“Sustainability is not an end goal,” says Alan Franzluebbers, an ecologist with USDA’s Agricultural Research Service in Raleigh, N.C.

“It’s a path.”

Farmers’ goals include productivity and profit, but protecting the environment is also important. More are doing that by converting to reduced-tillage production practices, Franzluebbers said during a presentation to the annual No-till Oklahoma Conference in Norman.

“Farmers start with no-till systems,” he said. “Then they add cover crops over time to achieve sustainability goals. They need cover crops and a diverse rotation program that provides benefits to the soil and the crops.”

He’s worked with various systems in both North Carolina and previously at the USDA’s Watkinsville, Ga., research center near Athens and the University of Georgia campus.

Diverse rotation systems have included corn and wheat with a clover cover crop; cotton, rye and peanuts; integrated crop and livestock systems; and agro-forestry or silva/pasture programs.

He said the climate around Watkinsville often includes water deficits in the summer and surpluses in the winter. He’s worked for several years on the interaction and the effect that livestock grazing on cover crops has on subsequent crop production.

Also evaluated in the study are different tillage systems, including conventional-tillage, short-term no-till and long-term no-till.

“Integrating livestock into crop production can create hardpan,” Franzluebbers said. “We wanted to assess cropping systems and compaction following grazing.”

He started with some assumptions, including that a cover crop would improve soil biochemical properties with or without grazing pressure while soil physical properties would be reduced.

Also assumed was that soil biological properties would be better with no-till and physical properties would be poorer with no-till.

Because of climate, yields in the studies were relatively low. Sorghum for grain yield was lower when the cover crop was grazed as was sorghum for forage. Conventional-tillage yield was lower than with no-till.