Farmersí Knowledge of Soil Tests Increases both Profits and Water Quality

Name and Position/Title:
Brian Lang, Field Agronomist

Fiscal Year Submitted:

POW Title and Number:
104 Soil, Water and Nutrient Management

Farmers’ Knowledge of Soil Tests Increases both Profits and Water Quality

A leading cause of surface water impairment is high Phosphorous (P) levels causing eutrophication.  The consequences of eutrophication include algal blooms, low levels of dissolved oxygen, fish kills, turbidity, and shifts in plant and animal populations in surface waters.  Soil tests are an important guide for applying proper levels of fertilizer for crop production, however, most farmers do not understand how to read and interpret a soil test.  Most rely on the fertilizer suppliers, and many fertilizer suppliers over apply these nutrients to rather than follow Iowa State University fertilizer recommendations.

What Did You Do?
In the winter of 2010, the ISU Extension Agronomist in northeast Iowa initiated a pilot project with farmers, conducting a few sessions on how to read and interpret soil test reports.  The combination of increasing public concerns with water quality and the doubling of fertilizer costs to farmers over the last 5 years spurred farmer interest in obtaining a better understanding of nutrient management on their farms.  Three sessions were conducted this winter with groups of about 20 farmers each.  Farmer’s own soil tests were used to explain how to reads them, and various scenarios of cropping practices were used to illustrate how to make fertilizer recommendations.  The main goals of each session were to make sure that every farmer in attendance gained a comfortable understanding of what optimum soil test levels are and how to maximize the farmer’s rate of return to fertilizer applied.  In turn, most farmers would increase profits per acre while decreasing the amount of fertilizer applied to their fields.

Pre-meeting surveys found that only 4% of attendees thought they had an adequate understanding of how to read soil tests and make fertilizer recommendations. Post-meeting surveys brought that level up to 91%.  The remaining 9% were pleased with the information presented, but still wanted to follow their fertilizer suppliers’ programs.  The 61 attendees represented 52,300 acres of cropland.  With the knowledge gained by farmers from this program, they will be able to reduce P fertilizer applications by an average of 38% compared to their fertilizer suppliers’ recommendations.  This reduces farmer costs by about $13 per acre or just over $11,000 for the average farm.  The program succeeded with a win-win situation for farm income and water quality with reduced amounts of P fertilizer applied, both benefiting local communities.  Intentions are to continue this program over the next few years.

Page last updated: July 19, 2011
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