Understanding Phosphorus Versus Nitrogen Manure Management

In most cases, nutrient management plans are based on balancing nitrogen. This comes from our scientific understanding of nitrogen behavior and generally greater concerns with the environmental fate of nitrogen and the potential negative human health effects of nitrates in water.

However, phosphorus has also received significant attention because of the potential for accelerated eutrophication in water bodies receiving excess P. Phosphorus is an essential nutrient for crops. A critical component of crop production is managing phosphorus for optimum economic benefit.

However, if phosphorus is allowed to move off the land and get into water, it can be a pollution problem. Unlike nitrogen, excess phosphorus is not toxic but can result in eutrophication of water bodies. Eutrophication is the increased growth of undesirable algae and other aquatic plants, which limits the use of the water for drinking, fisheries, recreation, and industrial use. Historically, a major source of phosphorus in water was wastewater treatment plants.

But as the amount of phosphorus getting into water from this source has been reduced, agricultural sources of phosphorus have gotten more attention. Manure in particular has been identified as a source of phosphorus to the environment. Agriculture has evolved toward greater and greater specialization. Consequently, animal feed is often produced in a different location from where the animals are fed. Feed containing phosphorus is transported to the animals. However, the manure containing much of the phosphorus that was in the feed is spread locally and not recycled back to where the crops were produced. This has resulted in phosphorus accumulating in excess amounts in some areas of high animal concentration.

At the same time, we have long recognized that one of the consequences of basing nutrient management plans on nitrogen is that, in most cases, excess phosphorus will be applied to the soil because the nutrient content of manure does not match the nutrient requirement of most crops. On the other hand, if the phosphorus requirement of the crops is balanced with the phosphorus in manure, two to four times as many acres are required to utilize the manure, and nitrogen fertilizer will be required to meet the needs of the crop.

This is not an ideal situation, but from our understanding of phosphorus behavior we know that there are things that we can do to minimize the environmental impact of this excess phosphorus in many cases. Consequently, we have consistently emphasized that, while the official guidelines for manure management have been based on nitrogen, we cannot ignore phosphorus. This is the reason for including practices such as soil and water conservation, balancing manure applications over crop rotations, cover crops, etc. in nutrient management plans.

Research has shown that a majority of the phosphorus from agricultural fields lost to water comes from a limited area on most farms and from a few storm events. There are two factors that must be considered in developing effective management strategies. For nutrient loss to occur, there must be a source of phosphorus and there must be a mechanism for transporting it to the water. A key concept to effectively managing nutrient pollution is to focus on where these two factors overlap; i.e., a high source coupled with high transport.

Tools to help identify where these critical source areas are, and to suggest manure management strategies to address these areas, have been developed. See the Penn State Cooperative Extension publication, Managing Phosphorus for Agriculture and the Environment, The Pennsylvania Phosphorus Index v 2.0 for more details.

Since agriculture is changing rapidly, farm classifications may change with time. Therefore, farmers periodically should evaluate their farm’s nutrient management status to adjust their strategy as appropriate. More detailed evaluation of fields and practices will be necessary to identify specific management options or best management practices (BMPs) for each individual situation.

Source: Penn State College of Agricultural Sciences, Penn State Extension

Leave a Reply

Fertilizer Stories
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
Aerial view of the West Fertilizer explosion site
FertilizerFertilizer Companies Blame City For West, TX, Explosion
August 6, 2014
El Dorado Chemical Co. and CF Industries contend the city failed to properly train the first responders and had insufficient protocols in place to battle the April 17, 2013, blaze at West Fertilizer Co. that triggered the explosion. Read More
FertilizerThe Fertilizer Institute: New President, Renewed Energy
February 3, 2014
Chris Jahn relishes the opportunity to lead the organization through the challenging times ahead. Read More
FertilizerA New Cycle For Fertilizer Demand
January 2, 2014
Changes in the corn market could have a major impact on the crop nutrients sector in 2014, say experts. 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
Industry NewsCHS Insurance Names New Director Of Sales
April 17, 2015
Bryan Lewis has been named director of sales for CHS Insurance, the nation’s largest agribusiness insurance broker and full-service insurance Read More
Mature Waterhemp in Corn
HerbicidesGenetic Literacy Project: There’s No Such Thing A…
April 17, 2015
Read the latest “analysis” on GMOs from Consumer Reports and you’ll “learn” that glyphosate, the chemical developed by Monsanto (its Read More
HerbicidesNew Resistance To 2,4-D Discovered In Australia
April 17, 2015
In a world-first case of herbicide resistance, researchers have confirmed that sowthistle weed in the south east of South Australia Read More
ManagementNews From RTP Company Visits and Growers Buying Older S…
April 16, 2015
Paul Schrimpf and Eric Sfiligoj discuss recent trips to the Research Triangle Park area and market seed sales trends. Read More
soybean field
StewardshipNew ASABE Standard Establishes Framework For Sustainabl…
April 16, 2015
The American Society of Agricultural and Biological Engineers (ASABE) has initiated a project to develop a new standard to establish Read More
MicronutrientsSouthern States: An Inside Look At Our Tissue Sampling …
April 15, 2015
Remember learning about the food pyramid in school? The nutritional diagram recommends the proper amount of nutrients you need on Read More
Industry NewsArysta Adds New U.S. Fungicides Marketing Manager
April 15, 2015
Arysta LifeScience North America recently hired Deneen Sebastian as its Marketing Manager for U.S. Row Crops, Fungicides. Most recently, Sebastian Read More
FungicidesVerdesian Launches Phosphite-Based Cereal Fungicide
April 14, 2015
A new, phosphite-based fungicide designed for improved suppression of deoxynivalenol (DON) in wheat and barley infected by Fusarium head blight Read More
Mature Waterhemp in Corn
HerbicidesSURVEY: Close To 90% Of Growers Battle Weed Resistance
April 14, 2015
Herbicide resistance management continues to be a priority for corn and soybean growers, and they’re working together more effectively to Read More
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
StewardshipFMC Corp. Joins Sustainable Agriculture Alliance
April 14, 2015
FMC Corp. has joined Field to Market: The Alliance for Sustainable Agriculture, a multi-stakeholder initiative working to define, measure and Read More
Industry NewsArysta Adds Two To Goëmar Sales Team
April 14, 2015
Arysta LifeScience North America recently announced two new additions to the Goëmar sales team: Steve Kelly, Technical Service Manager – Read More
Valley Variable Rate Irrigation
Precision AgVariable Rate Irrigation Gains Followers
April 14, 2015
Irrigation systems have had the ability to apply different amounts of water throughout a field for decades, using timers that Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Gr…
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
Soybean field
Industry NewsThree Ag Co-ops Poised For Possible Merger
April 13, 2015
Following months of study and preparations, the Board of Directors for United Farmers Coop (UFC), Farmers Elevator Cooperative (FEC) and Read More
Eric SfiligojAgriculture Braces For More Belt-Tightening
April 13, 2015
Spring is in full bloom across the U.S. and ag retailers and their grower-customers are busily getting into high gear. Read More
ManagementPollinator Health and Washington, DC
April 9, 2015
CropLife America’s Kellie Bray speaks with CropLife Editor Eric Sfiligoj regarding bee health and proposed Beltway regulations. Read More
InsecticidesValent Takes On MGK Insecticide Portfolio
April 9, 2015
As of April 1, Valent U.S.A. Corp. became the exclusive provider of the MGK crop protection line of insect control Read More