Pollutants from farm water far fewer than stormwater
WILLMAR -- The water quality study evaluating runoff from farmland near Blomkest and stormwater from the city of Willmar shows that the farmland is contributing less pollutants, in seven of the eight pollutants measured, than the city's stormwater.
There is more nitrate coming from farmland water than from the city water, according to John Moncrief, a professor and extension soil scientist at the University of Minnesota who is coordinating the study. The results represent analysis of water samples taken in 2008 and 2009.
The eight pollutants measured include soluble phosphorus, particulate phosphorus, total phosphorous, total suspended solids, ammonium-ammonia and nitrate-nitrite, along with fecal coliform and E. coli.
Moncrief presented the results of the ongoing research Thursday at Gorans Brothers Farm near Blomkest. The farm is home to the land used in the study -- 150 acres fertilized by either turkey manure and commercial fertilizer or only commercial fertilizer and a 10-acre unfertilized control plot. Water from the farmland and stormwater from the city both flow into Lake Wakanda, south of Willmar. The area provides a unique situation where both city and farm landscapes are contributing to the water quality of the lake, which has been declining.
Moncrief also reviewed crop production results from the land, which has been planted to corn in both 2008 and 2009 and will be soybeans this year.
The ground was fertilized with commercial fertilizer and manure in the fall of 2007. In the fall of 2008, anhydrous ammonia was applied at a variable rate with the average application of 122 pounds per acre. Last fall, no fertilizer was applied.
Tillage included fall chisel plowing in the fall of 2007, spring field cultivation in the spring of 2008, moldboard plowing last spring and field cultivation before the beans are planted this spring.
The average yield for 2008 and 2009 on the fertilizer-only ground was 199 bushels of corn. The manure and fertilizer ground was 208 bushels on average. The control acres yielded 140 in 2008 and only 109 bushels per acre in 2009.
This year, the project is going to be expanded, Moncrief said. The researchers will begin installing and evaluating techniques for cost-effective nitrate reduction, such as using wetlands on the edge of Lake Wakanda and using a bioreactor, filled with wood chips, to filter the water.
Research conducted by the university in Rice County shows reductions in suspended solids, phosphorus, nitrate and E. coli.