Feature Story June 2010


Chicken litter being loaded into spreader truck in Northern Louisiana.

Photo courtesy of USDA.


Nurturing Crops, Protecting the Environment
Emphasis on Sound Nutrient Management

By Christa Martin Jones

The emphasis on more and better nutrient management promises advances in farm profitability, conservation technology, and water quality improvements.  Agriculture's ability to marry economy and environment, planning and implementation, and research and technology transfer will define our success.

The United States Department of Agriculture recently accepted proposals for the Mississippi River Basin Initiative grants program, an effort to focus $320 million, over the next four years, for nutrient best management practices in priority watersheds of the Mississippi River Basin.

The International Fertilizer Industry Association, the International Plant Nutrition Institute and The Fertilizer Institute promote the 4 R stewardship concept:  efficient nutrient management depends on applying nutrients from the Right source, at the Right time, in the Right place, and at the Right rate. The concept emphasizes managing all aspects of nutrient application, rather than just one piece. CTIC, Agrium, Agri-Food Canada, and state fertilizer associations also endorse the concept.

Farmers increasingly rely on manure testing and soil testing to influence nutrient application decisions.  Producers can manage drainage water to minimize nutrients lost through tile drains. Equipment manufacturers continue to fine tune variable rate technology. Seed companies are looking at ways to make seed absorb nutrients more efficiently.  New crop simulation models estimate increases over current yield to inform crop and nutrient management decisions.  And more than ever, producers see manure as an asset, a saleable product in many cases.

This emphasis on nutrient management, or nutrient use efficiency, will further drive research into management practices and technologies such as these.  As producers adopt new and better practices, the benefits are two-fold.

First:  Economic Benefits

Cornell Cooperative Extension Educator Joseph R. Lawrence said, “Volatility in the commercial fertilizer markets has led to escalating prices and reduced availability issues that have farmers asking just how many nutrients crops need and the best way to get those nutrients to the crops.”

And if its manure you’re managing, “Be Thankful for Your Manure” author and agronomist Eric Young said, “In these tough economic times, it is good to estimate the value of liquid dairy manure already on the farm and that does not cost anything. Some people are surprised to learn that a 4,500-gallon load of liquid dairy manure is worth about two cents per gallon ($90/load) considering just its N-P-K (nitrogen, phosphorus, potassium) nutrient value.”

David Dunn, University of Missouri Extension.

Photo courtesy of C. Jones.

Regular soil testing can identify nutrient needs to better inform nutrient source, timing, placement, and rate (remember the 4 R’s). Manure testing allows producers to match manure application to crop needs, and avoid spending money for fertilizer that’s not needed.

How important is soil testing?  According to the University of Illinois, the annual investment for nitrogen fertilizers in Illinois exceeds $500 million, attributed to the assumption that fertilizers supply the most nitrogen to the crop. However, research indicates that the soil is often the major source of nitrogen for the crop during the growing season, and that soil type and management history dictates the amount of nutrients in soil.

With nutrient management planning, producers follow steps to the most economical use of nutrients.  Nutrient management plans detail step-by-step how to determine what you have, what you need, how to marry the two, and document your decisions and outcomes.  Each plan is unique to the farm, soils, and landscape.

Mississippi State University Extension likens nutrient management planning to “developing a cash-flow analysis using pounds of N and P instead of dollars.

A new benefit to better nutrient management is on the horizon.  Producers may soon benefit economically from selling the ecosystem services that they provide by installing and maintaining conservation practices, including nutrient management.  Public-private partnerships in many areas of the U.S. have formed work groups to develop water quality trading programs

A World Resources Institute working paper estimates the following in regard to trading potential in the Chesapeake Bay watershed:  Preliminary analyses indicate that the economic benefits of a bay-wide nutrient trading market for nitrogen could be significant for the agricultural, wastewater, and municipal storm water sectors. Depending on credit prices, trading potentially could:

  • Generate new revenue for the agricultural sector and other credit generators at an amount comparable to current levels of annual public funding for agriculture conservation cost-share programs for the bay;
  • Reduce nitrogen removal costs for some in the wastewater sector by as much as 60 percent; and
  • Save the municipal storm water sector hundreds of millions of dollars per year.

Second:  Environmental Benefits

A farmer’s economic decision to limit nutrient application to only what the crop needs can benefit not only the pocket book, but also local and downstream water quality.  If excess nutrients reaching waterways can be avoided, streams, rivers, lakes, groundwater, and reservoirs, and ultimately oceans, reap the benefits.  Efficient nutrient use on the farm bolsters healthy fisheries, tourist economies, wildlife habitat, and drinking water.

Fly fishing in the Gulf of Mexico backwaters.

Photo courtesy of C. Jones.

Proper manure application yields more than one environmental plus. According to Purdue University Extension, proper application of manure will improve soil quality and decrease soil erosion. Manure’s organic carbon provides the energy source for the soil microbes that stabilize nutrient sources and make those nutrients available to crops. And manure applied to the soil surface provides benefits similar to those of crop residue.  Just like crop residue helps protect soil from erosion, studies have shown how manure can coat the soil surface and reduce raindrop impact that can wash soil away.  Less erosion means cleaner water entering adjacent waterways.

If producers can minimize the amount of nutrients leaving the fields, whether the source is manure or commercial fertilizer, benefits include a decreased potential for eutrophication of streams, rivers and lakes.  Eutrophication involves excessive growth of algae and other water-borne plants, above and beyond natural processes, which can greatly degrade fish habitat and the ability of the water body to provide recreational and aesthetic value.

