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

HerbicidesAdjusting To The New Reality Of Weed Control
November 4, 2014
Even with new cropping systems being readied for market introductions, weed control will remain a challenge for many. Read More
StewardshipResponsibleAg Begins Auditor Training
October 31, 2014
ResponsibleAg auditor training is now underway at the Ford B. West Center for Responsible Agriculture in Owensboro, KY. Read More
InsecticidesNew Research Study Shows The Value Of Neonics
October 29, 2014
The study evaluated seed treatment, soil and foliar uses of neonicotinoid insecticides in the U.S. and Canada. Read More
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
Seed/BiotechMonsanto Offers New Support For Ferguson, Area Communities
October 8, 2014
Monsanto Co. has committed $1 million in new support for several collaborative efforts in Ferguson, MO, and surrounding communities in North St. Louis County. Read More
Seed/BiotechUnapproved Genetically Modified Wheat Found In Montana
October 3, 2014
USDA reports that one year after discovery of Monsanto's unapproved wheat in a single Oregon field disrupted U.S. wheat export sales, the GMO wheat has again been found in Montana. Read More

Latest News

soybean field
Crop InputsABM Patents Microbial R&D Technique
November 25, 2014
Focused Microbial Diversity (FMD) is a newly patented technique employed by Advanced Biological Marketing (ABM) to research and develop microbials that will be used in ABM products Read More
Crop InputsStorage Options Help Grain Growers Go To Market
November 24, 2014
While on-farm storage in a traditional upright storage bin is one possibility for storing grain, it may not be for everyone. Read More
Eric SfiligojGiving Thanks For Another Great Year
November 24, 2014
As Thanksgiving Day 2014 arrives, agriculture has plenty to be thankful for. Read More
Crop InputsSyngenta Cost-Cutting Program To Affect 1,800 Jobs
November 24, 2014
The company's Accelerating Operational Leverage program will result in job reductions and relocations totaling around 1,800 across the company, the majority of which will occur in 2015. Read More
EquipmentAGCO Announces Operator Of The Year Finalists
November 20, 2014
Four custom applicators have been selected by AGCO Application Equipment as finalists for 2014 Operator of the Year, an honor that recognizes them as being among the top professionals in their industry throughout North America. Read More
MicronutrientsH.J. Baker Expands Tiger-Sul Business
November 20, 2014
H.J. Baker has created and filled two strategic positions in business development and sales within its Crop Performance Division. Read More
soybean field
FertilizerGeneral Mills Honors United Suppliers For Nitrogen Opti…
November 19, 2014
United Suppliers winning proposal detailed SUSTAIN, a consulting network that provides customized products and services for farmers using a needs-based system approach. Read More
EmployeesOhio AgriBusiness Association Awards $25,000 In Scholar…
November 19, 2014
Each year, the Ohio AgriBusiness Association Educational Trust scholarship program awards scholarship dollars to students enrolled in an agriculture-related field attending several state colleges. Read More
ManagementServi-Tech Names New CEO
November 17, 2014
Servi-Tech has named Greg Ruehle its new president and CEO. Read More
CropLife 100Pinnacle Ag Acquires Colorado Aerial Application Outlet
November 17, 2014
Ft. Lupton, CO-based Reck Aviation — a full-service chemical application company providing aerial crop applications of fertilizers and crop protection products — will operate as part of Pinnacle's AgOne Application Services brand. Read More
Eric SfiligojMcDonald’s Message: Biotech Crops Scarier Than Cancer
November 17, 2014
Despite their potential health benefits, one of the world’s largest potato users will pass on a new biotech offering. Read More
MicronutrientsWinField Releases 2014 NutriSolutions Results
November 14, 2014
A number of significant regional and national crop deficiency trends emerged from the 2014 WinField NutriSolutions tissue sampling program. Read More
FertilizerH.J. Baker Opens Chinese Production Lines
November 14, 2014
The occasion was the official launch of the Tiger-Sul sulphur Bentonite production line of two much anticipated fertilizer products in China, T90CR sulphur fertilizer and TZinc micronutrient enhanced sulphur fertilizer. Read More
ManagementOhio Certified Crop Adviser Program Accepting Nominatio…
November 14, 2014
The award recognizes an individual who delivers exceptional customer service for farmer clients in nutrient management, soil and water management, integrated pest management and crop production in Ohio. Read More
HerbicidesSyngenta Announces Acuron Trial Plot Results
November 14, 2014
Acuron was tested at 167 trial locations across 35 states. Trials included 95 Syngenta locations, 54 university locations and 18 distributor locations. Read More
Crop InputsVerdesian Expands Sales Force
November 13, 2014
The new sales representatives will work with growers, retail partners and distributors to oversee technical training and product education. Read More
EquipmentAGCO Raises $100K For Wounded Warrior Project
November 13, 2014
AGCO Corp. partnered with local AGCO dealers across the U.S. and Canada to raise nearly $100,000 in support of wounded service veterans. Read More
HerbicidesDow AgroSciences Announces Launch Of Enlist Duo Herbici…
November 12, 2014
It will be launched in conjunction with a stewarded introduction of Enlist corn, and seed production of Enlist soybeans in 2015. Read More