The Effectiveness Of Nutrient Management Plans

UPDATED: January 28, 2013

Nutrient management plans (NMPs) are implemented to supply plants with ideal amounts of nutrients, minimize runoff pollutants, and maintain or improve the soil condition. As we continue to understand the effects farming practices have on the environment, NMPs present farmers with a set of conservation practices designed to reduce harmful pollutants while obtaining optimal crop yields.

Many U.S. Animal Feeding Operations (AFOs) produce excess N and P compared with the nutrient requirements of their cropland, and more regulations are being implemented to help reduce the pollution. In 1998, in response to President Clinton’s Clean Water Action Plan, the USDA and USEPA developed a Unified National Strategy to minimize the effects of AFOs on water quality and public health.

Today, each state has a different set of guidelines for NMPs, most of which involve farmers developing field-by-field records of nutrient applications. Currently, only Delaware and Maryland have nutrient management laws requiring all farmers to implement NMPs.

A study published in the March–April 2012 Agronomy Journal evaluates how effectively four dairy farms implemented their own NMPs from 1999 to 2005. The researchers, from the University of Connecticut and the USDA, compared the farmers’ reported practices with the recommended manure and fertilizer management plans and evaluated whether manure and fertilizer management had significant effects on the nutrient status of soil and corn tissue tests.

The majority of the cropland of the four farms selected for this study was used for corn silage, with substantial acreage also used for grass hay. The farmers’ priority for management and nutrient tests was corn, so only corn fields were used in this study. Each of the soils at the four farms had sandy loam to loam texture, a slope of 0% to 8%, organic matter content of 3 to 6%, and were moderately well to well-drained.

The NMPs of each farm consisted of two parts: a baseline year and the implementation years. In the baseline year, the research team collected information about each farm’s nutrient management. The factors considered included the number of livestock, cropland acreage, nutrient status of the cropland, manure production, manure management, and fertilizer management.

The farmers kept field-by-field records about manure and fertilizer applications but made no changes to the management of their nutrients. The information collected in the baseline year was used to develop field-by-field recommendations for manure and fertilizer management to be applied in the subsequent implementation years. The recommendations were based primarily on soil tests.

The rate of manure recommended was based on the amount of P needed by the crop, which researchers estimated from soil test results. If the farm had excess manure after fulfilling the crop’s P needs, recommendations were made to apply manure at a rate equal to the amount of P expected to be removed by the crop. If the farm still had manure leftover, it was to be applied to fields to meet the N requirement for the crop to fields that had a low potential to export P to water bodies. Chemical fertilizer recommendations were made after all manure was allocated.

Soil samples were routinely collected by farmers or crop advisers and analyzed at the University of Connecticut Soil Testing Laboratory. Samples were taken from the surface 30-cm layer from most of the fields in late spring when the corn was 15 to 30 cm tall. The samples underwent pre-sidedress nitrogen tests (PSNTs), which indicate how much nitrogen is available in the soil.

Cornstalk samples were also collected for corn stalk nitrate tests (CSNTs), which provide a retrospective assessment of a season’s nitrogen management. Farmers collected 15 cornstalk samples from each field during the period ranging from one week prior to harvest through one day after harvest.

During the implementation years, farmers were provided the results of the PSNT test and the recommended N sidedress. However, the percentage of times the farmers that actually applied the recommended N rate when the sidedress N recommendation was greater than zero was low, ranging from 6% to 24%.

The percentage of times the farmers applied the recommended N rate ranged from 79% to 90% when the recommended rate was zero. This data implies that farmers were not likely to follow recommendations derived from PSNT tests when the recommendation was to apply N. This behavior is supported by scientific reports showing that PSNT tests are most reliable when the N recommendation is zero.

The farmers applied fertilizer P at the recommended rate in the NMPs in the majority of the fields. In most years, more than 50% of the fields received a recommendation of zero fertilizer P, and farmers tended to follow that recommendation. Across the four farms, the overapplication of P occurred in less than 3% of the field-by-year combinations. This data shows that farmers were willing to adopt P fertilizer recommendations provided in their NMPs.

