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

Trending Articles

CropLife 100CHS To Build $3 Billion Fertilizer Plant In North Dakota
September 5, 2014
The fertilizer plant in Spiritwood will be the single largest investment in CHS history, as well as the single largest private investment project ever undertaken in North Dakota. Read More
EquipmentNew Holland Acquires Miller-St. Nazianz
September 3, 2014
The assets of Miller acquired as part of the transaction will become part of New Holland Agriculture, a CNH Industrial brand, building on a successful four-year partnership between the two companies. Read More
CropLife 100Pinnacle Acquires East Kansas Chemical
September 2, 2014
Ranked 82nd on the CropLife 100, East Kansas Chemical will operate as part of Pinnacle's Performance Agriculture brand. Read More
MAGIE 2014 ShowStopper
EquipmentJohn Deere Again Wins MAGIE ShowStopper Award
August 25, 2014
For the second consecutive year, John Deere was honored at the Midwest AG Industries Exposition (MAGIE) for its new R4045 sprayer. Read More
ManagementExpert To Discuss Farmland Value, Rent At Farm Science Review
August 18, 2014
While cropland values in Ohio increased in the past two years, they have remained flat in 2014, declining in some cases, according to an Ohio State University agricultural economist. Read More
EquipmentAdvance Your Technology IQ At MAGIE
August 13, 2014
The Midwest AG Industries Exposition (August 20-21) is the place you need to be to see, study and evaluate how new advances in the equipment, operations, crop protection and fertility sectors can help your business prosper. Read More

Latest News

Seed/BiotechUSDA Approves Enlist Following Rigorous Review
September 18, 2014
Dow AgroSciences now awaits EPA registration of Enlist Duo herbicide, the companion herbicide to the Enlist traits, which is expected in the near future. Read More
BlendersYargus Appoints New Plant Manager
September 18, 2014
Steve Shaffer will direct and coordinate daily operations at the company’s Marshall, IL, manufacturing plant, where the Layco line of material handling equipment is produced. Read More
CropLife 100Pinnacle Acquires Kansas-Based Cedar Ridge Supply
September 16, 2014
Cedar Ridge Supply will operate as part of Pinnacle's Performance Agriculture brand. Read More
StewardshipSecretary Vilsack Highlights Innovative Conservation Ef…
September 15, 2014
Nearly $16 million in Conservation Innovation Grants (CIGs) will be awarded to 47 organizations to help develop cutting-edge ideas to accelerate innovation in private lands conservation. Read More
Seed/BiotechSyngenta Responds To Cargill Lawsuit
September 15, 2014
Syngenta believes that the lawsuit is without merit and strongly upholds the right of growers to have access to approved new technologies. Read More
Equipment2014 Farm Science Review Launches Mobile App
September 15, 2014
Smartphone and tablet users planning on attending the 2014 Farm Science Review can now download this year’s customized mobile application. Read More
CropLife 100Southern States Coop Grower Sets Georgia Soybean Yield …
September 15, 2014
Georgia farmer Randy Dowdy's soybeans yielded an astonishing 110.66 bushels per acre, crushing the previous record of 82 bushels-per-acre. Read More
NIMITZ Treated vs Untreated pepper plant
InsecticidesNIMITZ Nematicide Approved By EPA
September 12, 2014
NIMITZ is a novel, non-fumigant nematicide with simplified application features, user safety and an active ingredient with a unique mode of action. Read More
InsecticidesMarrone Bio Innovations Receives Patent For Chromobacte…
September 11, 2014
The patent is the first step for MBI in developing a commercially viable product to inhibit infestations of corn rootworm larvae across America and other regions. Read More
HerbicidesDow AgroSciences: Keeping The Pipeline Stocked
September 11, 2014
Dow AgroSciences is embracing product diversity to drive the company’s future. Read More
CropLife 100CHS Is Official Partner Of New St. Paul Ballpark
September 10, 2014
The new ballpark in St. Paul, MN, officially became CHS Field with Twin Cities-based CHS Inc. revealed as the naming rights partner. Read More
EquipmentHagie Honors Farming Stewardship Leaders
September 10, 2014
The Iowa Farm Environmental Leader award recognizes Iowa farmers as environmental leaders that are committed to healthy soils and improved water quality. Read More
Precision AgPlantBeat: Your Plants’ Pulse In The Palm Of Your Han…
September 10, 2014
A new agronomic monitoring and recommendation service from Phytech could rewrite the book on real-time plant health status monitoring. Read More
StewardshipCCAs Making Headway With 4R Program In Lake Erie Wester…
September 9, 2014
Certified Crop Advisers are implementing the 4R Nutrient Stewardship Certification program in Lake Erie's Western Basin to improve water quality. 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
Crop InputsFMC Announces Cheminova Takeover
September 8, 2014
FMC Corporation today announced that it has signed a definitive agreement to acquire Cheminova, a wholly owned subsidiary of Auriga Industries. Read More
HerbicidesValent’s Fierce XLT Herbicide Receives EPA Approv…
September 8, 2014
Valent U.S.A. Corp. announced today that Fierce XLT Soybean Herbicide is now federally registered for preemergence weed control in soybeans Read More
Eric SfiligojIndustry Consolidation Set To Increase Going Forward
September 8, 2014
As the agricultural marketplace moves into fall, one observer predicts the pace of consolidation will grow at all levels. Read More