Conservation officials stress value of cover crops

DYSART - Though the state's nutrient reduction strategy is voluntary, 'cover crops are not optional,” said Ray Archuleta, a soil specialist with the Natural Resources Conservation Service and the featured speaker Thursday at a conservation field day held in the heart of seed corn country.

Cover crops, which keep living roots in the soil when corn and soybean fields would otherwise be barren, are the key to improving soil health, reducing applications of nitrogen fertilizer and improving the quality of surface water, Archuleta told more than 100 attendees of the field day sponsored by the Soil and Water Conservation Districts of Tama and Benton counties.

The field day, held on John and Brian Weber's Valley Lane Farms just west of Dysart, underscored the benefits of cover crops and saturated buffers in reducing the volume of nitrates and phosphates polluting Iowa waters and creating a dead zone in the Gulf of Mexico.

The Webers' farm is part of the Benton/Tama Nutrient Reduction Demonstration Project, which spans the watersheds of Rock, Pratt and Lower Wolf creeks, all tributaries of the Cedar River.

As part of the project, participants are sampling tile water each week at 12 undisclosed locations to establish a baseline for nutrient pollution, project coordinator Bruce Gardner said.

One of the project's supporters, the Sand County Foundation of Madison, Wis., got involved not just to help reduce nutrient pollution but also to reduce the impact of future floods along the Cedar River and especially in Cedar Rapids, said Craig Ficenec, the foundation's program director.

The attendees were able to examine the working apparatus of a saturated buffer that was installed last week on the Webers' farm.

The system, described as the least expensive means of reducing nitrates draining from tile lines, reroutes part of the flow into a shallow lateral line that runs parallel to Rock Creek.

'Water seeps out of the line where it will be taken up by the roots of the perennial vegetation in the buffer, and organisms in the soil will turn nitrates into nitrogen gas that escapes harmlessly into the air,” USDA soil scientist Dan Jaynes said.

The nitrate level in the tile water is well above the minimum drinking water standard of 10 parts per million, according to Jaynes. The water seeping from the buffer into the creek contains practically no nitrate, Jaynes said.

Attendees also observed the new growth of cover crops applied aerially over standing seed corn on Sept. 8.

Nearly a quarter-inch of rain fell on the field immediately after the seeding, ensuring excellent germination, Gardner said.

While such practices are beneficial, Archuleta called them 'reactive rather than proactive.”

'If you really want to reduce nutrient pollution, you have to improve the health of your soil, which will allow you to grow profitable crops with much less supplemental fertilizer,” he said.

Farmers need to stop treating their soil like a growing medium and start treating it like a healthy ecosystem, he said.

NRCS soil scientist Rick Bednarek urged farmers to adopt no-till cultivation practices and cover crops to improve the health of their soil.

'When we till, we destroy the structure of the soil and disturb the environment for beneficial microbes,” he said.