For hundreds of years, intensive tillage, also known as conventional tillage, was the dominant method for cultivating crops in many parts of the United States, but technological advances in machinery, seed, chemical and other aspects of agriculture in recent decades have opened the door to new practices and hybrids.
The purpose of tillage is to destroy weeds, break up organic particles to increase surface area and aeration, which results in a greater rate of nitrogen mineralization, but a decrease in soil organic matter levels. Soil organic matter is composed of decomposing animal and plant tissues and residues. When crop residue and SOM break down, organisms release nitrogen for plant use in a process called "mineralization."
All of these activities are vital to crop survival and quality, but each of the different tillage systems utilize the processes and properties differently to ultimately achieve the same goal.
Article Photos
Submitted Photo --
This is a closeup look at desi chickpea growing in a no-till wheat stubble in northeastern Montana.
Intensive tillage involves the entire field being plowed, resulting in the soil being turned and leaving less than 15 percent of crop residue cover. No-till, also known as one-pass, does not use tillage to establish the seed bed and is only done at the time the seed is planted.
In between intensive and no-till is minimum-till, which leaves at least 30 percent of crop residue on the soil surface. An offshoot of minimum till is strip-till, which involves tilling alternating strips of land 8 to 10 inches wide in which to plant the seed, leaving the rest undisturbed. This method combines the soil protection offered by no-till with the warming and drying benefits of conventional tillage.
Conducted by the Conservation Technology Information Center, the Crop Residue Management survey collects information on the county and state level about the conservation, reduced and intensive tillage acres in the U.S. The most recent study, conducted in 2004, revealed that more than 620,000 of the more than 766,000 total planted acres in Ward County nearly 81 percent was done using conservation tillage practices. Of the multiple conservation tillage methods, no-till was used in almost one quarter of fields and from 1998 to 2004, the number of acres planted using no-till doubled.
On the state level, total conservation tillage practices increased from 28 percent of total planted acres in 1998 to 39 percent, or 8.2 million acres, in 2004, although the 2000 and 2002 surveys showed a slight decrease in conservation tillage practices due to the very wet conditions of the time.
Based on information from the North Dakota Agriculture Statistics Service and discussions with other Natural Resource Conservation Service area agronomists, Ted Alme, state agronomist, estimated that nearly 20 percent of Ward County and 45 percent of state-wide 2007 acres planted was done using no-till or other conservation tillage methods.
The same is true across much of the northern Great Plains.
Perry Miller, associate professor in the Department of Land Resources and Environmental Sciences at Montana State University, said that in the most recent land survey, 56 percent of dryland in Montana was no-till.
"No-till will be the new 'conventional' in the near future," Miller said.
But this was not always the case.
Making changes
Clain Jones, assistant professor in the Department of Land Resources and Environmental Sciences at Montana State University and Extension soil fertility specialist, said the main reason many farmers stayed with the "conventional" tillage method for so long was because the practice resulted in good weed management, smooth fields and simply because they already had the necessary equipment.
Farming methods began to change after the dustbowl of the 1930s and the advancements in tractor and implement technology during the first half of the 20th Century.
The 1950s saw the introduction of the no-till method of farming, Miller said, but machinery and seed technology, as well as the high cost of Roundup, then a patented item, kept the practice from becoming a viable alternative to intensive tillage.
Twenty years later, concerned with the overall health of the soil, early "no-till pioneers" as Miller called them began promoting the practice. But it wasn't until the 1980s that the method began to catch on.
"It took a long time for the education and technology to catch up," he said,"And the price of Roundup had to drop before people would consider any alternatives."
Following other conservation movements, conservation tillage took off.
"No-till was on a roll until the mid-1990s," said David Franzen, a soil science specialist at an NDSU Extension office. "But the rainy conditions into the early 2000s delayed it."
He added that minimum-till fields had been increasing during that time, but it has only been within the last three years that he has seen a dramatic increase in no-till, driven by the drought and high cost of fuel, especially from the Rugby area west to the Montana border.
Today, Jones said he believes the No. 1 reason farmers have begun to convert from intensive tillage to no-till is labor savings.
In no-till or minimum-till systems, farmers save in labor costs because they are tilling their fields less, resulting in less fuel use and wear on their machinery, allowing farmers to tend more acres with the extra time and potential savings.
The second reason for the change weather.
Because of changes in climate and moisture levels within the past five years, no-till has surpassed intensive as the method of choice for farmers in much of Montana and North Dakota.
Pros, cons
As with all things in life, there are advantages and disadvantages of each system.
The conventional method would not have stayed around as long as it has without some positive attributes. When the land is tilled, the soil is turned over and increases the availability of oxygen which results in higher nitrogen availability in the spring, Jones said, and there are also less seeding issues in conventional systems because of the reduction of residue. The lack of cover also allows the soil to reach warmer temperatures which plays an important role in emergence.
While the conventional method has its advantages, soil in tilled fields becomes exposed and vulnerable to erosion by water or wind. Even a single erosion event can remove a significant amount of nutrients, dramatically affecting crop quality and yields. In windy North Dakota, researchers found substantially more soil was removed by wind in intensive tillage versus no-till practices, especially in drier soil-types.
Along the same line, intensive tilling results in the compaction of soil and the break down of the natural soil structure, which over time hurts aeration, Jones said. Finally, the labor-intensive nature of a conventional system has also raised some eyebrows in recent years, especially with the dramatic increase in fuel and other input costs.
In research of no-till and minimum-till systems and nutrient content, Jones and other experts from the Montana State Extension office found that, for better of worse, these systems influence water filtration, soil moisture and temperature, nutrient distribution, soil aeration and microbial population and activity.
