Management impacts on phosphorus loss with surface runoff

Extension Lead(s)
(name, position, counties served, contact information)

Antonio P. Mallarino, Profesor. 3216 Agronomy Hall, 515-294-6200,

Your Position


POW # and Team

 ­­­­­_____100 Corn and Soybean Production and Protection
­­­­­_____ 110 Dairy
­­­­­_____ 120 Farm and Business Management
­­­­­_____ 130 Horticulture: Commercial and Consumer
­­­­­_____ 140 Iowa Beef Center
­­­­­_____ 150 Iowa Pork Industry Center
­­­­­__X___ 160 Natural Resources and Stewardship
_____170 Pesticide Applicator Training
_____180 Other ANR Programs

ANR Priority (select all that apply)

­­­­­_____Global Food Security and Hunger
­­­­­_____Regional Food Systems
­­­­­__X___Natural Resources & Environmental Stewardship
­­­­­_____Food Safety
­­­­­_____Sustainable Energy – Biofuels & Biobased Products
­­­­­_____Climate Change

Title of Success Story

Management impacts on phosphorus loss with surface runoff

Continuing Story

__X___ No                _____  Yes (If continuing, what story?)

Knowledge Areas: (USDA categories)


Desired Changes

Learning and demonstrating impacts of tillage and nutrient management practices on phosphorus loss with surface runoff

(Why is it important to address this issue with education?  What are the desired changes?)

Phosphorus application to soil is necessary to maintain profitable crop and animal production. However, excess input and inappropriate fertilizer or manure application increase phosphorus loss from fields, which is a wasteful use of a non-renewable resource and pollutes water resources. Learning, demonstrating,  and educating about the degree in which different management practices affect phosphorus loss should improve farm profitability and reduce water quality impairment in Iowa

(Outputs: activities, numbers reached, publications, products)

Field demonstrations were conducted at the ISU Research and Demonstration Farm located in O'Brian county. The demonstrations consisted of implementing and measuring phosphorus loss from nine different combinations of management practices and focused on impacts of tillage system (chisel/plow and no-till) and inorganic fertilizer or swine manure phosphorus management systems for corn-soybean rotations and continuous corn. There was a field day attended by about 120 persons, a progress report was published in hardcopy and web forms within the annual reports for the Northwest Research and Demonstration Farm, there was an ISU press release, a presentation to about 500 persons during the Extension ICM conference, and a presentation to about 90 persons at the Mason City Crop Advantage Series conference.

RESULTS (Outcomes:  specific changes that occurred in Learning, Actions, Conditions; how outcomes were measured)

The demonstrations confirmed the value of no-till management to reduce soil erosion, that soil and phosphorus loss are much larger during the corn year after soybean compared with continuous corn or in the soybean year after planting corn, that no-till management usually decreases the total phosphorus loss but increases the proportion of dissolved phosphorus, which is readily available for algae in water bodies, and demonstrated no clear or consistent differences between management systems based on inorganic fertilizer or injected swine manure applied at rates currently recommended.

Public Value (now or future)
(Impact:  Who benefits beyond participants and how?  What conditions changed?)

The results and publications have been used and will continue to be used as resources in several Extension education programs. The demonstration of larger soil and phosphorus losses during the corn year after planting soybean is useful to target mainly soybean residue management as a way to reduce soil and phosphorus loss from producers' fields and improve both farm economy and water quality in the state.

Major Partners or Collaborators

Iowa Department of Agriculture and Land Stewardship, Iowa Water Center, Iowa State University Research and Demonstration Farms

Where story took place
(Region, campus, multi-regional)


Fiscal Year


Multi-state or Integrated (Ext + Research)


Funding Source

Iowa Department of Agriculture and Land Stewardship, Iowa Water Center, Iowa State University Research and Demonstration Farms


Nutrient management, Phosphorus, Water Quality, Soil Conservation


Page last updated: July 8, 2011
Page maintained by Julie Honeick,