Minimizing Nutrient Loss to Protect Resources

The UW-Discovery Farms program analyzed how a no-till cropping system with tile drainage

impacts sediment loss and water quality.

In support of their position as environmental stewards, the Koepkes often offer their farm as an

educational classroom for farmers and public officials.

Many positive terms—innovator, leader, steward, teacher—describe the Koepkes, who farm

about 1,000 acres and milk 320 cows north of Oconomowoc. Brothers Jim and David, along with

Jim’s son, John, and his wife, Kim, operate Koepke Farms. Brother Alan is retired but is still

involved in the business.

As environmental stewards, the Koepkes have a long history of implementing soil conservation

and manure management practices. As innovators, they were among the first Wisconsin farmers

to adopt 100% no-till farming. As teachers, they serve as a no-till farming resource, guiding other

farmers and public officials. And, as leaders, they worked with the UW-Discovery Farms to gather

data about how their no-till cropping system with tile drainage and surface-applied manure affect

water quality and soil organic matter. The data collected during the study will be used to develop

best management practices to reduce nitrogen and phosphorus runoff from agricultural lands.

Jim, who leads the cropping enterprise, says, “The goal has always been to find knowledge that

will help all farmers do a better job caring for our cows and natural resources. Every day is Earth

Day when you make your living from the land.”

With no-till farming, crops are grown without disturbing the soil. No-till creates a thick mat of plant

residue that retains and infiltrates water, which helps crops grow.

Koepkes, like most farmers, realize that their farming practices impact so much more than the

land they crop. Their land, which lies in Waukesha and Dodge counties, is in the Ashippun River

subwatershed and drains southwest toward the Rock River. Surface water runoff from this

watershed eventually drains to the Mississippi River and ultimately the Gulf of Mexico.

Corn stover—or residue—helps retain water and adds organic matter to soil, essential in no-till


Like many farms in southeastern Wisconsin, poorly drained soils, dense glacial materials and a

seasonally high-water table make growing and harvesting crops difficult. Thus many of these

farmers, including the Koepkes, install agricultural tile drainage to move water more quickly

through the soil profile and out of fields. By removing excess water from poorly drained areas, tile

drainage helps minimize surface nutrient loss, protects natural resources, facilitates field

operations and increases crop yield and quality.

With soil quality a high priority at Koepke Farms, Jim likes to compare soil to a checkbook. “We

draw out of it, but we need to put back into it, too. We have a responsibility as farmers to see to it

the check doesn’t bounce.”

Based on the data collected at Koepke Farms from 2003-2009, UW-Discovery Farms researchers


For almost all surface runoff events, surface flow did not occur until the tile line was discharging

at or near full capacity.

The majority of surface sediment loss was associated with single (large) storm events. During the

monitoring period, 84% of sediment loss occurred during two storm events.

Of all rainfall that occurred on non-frozen ground, only 15% resulted in surface runoff—with most

in high moisture soils.

The no-till system at Koepke Farms limits the transport mechanism of soil loss by retaining water

and allowing for soil infiltration, which reduces sediment loss.

Tile flow was less in April, May and June under established alfalfa (a perennial flowering plant in

the pea family—cows eat alfalfa) compared with tile flow under corn. Establishing a cover crop

may help reduce tile flow volume and resulting nutrient loss in early spring.

These conclusions will help UW-Discovery Farms researchers and Wisconsin farm families

develop and implement best management practices for a sustainable future.

Visit the UW-Discovery Farms website for a complete summary of research done at Koepke

Farms. In addition, visit “Dairy Farmers are also Award-Winning Conservationists” to read about

the Koepkes and the Leopold Conservation Award.

Info derived from:

Natalie EndresMinimizing Nutrient Loss to Protect Resources