How To Minimize Phosphorus Losses In Runoff

Phosphorus losses from agricultural fields can be divided into three categories:

  • Flash losses of soluble phosphorus soon after application of fertilizer or manure.
  • Slow leak losses of soluble phosphorus.
  • Erosion events.

Flash Losses Of Soluble Phosphorus

Manure, like fertilizer, has a vastly higher concentration of soluble phosphorus than soil does. If a rainfall runoff occurs soon after a surface application, the concentration of soluble phosphorus in the runoff can be more than 100 times higher than normal in the runoff.

Over time, highly soluble manure and fertilizer phosphorus on the soil surface will react with the soil, reducing soluble phosphorus in runoff back to initial levels. Normal levels return over the course of a month in warm soils, longer in cold soils. Manure and fertilizer application is not recommended on frozen or snow-covered soils because phosphorus never has a chance to react with the soil before runoff occurs.

Research from Arkansas on poultry litter and swine manure applied to pastures shows that soluble phosphorus concentrations increase in direct proportion to increasing application rate in these flash phosphorus loss events.

Flash losses of soluble phosphorus have high concentrations of phosphorus in a form that is readily available to aquatic organisms. These events occur only if rainfall runoff occurs soon after a surface phosphorus application or when phosphorus is surface applied to frozen or snow-covered fields. However, one ill-timed application can contribute more phosphorus to surface water than is lost by all other processes over the course of a year or more.

To minimize flash losses of soluble phosphorus:

  • Apply phosphorus sources below the soil surface in a manner that does not increase soil erosion.
  • Surface-apply phosphorus sources during periods of the year when runoff is unlikely.
  • Surface-apply phosphorus sources only on fields with a low potential for runoff.
  • Do not surface-apply phosphorus sources to frozen or snow-covered soils.
  • Maintain low-phosphorus buffer strips around water resources.
  • Add alum or a similar treatment to manure to reduce the availability of phosphorus.

Slow Leak Losses Of Soluble Phosphorus

All soils naturally release some soluble phosphorus into surface runoff. The concentration of soluble phosphorus in runoff is affected by the soil test phosphorus level of the soil.

Soil tests for phosphorus were developed to help estimate phosphorus fertilizer requirements for crops. Research on soils from other states indicates that soils near optimum soil test levels for growing crops typically support soluble phosphorus concentrations of 0.5 ppm or less.

There is substantial evidence that soluble phosphorus concentration in runoff will increase linearly with increasing soil test phosphorus levels. This linear relationship changes from soil to soil. Tripling soil test phosphorus above the high soil test category may increase soluble phosphorus in runoff to 0.5-2.5 ppm.

Slow leak phosphorus losses are important because they occur in every runoff event. Because of the cumulative effect of multiple runoff events, this mechanism can be the most important source of phosphorus loss. To minimize slow leak losses:

  • Apply phosphorus only to fields that have an agronomic need for phosphorus.
  • Reduce the amount of annual runoff from agricultural fields through crop selection and soil conservation practices.
  • Maintain buffer strips where no phosphorus is applied around water resources.

Erosion Losses

When runoff water gains sufficient energy to cause soil erosion, the amount of phosphorus lost from the field increases dramatically. Controlling erosion losses by reducing or eliminating tillage on corn or wheat can reduce total phosphorus losses by 50 percent or more.

In soil, the total phosphorus is much higher than the soluble phosphorus content. Soil particles have a tremendous capacity to fix soluble phosphorus, allowing only a small proportion of the plant-available phosphorus to exist in the soluble form.

The sorting of soil particles that naturally takes place during erosion results in the soil particles with the highest phosphorus concentration being carried with runoff. Soils with higher soil test phosphorus levels will have higher phosphorus content in eroded particles. To minimize erosion losses of P:

  • Adopt soil conservation practices to minimize soil erosion.
  • Maintain buffer strips around water resources where no phosphorus is applied.

Source: University of Missouri Extension

Leave a Reply

One comment on “How To Minimize Phosphorus Losses In Runoff

  1. A typical comment from CropLife – Not a single comment regarding the all important role microorganisms play in making phosphorus available to plants thus reducing the amount of P needed. There is a limited amount of P on the planet. One country controls 60 % of the know source of P. Five years ago the price increased 800 percent. Most countries that have P deposits have increased their export fees. So what does Crop Life talk about ? Erosion loss And slow leak .

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
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
Confluence of St. Croix and Mississippi Rivers in Minnesota
StewardshipAgricultural Runoff Among Causes Of Water Quality Issue…
April 30, 2015
A new report released April 29 by the Minnesota Pollution Control Agency provides additional evidence that agricultural and urban runoff Read More
EquipmentTop 30 IRON WORKS Cartoons Of All Time
April 29, 2015
When CropLife IRON first started publishing more than a decade ago, long-time Publisher Al Strohmaier decided to start a cartoon Read More
StewardshipCPS-Hillsboro Becomes First ResponsibleAg Certified Fac…
April 29, 2015
Unlike a race where the first finisher takes home a medal or blue ribbon, safety and regulatory compliance doesn’t often Read More
HerbicidesWeed Scientists Offer New Definition For ‘Superwe…
April 28, 2015
The Weed Science Society of America (WSSA) has joined with six sister organizations to recommend a new definition for superweed Read More
Crop InputsValent Announces “Relentless As You’ Contes…
April 28, 2015
Valent U.S.A. Corporation today announced the winners of its national “Relentless As You” contest, which recognized the relentless spirit of Read More
HerbicidesSyngenta’s Acuron Secures EPA Federal Approval
April 28, 2015
Growers looking to control difficult weeds like waterhemp, giant ragweed and Palmer amaranth will have access to Acuron corn herbicide Read More
FertilizerSimplot’s Gal-XeONE Technology Moves West
April 27, 2015
The J.R. Simplot Co. remains committed to creating customer value through technology. In 2013, Simplot purchased the Gal-XeONE controlled release Read More