather, soil, management timing and pest pressure. The word is used for both the research field and the professional practice of advising growers, and the two overlap heavily in land-grant university departments, where research, teaching and Extension are organized together.
The American Society of Agronomy describes itself as the professional home for scientists, educators and practitioners working in agronomic sciences, and states that it was established in 1907. That framing — scientists, educators and practitioners under one roof — is a fair summary of how the discipline works.
Agronomy vs. Crop Science vs. Agricultural Science
These three terms are nested, and they are often used loosely, so it helps to separate them.
- Agricultural science is the broad umbrella. It covers crop and soil work but also animal science, horticulture, agricultural and biosystems engineering, food science, entomology, plant pathology and agricultural economics. See the agricultural science guide for that wider landscape and for how it differs from neighbouring fields.
- Agronomy sits inside that umbrella and focuses on the crop-in-the-field system: crop physiology and production, cropping systems, soil fertility and management, water and nutrient use, and the decision-making that connects them.
- Crop science is most often used for the crop-improvement and crop-biology side: how plants grow and respond to their environment, and how to develop better varieties. In practice the line between agronomy and crop science is blurry, and in North America the major professional societies treat them as sister fields (see the societies section below).
A useful rule of thumb: agricultural science asks how food and fiber systems work, agronomy asks how to manage a crop and its soil to perform in a given environment, and crop science asks how to understand and improve the crop itself. Because soil is half of the agronomic system, agronomy also shares ground with soil science, and because crop health depends on disease, it shares ground with plant pathology. Underneath all of it is basic plant biology, covered in What Is Botany?
Major Subfields
Cropping systems and crop production
This is the heart of agronomy: how a crop is established, fed, protected and harvested, and how crops are arranged in space and time. Typical research topics include planting date and density, crop rotation, intercropping, cover crops, tillage and residue management, and the way these choices interact. Cropping-systems research is usually long-term and multi-site, because the effects of rotation or soil management build up over years and differ by location.
Soil fertility and nutrient management
Agronomists study how much of each nutrient a crop needs, how much the soil can supply, and how fertilizer and organic amendments change the balance — including the environmental side of the question, such as nutrient loss to water. Much of this work is done in partnership with soil scientists; the dedicated treatment is in the soil science guide.
Plant breeding and genetics
Plant breeding develops improved crop varieties by combining genetic variation, selecting superior plants, and testing the results across many environments. Methods range from conventional crossing and selection to marker-assisted selection, genomic prediction and genetic engineering or genome editing. Breeding is where crop science meets genetics, and it is also where agronomy’s field-trial discipline matters most: a variety only counts as improved if it performs better across the environments where it will actually be grown. New varieties also raise intellectual-property questions; in the United States, one framework for protecting certain plant varieties is described in the dictionary entry on the Plant Variety Protection Act.
Crop physiology and stress biology
Crop physiologists study how plants capture light, use water and nutrients, set yield, and respond to heat, drought, flooding, salinity and nutrient limitation. Their results feed both breeding targets (which traits to select for) and management advice (how to time inputs).
Weed, pest and disease management in crops
Weed science, and the integration of insect and disease control into crop management, are core agronomic concerns. Disease biology has its own discipline — see What Is Plant Pathology? — but the management question of how to keep a crop healthy at acceptable cost sits in agronomy.
Precision agriculture and crop modeling
Precision agriculture uses location-aware tools — satellite positioning, yield monitors, sensors, variable-rate equipment and imagery — to manage variation within a field instead of treating the whole field as uniform. It depends heavily on remote sensing and on data analysis. Crop simulation models, which predict growth and yield from weather, soil and management inputs, play a parallel role: they help extend results from a few trial sites to many environments and test management scenarios before anyone plants a plot.
How Agronomic Research Is Done
Field trials are the signature method
Controlled laboratories and growth chambers are useful, but the defining agronomic claim — this practice or variety works in real fields — has to be tested in real fields. Field trials face a problem that bench experiments largely avoid: the soil is not uniform. Fertility, moisture, drainage and pest pressure vary across even a small field, and that background variation can easily be mistaken for a treatment effect. Field-trial design exists to prevent that mistake.