Keeping it Real:  Minnesota’s Nutrient Management Initiative

For the past four growing seasons, Southern Minnesota farmers participated in the Nutrient Management Initiative (NMI) evaluation program funded by Minnesota’s USDA-Natural Resources Conservation Service Environmental Quality Incentives Program (EQIP).  Interested farmers worked with a certified crop adviser to evaluate nutrient comparisons on their own farms.  Farmers compared their own nutrient application rates with either a higher or lower application rate.  Upon completion of the program, the farmer and certified crop adviser received an economic analysis based on the farmer’s actual nutrient costs and yields from replicated strips.  To compensate the farmer’s time and to offset the crop adviser’s fees, the farmer receives $1,200.00.

In 2006, program coordinators launched the NMI as a pilot program.  It has now grown to over 150 on- farm trials in southern Minnesota.  The Minnesota Department of Agriculture assists through program promotion, data collection, data compilation, and educational outreach activities.  Farmers enrolled in the program have experienced a higher yield 74 percent of the time as a result of increased nitrogen application rates, but half of the time did not realize an actual economic advantage due to the additional costs of nitrogen.

Each participating farmer’s certified crop adviser assists with site design, validation of cropping information, and calculating yield results.  Program-eligible fields are preferably high-producing corn-corn or soybean-corn fields, with little variability and no manure or alfalfa history.

The program calls for replication of the farmer’s normal N or P application and another established rate.  Replications occur three times to allow for comparison of crop yield and economic outcomes.  Nitrogen rate sites must maintain a minimum of 30-pound N rate difference.  Nitrogen rate comparisons also require a short check strip with little or no N applied.

Certified crop advisers submit by July 1 cropping information which includes planting date, soil test information, application information, and prices paid for nutrients.  Harvest information must be submitted by December 1.  Farmers and crop consultants receive an evaluation report upon completion based on an annual average corn price and the farmer’s actual nutrient costs.  The farmer’s identity is kept confidential.

Fertilizer application.

Photo courtesy of USDA-NRCS.

Results from each individual site are unique to the participating farmer’s cropping practices, soil characteristics, comparison rates, and local environmental conditions.  Evaluation of overall results (2006-2009) revealed a soybean-corn rotation resulted in a median income advantage of $5.85 per acre accounting for the additional N costs. When comparing this to a corn on corn rotation, the results were not as favorable with a median loss of $-7.60 per acre over the four year period.  Corn following corn sites experienced a 13 percent yield drag compared to a soybean-corn rotation.  Interesting results indicate nitrogen check strips, where little or no N was applied, accounted for 70 percent of the overall yield the majority of time.

Brian Williams works as Water Quality Coordinator for the Pesticide and Fertilizer Management section within the Minnesota Department of Agriculture.  He pointed to survey results that prove farmers and crop consultants value the NMI program as a useful tool for evaluating nutrient management decisions.

Williams commented, “Farmer and crop consultants indicated they increased their knowledge of application rates and timing, nutrient loss potential and impacts on the environment, a better understanding of nutrient contributions, and economic outcomes as a result of their management decisions.”

Planning Can Improve Yields and Optimize Inputs

Mississippi State Extension offers this definition of nutrient management:  “managing crop fertility inputs and other production practices for efficient crop growth and water quality protection.” Its web site promotes the development and use of nutrient management plans to address site-specific conditions, while maintaining profitability and maximizing environmental benefits. The plan can address manure and/or fertilizer management as well as any other source of crop nutrients. 

Nutrient management planning involves obtaining soils information, estimating yield potential, determining nutrients needed to reach that potential, calculating available nutrients in manure (if applicable), and estimating residual nutrients.  Other considerations include the potential for nutrients to run-off or leach, proper application of manures or fertilizers, and how records will be kept.

The USDA Natural Resources Conservation Service or local conservation district can assist producers with nutrient management planning and implementation, and often the producer can take advantage of cost-share programs to offset expenses.  Help may also be available from private sources, such as certified crop advisers. The producer develops the plan with the assistance of a consultant, and learns how and why the plan can be advantageous.

The nutrient management plan remains flexible to accommodate for changes in weather, markets, and soil conditions.  Refinement of the plan occurs after each season as well as over the long term, as the producer gains intimate knowledge of crop nutrient needs.

Learning to Share

Possibly the most advanced innovations in nutrient management technology will be born of our ability to learn from each other.  As agriculture produces more, it must conserve and even improve the quality of natural resources.  Efficient nutrient management will comprise cornerstone methods for sustaining the health of our waters, and public and private research and demonstration facilities seem poised to deliver new solutions.


Enhanced data sharing among state and federal agencies, universities, and countries will improve the overall quality of data and collection tools, substantiate findings, and provide decision makers with a larger pool of information.  Electronic networks that allow researchers and practitioners to share information will likely be important to reaching both yield and resource conservation potential. 

Better information sharing will speed on-farm realization of nutrient management innovations.  Nutrient management planning provides the key to effective on-farm application of new technologies, products, and methods.  And both producers and the public stand to benefit, economically and environmentally, from improved nutrient use efficiency.


CTIC’s Livestock Waste Management web site

Illinois Soil Nutrient Management Test

Minnesota Department of Agriculture’s Nutrient Management Initiative
www.mda.state.mn.us/nmi or contact Brian Williams at brian.c.williams@state.mn.us