The Myth of Depleted Soils--Is It True?

How many times have you heard about how non-nutritious our fruits and vegetables are these days because of over-farming? According to the “depleted soils” myth, our croplands have been so damaged by years and years of mainstream farming that our foods are no longer nutritious enough to sustain us. They contain, some people claim, only a fraction of the vitamins and minerals the same fruits and vegetables contained 50 years ago.

And worst of all, these depletions are causing everything from worsened menopause symptoms to cancers that are striking younger and younger folks. It sounds scary but, as we’ll show you, it’s not true. Consider these facts about the “depleted soils” myth:

• While it’s true that minerals can be depleted by over-farming, there’s absolutely no truth that crops deplete the soil of vitamins. Why? Because there are no vitamins in dirt in the first place. Growing plants don’t absorb vitamins from soil—they make their own vitamins as they grow.
• Common sense would tell you that depleted soils simply wouldn’t allow plants to produce fruits and vegetables in sizable numbers but our ability to grow more food crops per acre of land has leapfrogged in the past 40 years. In 1950, for example, the average acre of corn produced a little over 37 bushels of corn per acre; in 1992 that number had risen to nearly 129 bushels per acre.
• Many crop farms practice an ancient farming technique known as “rotation farming”. In rotation farming heavy-feeder crops are planted and harvested then the land is either allowed to sit for a time or is planted with crops that are specifically chosen to return nutrients to the soil.
• Finally, as experts from the University of Wisconsin point out in their piece titled “Are Depleted Soils Causing a Reduction in the Mineral Content Of Food Crops?” farmers not only routinely test for things like mineral content; they also fertilize their fields regularly. How can a plot of land that’s being regularly supplemented with minerals be mineral deficient?

So why does the “depleted soil” myth persist? Well, there has been some data suggesting that mineral contents are declining in some of the world’s farmlands. But that data is controversial and some experts believe it’s been taken out of context by people pushing their own political or environmental agendas.

So is there really any truth to the myth about depleted soils causing low-quality foods? Well, after looking at the facts, what do YOU think?

Sources:

Lyne, J., Barak, P. (2000). Are Depleted Soils Causing a Reduction in the Mineral Content Of Food Crops? Accessible at soils.wisc.edu.

Tisdale, S., et al. (1992). Soil fertility and fertilizers; an introduction to nutrient management. Prentice Hall.

Rothman, M. (2002). Menopause: Myths vs. Facts. Accessed from fwhc.org May 26, 2010. (Claims depleted soils are worsening menopause.)

Cawood, M. (2009). Why depleted soils are making us sick. Accessed from theland.farmonline.com.au on May 26, 2010. (Claims depleted soils are increasing breast cancer in younger women.)

Comments

[Bruce]

Sorry, but I have to disagree with the thrust of your article. Firstly, I'm not aware of anyone claiming that vitamins are in the soil- that would be absurd. So that's a bit of a red herring. Secondly, while rotating crops does prevent some of the reduction of soil fertility seen in monoculture, the lion's share of our food come from large agribusinesses which use monoculture. The minerals are stripped from the soil and although *some* is replaced through fertilizer they are mainly concerned with minerals which promote growing biomass- not nutritious food. The soil is virtually lifeless, fewer helpful microorganisms, fungi and earthworms are found there.

Garbage in > garbage out.

Here is a quote followed by a link to an article which shows how the nutrient value of our produce has declined over the years:

"..the average vegetable found in today’s supermarket is anywhere from 5% to 40% lower in minerals than those harvested just 50 years ago. His research finds that recently grown crops have shown decreases of up to 38% in protein, magnesium, calcium, vitamin C, phosphorus, iron, zinc and riboflavin when compared with produce from past decades."

[Lisa Barger]

Readers, Bruce is referring to a 2004 study done by Donald Davis that appeared in an issue of the Journal of the American College of Nutrition. BUT Davis and the other scientists behind that research don't "credit" worsening soil with the declines--they blame changing genetics in those foods. To quote Davis himself:

“We conclude that the most likely explanation was changes in cultivated varieties used today compared to 50 years ago."

He goes on to say," . . . when you select for yield, crops grow bigger and faster, but they don’t necessarily have the ability to make or uptake nutrients at the same, faster rate.”

You can read Davis' comments about his research--in context-- here.

[Joyce]

Oh the vitamins/soil myth is alive and well, I assure you. It took me 5 seconds to find it on the first page of a Google search: http://www.coralcalciumnow.net/SeaVegg.html

[gerovital romania]

well whether or not the human body adapts to many situations and substances

[Lisa Barger]

I've asked the Site Admin to close the comments on this article due to spam and supplement hawkers coming here only to argue based on something they read "somewhere".

All I ask of my readers is to look at all the evidence and then look at the credibility of those sources. Ours was a university study done by experts with years of experience in the field and no lemme'-sell-you-something agenda.

At the end of the day, it doesn't really matter what I think or what some vitamin seller thinks. It's YOUR choice. All I ask is that you make an informed one.