The publication, "Nutrient Management in No-till and Minimum Till Systems" found that no-till systems generally maintain or increase SOM content and the SOM is generally higher in the top 8 inches of soil than in conventional tillage systems.
The higher water content at the surface was found to promote higher root distribution near the surface, an advantage in areas that receive frequent small rains. As in nature, the residue covering the soil surface and the soil bind with plant roots, resulting in less soil erosion. With concern to fertilizer, researchers found that no-till and minimum-till systems in North Dakota made better use of medium- to high nitrogen fertilizer rates than intensive till, indicating a superior yield response to nitrogen in no-till systems.
Of course, where there is yin, there is yang. Potential drawbacks in no-till and minimum-till systems include disease carry-over from crops and poor emergence in cooler temperatures under heavy residue. There is also an issue of nitrogen being "tied-up" in the soil because microorganisms near the surface steal the nitrogen, leaving an abundance of carbon.
Researchers, however, found this to be a short-term issue. In the beginning, greater attention needs to be paid to no-till or minimum-till systems because of lower nitrogen mineralization rates and greater risk of nutrient stratification, which can hurt crop yields if the amount nitrogen is not adequate. Overall, however, researchers found little differences in fertilizer rates, placement and timing among the different tillage systems.
Machinery is also a concern because special equipment such as a no-till coulter, strip-till row unit and specialty planters is needed to make the transition and can run into the hundreds of thousands of dollars.
John Nowatzki, agricultural machine systems specialists at NDSU Extension, said although the equipment can be a large investment, the durability, consistency and precision of the machines is well worth the price tag.
Other considerations
But there are many details to consider for those interested in making the transition.
For no-till systems to operate successfully, Miller said, farmers will need to increase the number of crops in their rotation, which will reduce weed problems. In looking for additional crops, he stressed that farmers need to look for low-residue crops instead of high-residue because an over abundance of residue can harm plant growth. Jones added that small grains like wheat work best because the crop has smaller stems than crops like corn or sunflowers.
"The crop rotational aspect (of no-till systems) is more important than conventional in terms of disease, pests and weeds," Miller said, adding that the rotation should include warm and cool season crops.
The first to consider are pulses like chickpeas and lentils because, due to their large seed size, are more forgiving when it comes to seed depth. In addition to their natural ability to fix nitrogen problems, Miller said that both peas and lentils respond well to small grain residue stubble.
With those three factors, "Its a win, win, win situation," he said.
Once those are established, Miller suggests looking into oilseeds, which are very profitable if enough water is available and help to control pest and disease issues.
But not every place or crop can be no-tilled.
Two crops that can not be adapted are sugarbeets and potatoes because of the number of chemical and fertilizer applications they require and the nature of the planting, Jones said.
"In the gut of the (Red River) valley, no-till doesn't work," Franzen said," It's just too cold and wet." Instead, he said eastern North Dakota farmers have begun to adapt a strip-till method, which combines the conservation aspect of no-till by leaving strips of land untouched, with the aeration aspect of conventional tillage.
Jones said that the conversion from conventional to no-till can be done in a single season, but he said extra nitrogen would be needed for the next five to tens years depending on conditions to bring the system back into balance. He added that after 20 to 25 years, research has indicated that no-till land will need less nitrogen than intensive tilled land.
In terms of yields between the different methods, researchers are on both sides of the fence. The Montana State study did not find any significant yield differences between the no-till and conventional methods, but it did mention that some long-term studies of wheat in Canada suggested an increase in yield with the no-till method over intensive.
Research by the NDSU Extension Service found that over a five-year period, spring wheat yields increased an average of 45 percent with no-till over conventional. Soybeans also showed superior results under no-till, but yield differences were much smaller.
Trends
Regardless of the reason, trends in recent years suggest conservation tillage will continue to increase.
Franzen said he anticipates an increase in no-till adaptation in the sandy soils of the west and a gradual movement toward strip-till in eastern North Dakota, where specialty crops will benefit from farming hybrid.
Jones said with the severe drought in the west and northwestern parts of North Dakota, he predicts a heavy influx of no-till adoption, but otherwise he predicts a slow down in the overall number of farmers converting to the no-till method because he believes those who were going to adopt the method have already done so in recent years, but added that if fuel or other expenditures spike, it could entice more farmers to switch practices.
Nowatzki said he believes conservation tillage practices will continue to grow because of the increased interest of carbon sequestration by farmers in recent years and the increasing threat of climate change to the industry.
Carbon sequestration occurs in the roots, so when a field is ploughed, it releases carbon dioxide into the air, increasing greenhouse gases which have been attributed to climate changes, but conservation tillage methods reduce the amount of carbon dioxide released in the air by reducing the number of acres or times that fields are ploughed.
He added that the recent $700 billion government bailout had some "pork barrel" initiatives tied to it, including the renewal of tax credits for converting corn into ethanol and funds to encourage carbon credit trading, which will further entice farmers.
The idea of "carbon credits" came about from the Kyoto protocol, which pushed for a reduction of greenhouse gases by industrialized nations by assigning maximum emission levels. Although the United States never signed the agreement, many of the countries that did require companies who operate within their borders to adhere to the limitations outlined in the agreement by buying credits to offset their emissions.
Farmers unions in the U.S. contract with farmers who practice methods that sequester carbon in the soil and pay them a "credit" for the amount of carbon sequestered in the soil during the year. The credit is then sold to the Chicago Climate Exchange who then sells them to companies needing them, opening new conservation benefits.
Essentially, Nowatzki said, "(farmers) can make $5 to $10 an acre by doing nothing,"