Vertical tillage is not no-till
Iowa conservationists with USDA’s Natural Resources Conservation Service are disturbed by the number of row crop farmers using vertical-tillage tools. Vertical tillage often leaves the soil covered with crop residue, but it is not the same as true no-till.
Vertical-tillage equipment is used to lightly till the soil and cut up crop residue, mixing and anchoring a portion of the residue into the upper few inches of soil while still leaving large quantities of residue on the soil surface.
• Farmers need to understand that vertical tillage is not the same as
• Tillage destroys the structure of soil, making soil more susceptible to erosion.
• No-till is Iowa’s most important practice in the fight against soil erosion.
Several NRCS soil conservationists say they’ve spoken with farmers who practice vertical tillage on D slopes (9% to 14% slope), and the farmers refer to it as no-till when it is a different practice altogether.
“There is a lot of misinformation out there,” says Curt Donohue, district conservationist with NRCS in Newton. “One pass with a tillage tool, even with high amounts of residue remaining, can dramatically increase soil loss.”
Soil structure destroyed
Barb Stewart, state agronomist for NRCS in Iowa, says that although vertical tillage leaves large amounts of crop residue cover, the tillage impacts are significant. “Soil-disturbing activities, like tillage, destroy soil structure,” she says. “When this happens, it limits a soil’s ability to function properly and leaves topsoil susceptible to erosion on steeper slopes.”
Kevin Kuhn, area resource conservationist for NRCS in Atlantic, says when soil is disturbed, the soil structure and habitat for soil organisms gets destroyed, water infiltration is reduced, runoff is increased and productivity declines. “Tillage disrupts the soil’s natural biological cycles and wrecks the structure of the soil, making it susceptible to erosion,” he says.
Kuhn says no-till is Iowa’s most important conservation practice against soil erosion. “I don’t want to knock vertical tillage because it’s good at leaving residue cover,” he adds, “but the goal of no-till is to reduce surface disruption, and therein lies the difference between the two practices.”
No-till is most important for erosion protection on steeper slopes. During heavy rains in April, Donohue says no-till fields had relatively minor erosion compared to tilled fields. “Even fields with high residue levels where vertical-tillage tools were used had extreme sheet and rill erosion and relatively severe ephemeral erosion compared to no-till fields,” he notes.
Stewart says no-till alone is often not enough to eliminate erosion on steeper slopes, but that a combination of practices, such as no-till, contour farming, contour buffer strips, terraces, grassed waterways and field borders need to be established to truly slow down the erosion process. “During April’s heavy rains, we saw several instances of sheet and rill erosion on steeper slopes where there was no tillage,” she says.
Stewart also recommends cover crops as a practice that can help protect against erosion during the winter and early spring.
Stay in compliance
Since 1995, conservation compliance has been a requirement of all USDA farm program participants. Any tillage not accounted for in a conservation plan may put you as a farmer out of compliance with erosion provisions.
Don Carrington, NRCS resource conservationist in Des Moines, says if a farmer makes a full-width tillage pass through a field when no-till is required, that farmer may no longer be compliant with the highly erodible land provisions of the farm bill. Carrington recommends farmers check with their local NRCS office before:
• using any new tillage equipment
• conducting any tillage if the farmer’s conservation plan calls for no-till
• fixing small gullies on highly erodible land from ephemeral erosion
Johnson is public affairs specialist with USDA NRCS in Des Moines.
TRUE NO-TILL: Corn grows well in a long-term no-till field in Carroll County in west-central Iowa. True no-till means no soil disturbance.
VERTICAL TILLAGE: Here’s an example of vertical tillage where a lot of crop residue is left to cover the soil, but the equipment disturbs the soil enough to affect soil structure.
This article published in the July, 2012 edition of WALLACES FARMER.
All rights reserved. Copyright Farm Progress Cos. 2012.