Making the switch from tillage to zero till requires big changes in the way a farmer thinks and works and especially how he reacts to problems such as weeds, diseases and pests, says Dwayne Beck, manager of the Dakota Lakes Research Farm near Pierre, South Dakota.
The veteran no-tiller said farming systems are made up of cultural practices, technology and management, while cultural practices can be broken down into tillage, rotation, sanitation and competition.
“We have to quit doing tillage. There isn’t a choice. We can’t afford it, it’s too destructive,” Beck said, adding that tillage is a “catastrophic event” that doesn’t occur in nature.
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“Tell the organic guys that what they are doing is not natural. It’s not sustainable.”
Beck, who has been farming no-till since the late 1970s, said that tillage is a cultural practice that can be replaced through other approaches.
“Most people, when they quit doing tillage, they try to replace it with technology,” he said. “But we need to replace tillage with other cultural practices because there is not enough technology available to replace tillage if that’s all we use.”
Mother nature is an opportunist, he added. Farmers should ask themselves every time they have a problem what they did to give a weed or a pest the opportunity to be successful.
“Strive to produce a crop which is healthy, not a crop that doesn’t get sick.”
Accurate fertilizer placement and seeding, which fit in the competition category, can help. Minimal disturbance seeding cuts a slot through the straw cover for the crop, leaving weeds buried under the old crop residue.
Most of the plant growth problems blamed on no-till are the result of inadequate diversity or improper intensity.
“If you’ve got a weed or disease, you’re not diverse enough,” he said. “We counter Mother Nature’s efforts by adding diversity. If you don’t have it, she’s going to say, ‘here’s a weed.’ “
Beck boasted that he did not know the current price of a wild oat herbicide.
“I haven’t used any since the 1980s. I don’t have to because I have added diversity of my own.”
Using correct crop rotations and not stirring up the buried weed seeds allows no-tillers to eliminate problems such as wild oats naturally. Two years in a row of warm season or broad leaf crops can reduce cool season weeds such as wild oats or downy brome by 95 percent if the soil is not disturbed, he said. The same goes for warm season weeds such as green foxtail in winter wheat.
“The wheat gets harvested before it gets a chance to go to seed. So I can kill it there.”
He said researchers conducted a 12-year study at Dakota Lakes involving 15 rotations with herbicides using no-till methods. On the 13th year, they planted only spring wheat with no herbicides. A federal inspector came to count the weeds and found 94 weeds per sq. metre on wheat-chickpea, wheat-pea and wheat-canola rotations, while wheat-corn-chickpea had 40 and a four-way rotation had seven weeds per sq. metre.
“That’s 93 percent weed control, strictly with rotation,” he said.
A tilled plot nearby, with the same rotations, had 225 weeds per sq. metre on the two-crop rotation and 44 weeds in the four-crop rotation.
Tillage brings buried weed seeds to the surface where they can grow. No-tillers can beat most of the weeds after just two years of leaving the soil undisturbed, he said. The study found that only 11 percent of weed seeds on the surface are viable after two years. Survival was 28 percent at five centimetres deep and 55 percent at 10 cm deep.
Beck said that when a wheat-corn-pea or wheat-millet-pea rotation is used, by the time the rotation returns to wheat a high disturbance site will have 33 percent of the weeds left and the low-disturbance site will have four percent.
For bugs, Beck said growers should try inconsistency in both sequence and interval. In the corn-soybean belt, corn rootworm is a problem because the pest figured out that by waiting two years, it could get around the rotation that was initially introduced to break its life cycle.
“In other places, the females fly from the soybean fields to the corn fields to lay their eggs.”
Beck cited research that seems to indicate that no-till plants have higher water-use efficiency because the carbon in the soil is released slower, more gradually and at a rate matching peak plant growth with microbial activity.
Under the plant canopy, the elevated level of carbon dioxide gas allows partial closure of the stomata, which leads to less water loss under dry conditions, more efficient photosynthesis and higher yields.
“If you do tillage, the carbon goes away in four days,” he said.
Carbon needs to be put back into the soil, not taken out, he added. If the straw byproduct of corn production is used for cellulosic ethanol, he said, up to 3,000 pounds of carbon per acre will be removed from the soil in each crop year.
“We have built our agriculture on mining the organic matter of our soils,” he said.
He noted that ancient civilizations in the Amazon rainforest, which has poor soil due to heavy leaching of nutrients, were able to enhance fertility by adding charcoal to their fields.
“And here we are, the civilized ones, taking our organic matter and making it into ethanol. Maybe we should instead be fixing the degradation that we’ve done.”
