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Breakdown: Why no-till farming is so common in the Mid-South

Published: Oct. 22, 2021 at 1:33 PM CDT
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MEMPHIS, Tenn. (WMC) - Like clean water and fresh air, good, farmable soil is vital to our continued survival - and we’re destroying it in mass quantities.

According to geologist David Montgomery, author of Dirt: The Erosion of Civilizations, the world loses roughly 23 billion tons of good soil each year. At that rate, all fertile soil will be gone within 150 years, unless farmers convert to practices that restore and build soil organic matter, an essential component of soil fertility.

Fortunately, Tennessee farmers have been transforming the landscape for decades with no-till farming methods, helping to restore the state’s soils. Today, Tennessee is a shining example of the no-till success, with up to 90% of the state’s farms using no-till practices, according to the USDA National Agricultural Statistics Service.

This change was possible thanks to the assistance and innovation of the University of Tennessee’s Research and Education Center at Milan, who has been a leader in this effort since 1981. The research conducted by UT AgResearch at Milan is known worldwide.

The Milan AgResearch and Education Center is considered a leader in the no-till technology movement. Each year our research saves millions of tons of Tennessee soil from erosion. Soil erosion is not only devastating to farms, but it also pollutes our water, damaging wildlife habitats and contaminating our drinking water supply. Through research, we combat soil erosion by continually improving no-till’s ecological benefits.

https://milan.tennessee.edu/our-research/

No-till started because West Tennessee was losing so much topsoil. UT Ag Institute experts now say no-till saves millions of tons of soil each year, and leads to higher yields and lower costs for producers.

Before no-tilling practices began in West Tennessee, it was ranked as one of the top areas in the U.S. for the highest soil erosion rate with 40 tons of soil per acre per year lost.

Some soils across the entire state of Tennessee are considered fragile, but west Tennessee’s are especially susceptible and erodible because they are very silting soils. This means are they moved very easily by water if they are tilled and exposed.

Unlike tillage, commonly known as plowing, no-till methods leave soils undisturbed, allowing crop residue to remain on the surface, protecting the topsoil from runoff. Seeds are planted in rows in the soil. In contrast, tillage leaves soil “bare” and highly susceptible to erosion.

No Till Vs Conventional Tillage
No Till Vs Conventional Tillage(nrcs.usda.gov)

Tilling involves turning over the first 6 – 10 inches of soil before planting new crops. This practice works surface crop residues, animal manure and weeds deep into the field, blending it into the soil. It also aerates and warms the soil. Sounds like a good thing, right? Unfortunately, in the long run, tilling does more harm than good. Here’s why:

Tillage loosens and removes any plant matter covering the soil, leaving it bare. Bare soil, especially soil that is deficient in rich organic matter, is more likely to be eroded by wind and water. Think of it this way: Undisturbed soil resembles a sponge, held together by an intricate structure of different soil particles and channels created by roots and soil organisms. When the soil is disturbed by tilling, its structure becomes less able to absorb and infiltrate water and nutrients.

Tilling also displaces and/or kills off the millions of microbes and insects that form healthy soil biology. The long-term use of deep tillage can convert healthy soil into a lifeless growing medium dependent on chemical inputs for productivity.

From a soil perspective, the benefits of no-till farming far outnumber those of tillage-based systems. No-till practices allow the soil structure to stay intact and also protect the soil by leaving crop residue on the soil surface. Improved soil structure and soil cover increase the soil’s ability to absorb and infiltrate water, which in turn reduces soil erosion and runoff and prevents pollution from entering nearby water sources.

No-till practices also slow evaporation, which not only means better absorption of rainwater, but it also increases irrigation efficiency, ultimately leading to higher yields, especially during hot and dry weather.

Soil microorganisms, fungi and bacteria, critical to soil health, also benefit from no-till practices. When soil is left undisturbed, beneficial soil organisms can establish their communities and feed off of the soil’s organic matter. A healthy soil biome is important for nutrient cycling and suppressing plant diseases. As soil organic matter improves, so does the soil’s internal structure—increasing the soil’s capacity to grow more nutrient-dense crops.

It’s clear that adopting no-till practices is good for the soil. But it also benefits the farmer because conventional tillage practices require the farmer to make several passes over the field, first tilling the soil and then returning to plant seeds. No-till removes the step of tilling the soil and therefore saves the farmer time and money and fuel.

According to the U.S. Department of Agriculture:

On average, farmers practicing continuous conventional till use just over six gallons of diesel fuel per acre each year. Continuous no-till requires less than two gallons per acre. Across the country, that difference leads to nearly 282 million gallons of diesel fuel saved annually by farmers who practice continuous no-till instead of continuous conventional till.

Farmers who manage at least one crop in their rotation without tilling – seasonal no-till – save an additional 306 million gallons of fuel annually.

https://www.usda.gov/media/blog/2017/11/30/saving-money-time-and-soil-economics-no-till-farming
Farmers across the country save fuel and money by adopting conservation tillage practices.
Farmers across the country save fuel and money by adopting conservation tillage practices.(Natural Resources Conservation Service / USDA)

According to a report published in Scientific America, this decreases the fuel expense by 50 to 80 percent and the labor by 30 to 50 percent.

The Natural Resources Conservation Service has more information about ways to mimic nature and the benefits of healthy soil here.

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