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Publication #HS1264

What is 4R nutrient stewardship?1

Guodong Liu, Kelly Morgan, Yuncong Li, Lincoln Zotarelli, James DeValerio, and Qingren Wang2

Introduction

This EDIS publication is the first in a series on understanding the four RIGHT (4R) nutrient stewardship applications for crop production. There is a fact sheet, SL411, introducing the details of the 4Rs (http://edis.ifas.ufl.edu/ss624). This fact sheet focuses on the scientific principles, the importance, and assessement of the 4Rs. It also emphasizes the relationship among the 4Rs and who decides what is correct in the 4Rs.

Fertilizers play an essential role in Florida’s commercial crop production and in food security nationally and worldwide. Fertilizers provide nutrients essential for crop production but also pose pollution risks to the environment, which can constrain both the economy and society. To control water pollution caused by fertilizers, best management practices (BMPs) were first defined by the U.S. Environmental Protection Agency (EPA) in the federal wastewater permit regulation in 1977. BMPs are defined as “schedules of activities, prohibitions of practices, maintenance procedures, and other management practices to prevent or reduce the pollution of waters of the United States” that “also include treatment requirements, operating procedures, and practices to control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.” (EPA 2015b) To ensure the environmental, social, and economical sustainability of commercial crop production, an overview of a new and innovative approach to BMPs for fertilizer application known as 4R nutrient stewardship is available to environmentalists, Extension agents, crop consultants and advisors, growers, and graduate students who are interested in agriculture.

What does 4R nutrient stewardship mean?

For any commercial crop production, the quality of nutrient management practices is determined by the 4Rs. The 4R nutrient stewardship concept is defined as

  • the RIGHT fertilizer source is applied at

  • the RIGHT rate at

  • the RIGHT time, and in

  • the RIGHT place for a particular crop.

Figure 1. 

Schematic diagram of the 4Rs.


Credit:

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This simple management concept can help growers implement appropriate management practices for fertilizer application to enhance the sustainability of agriculture. All of those involved in crop production, including growers, crop consultants and advisors, extension faculty, research scientists, policymakers, consumers, and the public, must participate in advancing the goals of the 4R program.

Why is 4R nutrient stewardship so important?

4R nutrient stewardship is important because there are many sustainability issues related to fertilizer and nutrient management in commercial crop production such as

  • food security and safety,

  • soil fertility and quality,

  • non-renewable resources,

  • eutrophication (nitrate, phosphate, algae bloom pollution) and water quality,

  • air quality (ammonia volatilization),

  • greenhouse gas emission (nitrous oxide (N2O)),

  • stratospheric ozone depletion caused by N2O, and

  • heavy metal pollution in soil (cadmium).

Each of the items on the above list is closely associated with human wellness and quality of life.

Are the 4Rs interdependent or independent?

The four facets of nutrient management practices are fully interdependent and linked in the cropping system.

  • The 4Rs of nutrient management—source, rate, time, and placement—are fully linked and interconnected to every step of management practices for every farming system.

  • No one of the 4Rs can be right when any of the 4Rs is wrong.

  • The 4Rs must work in sync with each other and with the environment.

  • The combination of the 4Rs changes with the farming system.

  • The combination of the 4Rs changes with local water quality issues.

What are the scientific principles for 4R nutrient stewardship?

The fundamental scientific principles are the basis of 4R nutrient stewardship because the basic sciences are fundamental to the growth and development of plants grown on soils.

  • The sciences applied to the 4Rs include biology, chemistry, physics, etc.

  • Applying scientific principles to managing plant nutrients tests the scientific principles of plant nutrition.

  • Scientific principles help guide the development of practices that determine the 4Rs.

  • The principles are the same worldwide, but actual practices are crop and site-specific.

How should we assess implementing 4R nutrient stewardship?

The goals of 4R nutrient stewardship are to enhance the economic, environmental, and social sustainability of the cropping system. All of the indicators related to the economy, environment, and society should be assessed (Table 1).

Table 1. 

Crop yield

Yield stability

Product quality

Nutrient use efficiency of all applied fertilizers

Water use efficiency

Energy use efficiency

Labor use efficiency

Profitability

Soil productivity

Soil quality

Water quality

Air quality

Biodiversity

Farm income

Nutrient budget

Who decides what is right in the 4Rs?

All participants decide the 4Rs. Participants include

  • Growers.

  • Scientists.

  • Extension faculty.

  • Crop consultants and advisors.

  • Environmentalists.

  • Agribusiness professionals.

  • Stakeholders.

Everything from crop selection to market choice and consumption are factors that will determine what set of nutrient management practices are correct.

Summary

  • 4R nutrient stewardship includes the right fertilizer source applied at the right rate, the right time, and the right place for a particular crop producing sustainable economic, social, and environmental outcomes.

  • The 4Rs are all interdependent and interconnected.

  • The 4Rs play irreplaceable roles in sustainability of the economy, society, and environment.

  • 4R nutrient stewardship is guided by biology, chemistry, and physics.

  • 4R nutrient stewardship is an essential tool for commercial crop production BMPs.

  • The performance measures and indicators include use efficiencies of fertilizers, water, energy, and labor, crop yield and yield stability, soil productivity, profitability, etc.

  • All stakeholders of commercial crop production decide what counts as “right” in the 4Rs.

References and Further Reading

Bruulsema, T., J. Lemunyon, and B. Herz. 2009. “Know your fertilizer rights.” Crops & Soils March–April 2009: 13-18. http://www.ipni.net/ipniweb/portal/4r.nsf/0/1748D80FEC9FE7C185257DF10074A028/$FILE/Know%20Your%20Fertilizer%20Rights.pdf. Accessed July 2, 2015.

Federal Water Pollution Control Act (Clean Water Act). 2002. 33 U. S. C. § 1251 et seq. Accessed July 6, 2015. http://www.epw.senate.gov/water.pdf

Hochmuth, G., R. Mylavarapu, and E. Hanlon. 2014. The Four Rs of Fertilizer Management. SL411. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/ss624. Accessed July 2, 2015.

Mikkelsen, R. L. 2011. “The ‘4R’ Nutrient Stewardship Framework for Horticulture.” HortTechnology 21(6): 658–662.

U.S. Environmental Protection Agency (EPA). 2015a. “Summary of the Clean Water Act.” Accessed July 6, 2015. http://www2.epa.gov/laws-regulations/summary-clean-water-act

EPA. 2015b. “Title 40, Subpart 122.2: Definitions” in Electronic Code of Federal Regulations. Washington, DC: U.S. Government Publishing Office. Accessed July 2, 2015. http://www.ecfr.gov/cgi-bin/text-idx?SID=9be8514046d3f051480db50d6c4f7548&mc=true&node=pt40.22.122&rgn=div5#se40.22.122_12.

Footnotes

1.

This document is HS1269, one of a series of the Horticultural Sciences Department, UF/IFAS Extension. Original publication date July 2015. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Guodong Liu, assistant professor, Horticultural Sciences Department; Kelly Morgan, associate professor, Soil and Water Science Department, Southwest Florida Research and Education Center; Yuncong Li, professor, Tropical REC; Lincoln Zotarelli, assistant professor, Horticultural Sciences Department; James DeValerio, Extension agent II, UF/IFAS Extension Bradford County; and Qingren Wang, Extension agent II, UF/IFAS Extension Miami-Dade County; UF/IFAS Extension, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.