Only a small percentage of the fields, ranging from 3% to 37%, received the recommended amount of manure N and P. Variability in the amount of residual N available from previous manure applications caused great variance in the PSNT and CSNT tests, indicating that several years of data are needed before these tests can be used to accurately evaluate the performance of a NMP.

The four farmers in this study seemed confident that fertilizer recommendations were appropriate when based on soil tests, especially recommendations for fertilizer P. However, there was no significant change in soil test P values, probably due to the large spatial variation of P in the fields.

The results from this study showed no decreasing trend in the concentrations of nitrate in the PSNT and CSNT tests. The large variation in the amounts of manure and fertilizer applied by the farmers may be responsible for this lack of improvement.

Only a small percentage of fields received the recommended amount of manure application, and no significant decrease in the amount of manure over application compared with the recommended amount was found in this study.

Documenting improvements in N and P management after the implementation of an NMP proved to be a difficult task for the researchers of this study, due to both biological and management factors, such as non-uniform manure spreading and annual variations in weather, especially rainfall.  

Overall, the researchers say that manure and fertilizer management on dairy farms could be improved by using a longer timeframe than the three- to five-year plans typically used by NMPs. Management plans implemented using a process of adaptive management for N, which provides more detailed, continuous evaluations about the N status of corn fields, have also been shown to improve N management.