The three design principles
- Replication. Each treatment is applied to several independent plots, not one. Replication lets you estimate how much plots treated alike differ by chance, which is the yardstick for deciding whether a difference between treatments is real. Repeating a measurement within a single plot, or sampling the same plot many times, is not replication — treating it as such is the error described in this guide to pseudoreplication and the experimental unit, which is written for animal studies but applies the same logic to plots.
- Randomization. Treatments are assigned to plots by chance rather than by judgement or convenience, so that no treatment systematically gets the better corner of the field and so that standard statistical tests are valid.
- Blocking (local control). The field is divided into blocks of similar plots, and every treatment appears in every block, so that known sources of variation such as a slope or a soil boundary are separated from the treatment comparison. The idea is developed in Blocking in Experimental Design.
Common field designs
The most common layout is the randomized complete block design. Beyond it, agronomists use Latin square designs when variation runs in two directions, and split-plot designs when one factor (for example tillage, which needs large equipment and large plots) is hard to change and another (for example variety or fertilizer rate) can be applied to small subplots. Factorial arrangements test several factors and their interactions at once. The general framework is in the dictionary entry on experimental design, and the usual analysis tool for these designs is analysis of variance (ANOVA), extended to mixed models when blocks and sites are treated as random effects.
Multi-environment and long-term trials
A result from one site and one season is weak evidence, because weather differs year to year and soils differ place to place. Agronomy therefore relies on trials repeated across locations and years, and on statistical methods that separate genotype, environment and their interaction. Long-term experiments, which keep the same treatments on the same plots for many years, are valuable for slow processes such as soil carbon change, and are a distinctive feature of the field.
On-farm research
Alongside station-based plots, researchers increasingly run trials on working farms, often with the grower’s own equipment. These trials trade some experimental control for realism and for grower involvement, and they depend on the same replication and randomization rules to be interpretable.
Other tools
Field work is supported by greenhouse and growth-chamber studies, soil and plant tissue analysis, remote sensing, genotyping and phenotyping platforms, and statistical and simulation software. Agronomy is also a data-heavy field, so plot-level data, metadata and analysis code are subject to the same research data management expectations as any other discipline.
Regulatory Touchpoints for Biotechnology Field Trials
Most agronomic field trials involve conventionally bred material and need no special federal permission beyond ordinary land, safety and agreement requirements. Trials of certain organisms developed using genetic engineering are different. The USDA Animal and Plant Health Inspection Service (APHIS) states on its Biotechnology Regulatory Services page that it regulates the importation, interstate movement, or environmental release of certain organisms developed using genetic engineering that may pose a plant pest risk, and that it implements its biotechnology regulations at 7 CFR part 340 under the authority of the Plant Protection Act. Developers can pursue either permits or notifications, depending on the situation.
The details here have been in flux. APHIS’s own page flags a court vacatur of its 2020 biotechnology regulations as a trending topic, so the practical requirements for a given trial should be confirmed directly with APHIS Biotechnology Regulatory Services, not inferred from older summaries. Separately, institutions typically route work with recombinant or synthetic nucleic acids through their Institutional Biosafety Committee and their research compliance office. Which regulator, permit or notification applies is a question for the compliance office and APHIS, not for this overview.
Societies, Journals, and Meetings
Three sister organizations anchor the North American community. The American Society of Agronomy (ASA) is the oldest of them, established in 1907 according to its own site, with more than 6,000 members and more than 12,000 Certified Crop Advisers; it is organized into seven sections covering agronomic production, biometry and statistical computing, climatology and modeling, education and extension, environmental quality, global agronomy, and land management and conservation. The Crop Science Society of America (CSSA) and the Soil Science Society of America (SSSA) are its sister societies. Together the three publish thirteen peer-reviewed journals, six of them gold open access, spanning agronomy, crop, soil and environmental science, and they hold a joint annual meeting that the ASA site calls CANVAS.
The Certified Crop Adviser credential noted above is a reminder that agronomy has a large professional-practice side. Researchers in the field often publish in the society journals, present at the joint meeting, and work alongside advisers and Extension specialists who carry results to growers. Because societies, journals and meeting names change over time, confirm current details on each society’s website before citing them.
