How No-till Farming Works

Plowing does have its benefits, such as burying pesky weeds, aerating and warming the soil and introducing fertilizer in the form of manure and crop residues. However, it also leaves the land more vulnerable to erosion.

The Dust Bowl drove that point home when, by the end of 1934, 35 million acres (14 million hectares) of farmland had been destroyed and another 100 million acres (40 million hectares) of top­soil was blown away [source: PBS]. Tillage has taken a toll elsewhere as well: Sub-Saharan African soils lose nutrients at an average of 21 pounds per acre (9.5 kilograms per 0.4 hectare) per year due to erosion, and the cost of land degradation in South Asia amounts to $10 billion per year [source: FAO].

­But where tilling has a deleterious effect on the soil -- reducing organic matter by an average of 256 pounds per acre (116 kilograms per 0.4 hectare) per year in some cases -- no-till farming can actually lead to increases in organic matter [source: Fawcett and Caruana]. As a form of conservation agriculture, a name used to describe farming methods that preserve the natural inputs involved in farming, no-till methods allow the soil to rebuild itself through the slow decomposition of the previous crop's residues. Where tilling disturbs, no-tilling restores.

The conservation of organic matter provided by no-till farming is one of its key benefits. Soil is, after all, what makes or breaks a crop's productivity -- it's the currency upon which agriculture depends. Organic matter, the element of the soil that comes from plants and animals, is part of what makes that currency so valuable. Allowing the soil to undergo the natural processes of decomposition -- letting previous crops break down into their composite nutrients and permitting worms to wiggle around -- is one of the best things you can do for it.

Preservation of organic matter isn't the only benefit of no-till farming. It's also an effective deterrent to runoff and erosion. According to the U.S. Department of Agriculture, the 43 percent decrease in soil erosion on U.S. croplands between 1982 and 2003 was largely due to the increased use of conservation tillage [source: Huggins and Reganold].

On conventional farms, where the loose top layer of s­oil lacks the structure of organic matter to hold it together, wind and rain have an easy time washing it away -- transforming what should be a valuable farming input into a pollutant that affects nearby water sources along with any added fertilizers and pesticides. In untilled soil, the residue left on the surface serves as a sort of protective barrier from erosive elements. When it rains, this mulch cover softens the impact of the raindrops. Since it also keeps the ground underneath from drying out, it enables the soil to more readily absorb that rain, thereby significantly reducing erosion and runoff.

Fewer trips across the farm with a plow also lead to less soil compaction. One contingency that appreciates that extra breathing room is the earthworms: Within a few years of converting to no-till, earthworm numbers can be up to eight times as much as those on tilled farms [source: Fawcett and Caruana]. The result of all those extra burrows is an increased surface area of nooks and crannies for the rain to go. During 12 rainfall events on a tilled farm, water flow into earthworm holes accounted for 1.2 to 10.3 percent of the rainfall [source: Fawcett and Caruana]. This improves water infiltration even more, enabling crops to hold onto moisture and thrive even in times of reduced rainfall when tilled fields are suffering.

­With all the benefits that no-till farming offers, one wonders why it's been so slow to catch on. No-till farming may be just what the doctor ordered, but it isn't always an easy pill to swallow.

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­There's no doubt that no-till farming brings many rewards, but those rewards aren't always immediately apparent. In the first few years of transitioning to a no-till system, many farmers experience increased weeds and pests, lower productivity and other problems.

Indeed, one of the key challenges of no-till farming is that it often requires more herbicides to keep weeds and pests at bay. Without the benefit of the plow to churn those pesky weeds down into the earth, many previously unseen visitors may make an appearance. In addition, the transition's impact on soil composition can cause new species of pest to appear. The increased soil moisture accompanied by no tilling may also promote soil borne fungal diseases.

Some farmers also experience initial declines in productivity. Because crop residues block the warmth of the sun's rays, untilled soils are considerably cooler, which can lead to delayed planting and slow germination of warm-season crops. In addition, certain soils aren't as forgiving when it comes to altering your farming methods. Fine-textured soils with poor drainage may see declines of 5 to 10 percent when no-till production is applied [source: Huggins and Reganold].

Yet another challenge some farmers face is the expense of no-till machinery. Specialized planters that slice into the soil and deposit seeds aren't always cheap, and sophisticated designs can cost more than $100,000 [source: Maag]. However, that extra cost could potentially be offset by the elimination of other equipment that's no longer necessary -- by ditching pieces of older tillage equipment, farmers may significantly lower their total capital and operating costs.

­Finally, no-till often requires the use of extra fertilizers in the first few years of adoption since increased organic matter at the soil surface immobilizes nutrients. Along with the increased need for herbicides, this heavy reliance on agrichemicals can be off-putting to many purists.

­Despite its drawbacks, no-till may yet redeem itself. Among other things, the reduction in passes across the field with heavy tilling machinery amounts to 50 to 80 percent less fuel usage and 30 to 50 percent less labor [source: Huggins and Reganold]. There are also ways to get around the heavy application of chemicals. Read about some of the ways seasoned farmers are increasing yields with alternative methods on the next page.

­While initial hang-ups may be unavoidable when making the transition to no-till, experienced practitioners have found ways to skirt the more persistent problems.

Crop rotation is one of the more effective weapons in their agricultural toolbox. This practice, which isn't unique to no-till farmers, is a good way to keep pests under control. Instead of growing a monoculture, or repeatedly planting the same crop in a field year after year, crop rotation involves planting different crops in that field. By alternating the types of plants in the soil, crop rotation works to confuse the resident pests, leaving them without the chance to establish themselves and do any real damage.

Other beneficial no-till tools include the planting of cover crops. Instead of leaving a field empty and exposed when it's not in production, farmers plant something else to cover and protect the soil. Depending on the crop chosen, these cover crops may also enrich the soil with nutrients or help to break it up with their roots. Common cover crops, which may or may not be harvested, include soybeans and millet in the summer and field peas and cereal grains in the winter.

With the right combination of crop rotation and cover crops, many farmers have found a way to get around the need to apply quite so many chemicals. Crop rotation becomes the "pesticide" and cover crops, the "fertilizer."

­While the area of land under no-tillage globally remains small, it has grown significantly during the last century. In the United States -- the country with the largest area of no-tilled land -- the farming method has grown from being practiced on 5.4 million acres (2.2 million hectares) in 1973 to 11.9 million acres (4.8 million hectares) in 1983 to 62.5 million acres (25.3 million hectares) in 2005 [source: Derpsch].

While those numbers are impressive, 62.5 million acres (25.3 million hectares) only amounts to about 17 percent of U.S. arable land. The country with the largest percentage of its land managed as no-tillage is Paraguay, with 65 percent. Brazil and Argentina are not far behind with 60 percent [source: ­Derpsch].

Conservationists applaud the high adoption rates of no-till farming in the Americas, calling it an effective tool for halting soil erosion and making agriculture truly sustainable. They're hopeful that the rest of the world will soon follow.

Africa, with its high rate of soil erosion, has great potential for conservation agriculture, as does Asia, where erosion is a problem, as well as the lack of farm machinery. No-till farming would be a way to kill two birds with one stone.

In the places where it has been successful, conservation agriculturists and local farmers' organizations play an important role, providing support and advice for what can be a difficult setup process. For best results, experts advise that farmers making the switch only convert 10 to 15 percent of their farm to no-till at one time: Sustainability is, after all, a long-term process [source: Huggins and Reganold].

For more information about no-till farming and conservation agriculture, plow on through to the next page.