Benefits, drawbacks of "no-till" farming
No-till farming at planting time. (Courtesy Mark Liebig).
DB: This is Earth & Sky. Some farmers are trying “no–till” farming.
JB: In other words, they don’t till up the soil before planting crops. Instead, they plant seeds directly into the soil. Several studies have found that when farmers practice no–till farming, more carbon stays in the soil. Less is released into the air as the greenhouse gas carbon dioxide. So no–till farming might help reduce global warming.
DB: Mark Liebig is a soil scientist with the Northern Great Plains Research aboratory in North Dakota. He says few farmers have asked him how they can reduce their impacts on climate change.
Mark Liebig: There’s so much economic stress in farming right now. And they don’t have the luxury of saying that I want to manage my farm so that I can increase my carbon content and reduce my nitrous oxide emissions so that in 10 years, I’m going to have a real positive greenhouse gas balance on my farm or ranch. You know they may not have a 10–year window. They may be just surviving year to year.
JB: So, Liebig says, the important thing is to stress the bottom line. In many cases, no–till farming improves soil quality—reduces soil erosion—saves the farmer work—reduces the need for fertilizers and fuel—and increases crop yields.
DB: One possible drawback: with no–till farming a farmer might have to use more herbicides to control weeds. Liebig said he thinks the benefits outweigh that drawback. That’s our show. Special thanks to the National Fish and Wildlife Foundation. We’re Block and Byrd for Earth & Sky.
Scientists are still trying to determine if no–till farming also reduces other important greenhouse gases such as methane and nitrous oxide.
Randall Reeder, an agricultural engineer at Ohio State University, reviewed today’s segment. He wrote: “Tillage causes organic matter (carbon) in the soil to convert to a gas (CO2) and go to the atmosphere. In some long term research sites, the organic matter over 100 years ago was 4%, and after 50 or 75 years of plowing every year it dropped to 2%. In those same plots, where they were converted to no–till, say 25 years ago, organic matter has INCREASED. It may never reach the original 4%, but research shows it should go as high as 3.5% with continuous no–till crop production. As far as I know there has never been a situation where a farm switched from tillage to no–till and continued to lose organic matter.”
Reeder continued: “On weed control, research shows that conventional farmers (those who till) use about 98% as much herbicide for weed control as no–till farmers. Organic farmers don’t use chemical herbicides, but that is a tiny, tiny portion of our crop production. Where weeds ARE harder to control with no–till, a farmer likely would use either a little more of a particular herbicide, or more often, a second herbicide along with the ‘main’ one.”
I asked Mark Liebig what percentage of land in the U.S. is used for agriculture. He wrote, “As of 2002, it’s 46 percent (19 percent cropland, 6.1 percent pasture, and 20.9 percent rangeland). I pulled this from the ‘Statistical Abstract of the United States: 2004–2005’ (http://www.census.gov/statab/www/).”
More Quotes from Mark Liebig:
On how seeds are planted in no–till farming: “You can think of a knife that cuts a wedge out of the soil that then allows the seed to be dropped down into the soil. . . . then there’s a wheel that essentially presses that wedge together and covers up that seed. There’s no soil that comes out of the ground . . . during no–till seeding.”
On economic and environmental benefits of no–till farming: “A significant component of looking at no–till is just economics. If you can minimize the number of passes that you go over a piece of land with farm equipment, . . . that’s going to save the farmer money in the long run. And certainly with fuel costs the way they are, that’s a significant concern. Aside from the economic concerns, there are some environmental aspects that are associated with no–till that if practiced right can have a positive benefit. One of which is that if you’re not disturbing the soil, tilling the soil, disturbing the soil via tillage, you reduce your potential for soil erosion. . . . Another thing . . . is that lack of soil disturbance results in decreasing your loss of carbon to the atmosphere as CO2.”
On the bottom line: “One really important thing, from the farmer’s standpoint, is the effect that those changes in soil quality have on crop yield. There’s some evidence to indicate that as you practice these practices over a long period of time, what you find is that your crop yields increase. It can be a relatively small amount, but we’ve seen this work—our evidence of this both in North Dakota and Argentina—both semiarid environments—where farmers have been practicing a continuous crop, no–till system for 15 or 20 years, they see increases in organic matter content and all these improvements of soil quality indicators. It begins to be translated into crop yields. And that’s important because—two things—that’s affecting the farmer’s bottom line and it’s also producing more food for a growing world.”
Our thanks to:
Mark Liebig
USDA Agricultural Research Service,
Northern Great Plains Research Laboratory
Mandan, North Dakota
