Key to Survival: Healthy Soil
As my first-grade teacher Miss Garner used to say, "Let's pretend for a minute."
Let's pretend that you've just welcomed a new grandbaby to your family. Your little darling has joined the ranks of the approximately 6.6 billion people currently on this earth. Now let's fast-forward to that baby's retirement years — say, age 68 — when he or she might be enjoying their new grandchild.
By that time, the latest little twig on your family tree will be joining a world population of, according to United Nations projections, 9.22 billion. You're not misreading those numbers; from the recent arrival of your brand-new grandbaby until the arrival time of his or her new grandbaby, the world population is expected to grow by a staggering 39.69 percent.
There are many factors that will impact on how — and whether — all those billions of folks have something to eat and something to wear, but the three most basic factors have never changed: soil, water and air. And it's more than just a matter of having soil and water to grow crops; the quality of that soil and water is crucial.
That's why the scientists of the Agricultural Research Service (ARS) have been putting a lot of thought and effort into long-term studies of soil health: what benefits the soil, what works best, and how long those improvements take.
The results may surprise you (I suspect that they even surprised the scientists). For example, would you have anticipated that organic farming could do more than no-till farming to build up soil organic matter? ("No-till" is exactly what it sounds like; instead of plowing the fields clean and then planting crops, farmers plant their new crops directly into the residue of the previous crops, thus avoiding exposing the bare soil to erosion by rain and wind.)
From 1994 to 2002, the ARS scientists compared minimal-tillage organic corn, soybeans and wheat with the same crops grown conventionally with no-till. The conventional wisdom has always been that you get bigger boosts in levels of soil organic matter from no-till farming than from organic farming. That's because organic farming uses tillage — to work manure into the soil and control weeds. And after all, tillage is known to destroy soil organic matter.
But the ARS study study showed that organic farming increased levels of soil organic matter better than conventional no-till, because the use of manure and cover crops more than offset the losses from the tillage.
Just to be sure, the ARS scientists followed the nine-year study with a three-year study in which they grew corn with conventional no-till practices on all of their plots to see which ones had the most productive soils. The results? The organic plots had more carbon and nitrogen and yielded 18 percent more corn than the other plots.
This is a classic case of patience being a virtue; the scientists say it takes so much time to build up organic matter that they wouldn't have seen these results if they hadn't had such a long-term study.
Other surprises came to ARS scientists who stayed in it for the long haul. For example, in the wheat-growing regions of the Pacific Northwest, rainfall can be as little as 11 inches a year. But ARS and Washington State University scientists look a long view — eight years — at what happens when it's even dryer than usual in wheat country.
In that study, the scientists found that when farmers get their "normal" amount of rain, scant though it may be, the economic returns from growing no-till spring wheat every year are about the same as growing winter wheat only every other year and letting the ground lie fallow for a year to save up moisture for the next crop.
But in drier years, annual cropping makes less economic sense. In fact, the eight-year average net returns for annual cropping lag behind that conventional scenario of the summer fallow rotation by as much as $29 per acre.
As you can see from the length of these studies, sometimes the answers are a long time coming. But I'm glad that the scientists at ARS are listening for those answers now, or else it could be a lot harder to feed your grandbaby's grandbaby in 2075 when Mother Earth is having to support those 9.22 billion people.
"Everybody's
Science" is written by Sandy Miller Hays, Director of Information for
the Agricultural Research Service, the chief scientific research agency
of the U.S. Department of Agriculture. Hays is a native of Fort Smith,
Ark. From the late 1970s until early 1988, Hays was a reporter, editor
and columnist at the Arkansas Democrat (now the Arkansas Democrat-Gazette),
a Little Rock-based daily newspaper. She joined the ARS Information
Staff in 1988, and became Director of Information in April 1998.
As my first-grade teacher Miss Garner used to say, "Let's pretend for a minute."
Let's pretend that you've just welcomed a new grandbaby to your family. Your little darling has joined the ranks of the approximately 6.6 billion people currently on this earth. Now let's fast-forward to that baby's retirement years — say, age 68 — when he or she might be enjoying their new grandchild.
By that time, the latest little twig on your family tree will be joining a world population of, according to United Nations projections, 9.22 billion. You're not misreading those numbers; from the recent arrival of your brand-new grandbaby until the arrival time of his or her new grandbaby, the world population is expected to grow by a staggering 39.69 percent.
Plant physiologist John Teasdale records data on weeds growing in a ripening organic wheat field next to a recently cultivated plot of organic corn. (Photo by Charles Phillips)
That's why the scientists of the Agricultural Research Service (ARS) have been putting a lot of thought and effort into long-term studies of soil health: what benefits the soil, what works best, and how long those improvements take.
The results may surprise you (I suspect that they even surprised the scientists). For example, would you have anticipated that organic farming could do more than no-till farming to build up soil organic matter? ("No-till" is exactly what it sounds like; instead of plowing the fields clean and then planting crops, farmers plant their new crops directly into the residue of the previous crops, thus avoiding exposing the bare soil to erosion by rain and wind.)
From 1994 to 2002, the ARS scientists compared minimal-tillage organic corn, soybeans and wheat with the same crops grown conventionally with no-till. The conventional wisdom has always been that you get bigger boosts in levels of soil organic matter from no-till farming than from organic farming. That's because organic farming uses tillage — to work manure into the soil and control weeds. And after all, tillage is known to destroy soil organic matter.
But the ARS study study showed that organic farming increased levels of soil organic matter better than conventional no-till, because the use of manure and cover crops more than offset the losses from the tillage.
Just to be sure, the ARS scientists followed the nine-year study with a three-year study in which they grew corn with conventional no-till practices on all of their plots to see which ones had the most productive soils. The results? The organic plots had more carbon and nitrogen and yielded 18 percent more corn than the other plots.
This is a classic case of patience being a virtue; the scientists say it takes so much time to build up organic matter that they wouldn't have seen these results if they hadn't had such a long-term study.
Other surprises came to ARS scientists who stayed in it for the long haul. For example, in the wheat-growing regions of the Pacific Northwest, rainfall can be as little as 11 inches a year. But ARS and Washington State University scientists look a long view — eight years — at what happens when it's even dryer than usual in wheat country.
In that study, the scientists found that when farmers get their "normal" amount of rain, scant though it may be, the economic returns from growing no-till spring wheat every year are about the same as growing winter wheat only every other year and letting the ground lie fallow for a year to save up moisture for the next crop.
But in drier years, annual cropping makes less economic sense. In fact, the eight-year average net returns for annual cropping lag behind that conventional scenario of the summer fallow rotation by as much as $29 per acre.
As you can see from the length of these studies, sometimes the answers are a long time coming. But I'm glad that the scientists at ARS are listening for those answers now, or else it could be a lot harder to feed your grandbaby's grandbaby in 2075 when Mother Earth is having to support those 9.22 billion people.
The Agricultural Research Service is the chief in-house scientific
research agency of the U.S. Department of Agriculture. You can read
more about ARS discoveries at http://www.ars.usda.gov/news/.
About the author
"Everybody's
Science" is written by Sandy Miller Hays, Director of Information for
the Agricultural Research Service, the chief scientific research agency
of the U.S. Department of Agriculture. Hays is a native of Fort Smith,
Ark. From the late 1970s until early 1988, Hays was a reporter, editor
and columnist at the Arkansas Democrat (now the Arkansas Democrat-Gazette),
a Little Rock-based daily newspaper. She joined the ARS Information
Staff in 1988, and became Director of Information in April 1998.