How Agronomic Research Is Funded
In the United States, the dominant public funder of extramural agricultural research is the USDA National Institute of Food and Agriculture (NIFA). Its flagship competitive program is the Agriculture and Food Research Initiative (AFRI), which NIFA describes as the nation’s leading competitive grants program for agricultural sciences. Congress established it in the 2008 Farm Bill and reauthorized it in 2018. NIFA awards AFRI grants across six Farm Bill priority areas, the first of which, Plant Health and Production and Plant Products, is the natural home for much crop research; others such as Agriculture Systems and Technology and Bioenergy, Natural Resources, and Environment also reach agronomic topics. NIFA states that the portfolio supports research, education and Extension, and lists biotechnology and conventional breeding among the activities funded. Eligible applicants include state agricultural experiment stations, colleges and universities, and other organizations. Program areas, deadlines and funding levels change by cycle, so use the current program announcement; our guide to NIFA AFRI program areas and submission covers the application mechanics, and the funding section of the agricultural science guide places AFRI alongside the other agricultural funders.
Crop research is also funded by the USDA’s own intramural research agency, by the National Science Foundation for fundamental plant biology, by state agencies and commodity groups, and by private companies. Industry funding is especially common in variety testing and breeding, and it brings its own agreement, data-rights and conflict-of-interest questions.
Training and Careers
Agronomy and crop science are typically studied through departments of agronomy, crop and soil sciences, plant sciences or similar names, most often at land-grant universities. Graduate training emphasizes experimental design and statistics heavily, because field data are noisy. Careers span university and government research, seed and agricultural-input companies, crop consulting and Extension, and policy or regulatory work.
Where Research Administration Meets Agronomy
Agronomic research has some distinctive administrative features worth knowing:
- Land and field sites. Trials run on university farms, off-station sites and grower fields. Access, liability and site-use terms need to be settled before planting, and a field season cannot be restarted when a late agreement is signed.
- Seasonality. Planting and harvest windows drive budgets, no-cost extensions and subaward timing. A delay of a few weeks can cost a whole year of data.
- Multi-year, multi-site awards. Long-term and multi-location experiments lean on subawards and multi-institution agreements.
- Genetic resources and varieties. Germplasm exchange, material transfer terms and variety protection add intellectual-property and compliance steps.
- Biotechnology compliance. As described above, certain genetically engineered material triggers regulatory and biosafety review before any release.
- Data. Trial data, metadata and code should be managed so that a result from one site and season can be reused and combined later.
For the study-design side of this work, the CASRAI research methods hub collects related guides.
Frequently Asked Questions
Is agronomy the same as agricultural science?
No. Agricultural science is the broad umbrella covering crops, animals, food systems, engineering and economics. Agronomy is one major part of it, focused on crop production and soil management. See What Is Agricultural Science? for the full picture.
What is the difference between agronomy and crop science?
Usage overlaps. Agronomy usually emphasizes managing crops and soils in production systems, while crop science usually emphasizes crop biology and improvement, including breeding. Many university departments and societies combine them.
What is the difference between agronomy and horticulture?
Agronomy is generally associated with field crops grown at large scale, such as grains, oilseeds and forages, whereas horticulture covers fruits, vegetables and ornamental plants. Both are parts of plant-based agricultural science.
Is plant breeding part of agronomy?
Plant breeding is usually grouped with crop science and genetics, but it is closely tied to agronomy because new varieties must be tested in field trials and recommended with management practices suited to them.
Why do field trials need replication and randomization?
Because fields are not uniform. Replication provides an estimate of chance variation, randomization prevents systematic bias in where treatments land, and blocking removes known sources of variation from the comparison. Without them, a difference between plots may simply reflect where the plots were.
Do all field trials need APHIS permission?
No. APHIS regulates the importation, interstate movement or environmental release of certain organisms developed using genetic engineering that may pose a plant pest risk. Whether a particular trial falls under that oversight should be confirmed with APHIS and your institution’s compliance office.
Who funds agronomy research in the United States?
The largest public competitive source is USDA NIFA’s Agriculture and Food Research Initiative, supplemented by USDA intramural research, NSF for fundamental plant science, state and commodity-group funding, and private industry.