Leave a Reply

Crop Inputs Stories
Crop InputsPlatform Specialty Products To Acquire Arysta LifeScience
October 20, 2014
Once the acquisition is complete, Platform Specialty Products will combine Arysta LifeScience with previously acquired companies Agriphar and Chemtura Crop Solutions. Read More
MicronutrientsMicronutrients Going Macro
September 9, 2014
Between 2014’s fantastic growing conditions and a heightened awareness on plant nutrition, the major players in micronutrients are gearing up for another big year. Read More
FertilizerFall Fertility 2014: Forecasting Fertilizer Use
September 7, 2014
Great crops this year have tapped the soil, and fall work is definitely called for, but how challenging will that get? Read More
FungicidesSudden Death Syndrome, Brown Stem Rot Reported In Indiana Soybeans
September 3, 2014
Farmers and retailers should be watching for symptoms of these two diseases over the next few weeks as they are best managed through preventative methods. Read More
Top 100 Articles
CropLife 100Pinnacle Agriculture Acquires Minnesota Retailer
April 14, 2015
Pinnacle Agriculture Holdings, LLC, ranked No. 6 on the CropLife 100,  has successfully acquired Liebl Ag, LLC in Ada, MN.  Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Grain Shuttle Loading Facility
April 13, 2015
CHS Inc., the nation’s leading cooperative and ranked No. 5 on the CropLife 100, and Aurora Cooperative (ranked No. 21) Read More
CropLife 100GROWMARK Acquires Missouri Refined Fuels Terminal
April 2, 2015
Bloomington, IL-based GROWMARK and Magellan Pipeline Co. have entered into an agreement in which GROWMARK will acquire the refined fuels Read More
CropLife 100Wilbur-Ellis Acquires South Dakota Retailer
April 2, 2015
Wilbur-Ellis Co.’s Agribusiness Division, a recognized leader in precision agriculture technology and the distribution and marketing of plant protection, seed Read More
CropLife 100The McGregor Co. Closes Smith-Kem Acquisition
April 2, 2015
The McGregor Co. — ranked No. 16 on the CropLife 100 list of largest U.S. ag retailers — has completed Read More
CropLife 100BRANDT Commemorates National Ag Day
March 20, 2015
The Illinois agriculture community gathered at BRANDT global headquarters on March 18 to celebrate National Ag Day behind this year's theme Sustaining Future Generations. Read More
Latest News
StewardshipBayer CropScience Announces $100K Pollinator Habitat In…
May 6, 2015
Bayer CropScience is investing over $100,000 in a project with Integrated Vegetation Management Partners, Inc. (IVM Partners) designed to improve Read More
Town & Country Co-op Smithville, OH 4R Nutrient Stewardship Certified
StewardshipThree Town & Country Co-op Facilities Certified In …
May 6, 2015
The 4R Nutrient Stewardship Certification Program has announced that Town & Country Co-op’s facilities located in Loudonville, Smithville, and Sullivan, Read More
Industry NewsMonty’s Plant Food Adds New Territory Manager
May 6, 2015
Monty’s Plant Food Co., a leader in natural soil enhancement and plant  fertility products, has hired Paul Miles as a Read More
InsecticidesVestaron’s Bioinsecticide Now Registered For Use On Mor…
May 6, 2015
Vestaron has received expanded EPA registration for its biological insect control products. These innovative bioinsecticides, which are derived from newly Read More
Sunrise Cooperative Norwalk Agronomy
StewardshipSunrise Cooperative Facilities All Certified In 4R Nutr…
May 5, 2015
The 4R Nutrient Stewardship Certification Program has announced that all four of Sunrise Cooperative Inc.’s agronomy branches, located in Attica, Read More
Crop InputsSyngenta Scientist Named 2015 National Inventors Hall O…
May 5, 2015
The National Inventors Hall of Fame (NIHF) announced its 2015 class of inductees. Among the 14 honored is scientist Mary-Dell Read More
Eric SfiligojIARC Glyphosate Report: A Closer Look At ‘Probabl…
May 5, 2015
By now, you’ve probably run across a story or two (probably closer to 100) detailing the ongoing controversy over the Read More
Syngenta
Eric SfiligojWill Monsanto And Syngenta Combine This Time?
May 4, 2015
Under the heading of “never say never,” it sounds as if crop protection/seed giants Monsanto Co. and Syngenta are once Read More
Dr. Bryan Young, Southern Illinois University, shows tour attendees a female Palmer amaranth plant.
Crop InputsPurdue Weed Scientist Publishes Weed Resistance White P…
May 4, 2015
Resistant weeds, the appropriate use of herbicides and integrated weed management strategies are highlighted topics in the new white paper, Read More
Industry NewsMonsanto-Syngenta Mega-Merger Would Drive More Deals
May 4, 2015
A combination of Monsanto Co. and Syngenta AG would set the stage for even more mergers and acquisitions, reports Brooke Read More
InsecticidesAgrian Announces New California Feature
May 4, 2015
Agrian announced today that it has developed a feature within its recommendation writing program that will support the California Department Read More
Storage Tanks at Nachurs
FertilizerNachurs Alpine Solutions: Liquid Fertilizer With Precis…
May 4, 2015
When it comes to fertilizer options in 2015 and beyond, ag retailers are taking a long, hard look at liquid. Read More
West Central Sac City growers
StewardshipIowa Lawsuit Challenges Ag’s Water Quality Efforts
May 3, 2015
Nutrient problems in west-central Iowa’s water supply made national headlines in March when the Des Moines Water Works (DMWW) filed Read More
Tim Hassinger Dow AgroSciences President and CEO
Crop InputsDow AgroSciences: Always About Agriculture
May 2, 2015
When you consider their respective backgrounds, it’s little wonder why Dow AgroSciences and new President/CEO Tim Hassinger ended up together. Read More
Nozzle spray close-up
AdjuvantsSpray Drift Enters More Complex Era
May 1, 2015
Off-target movement of crop protection products has been a problem for decades. The issue got more contentious when glyphosate-tolerant crops Read More
Crop InputsTop 10 Twitter Pics For #Plant15
April 30, 2015
Growers and ag retailers are working feverishly to plant this year’s crop. Fortunately, many of them still have time to Read More
ManagementIowa Retailer Sticks Up For Agriculture and New Spray D…
April 30, 2015
Paul Schrimpf and Eric Sfiligoj talk about how one Iowa ag retailer is working to defend agricultural practices and an Read More
Dow AgroSciences Logo wall
Seed/BiotechNew Soybean Trait Agreement To Use Dow AgroSciencesR…
April 30, 2015
Dow AgroSciences LLC, a wholly owned subsidiary of The Dow Chemical Co., Arcadia Biosciences, Inc. and Bioceres, S.A. have formed an agreement Read More