I must admit this is very confusing: one gets different types of information from different sources that often contradict one another.

It is said that the main event occurred due to some misguided farming practices; that those practices allowed strong winds to pick up all the topsoil in the area, carry it east, and deposit it into the Atlantic, more or less in toto. This may not be altogether accurate, but that's the impression one gets from reading essays, articles, and the Wikipedia entry pertaining to the Dust Bowl.

That said, various sources maintain that it takes 500 years or more to form 1 inch of topsoil.

Others suggest coyly that the process can be expedited artificially by burying lots of organic garbage and introducing earthworms to it: a few years of this, and voila - we've got topsoil! (Few of them say how many years, exactly, and where's one supposed to get all those earthworms?)

Still other sources say that because of soil erosion and other intriguing factors we may be running out of arable land. And not just in Kansas either, but all over the globe.

With all of the above in mind, my question is: have the areas affected by the Dust Bowl recovered partially, completely, or not at all? How much of that land can be classified as arable once again?

  • $\begingroup$ Good question, but arable is hard to define. Maybe you find stats for the Soil-Adjusted Vegetation Index or similar indices used in agronomy over time for the affected areas. Don't know enough about agronomy etc. to help here much + it's uncertain that the data is even there. $\endgroup$ – mart Dec 16 '15 at 13:32

Soil is not a single uniform material. When wind erosion takes hold, as in the infamous 'dust bowl' of the 1930s, it is the uppermost A horizon, and to a lesser extent the B horizon that is mainly lost. The lost soil takes with it most of the organic carbon, and it is this component that is most difficult to replace.

Rates of soil loss are primarily factors of the underlying geology and climate. A wetter and warm climate will regenerate soil very much faster than a cold dry climate. Basalt and shale will break down into soil much faster than, for example, quartzite or granite. The rate of rock weathering is not quite the same as the rate of soil formation.

As a first approximation, rate of weathering = rate of soil formation + rate of mass loss by various processes.
Wakatsuki and Rasyudin (1992) Rates of Weathering and Soil Formation, Geoderma, V52, 3-4, gives a good assessment of such rates.
Their best estimate is that soil formation occurs at 370–1290 (mean = 700) kg ha−1 yr−1. Or roughly 0.3 mm per decade, excluding the lost organic carbon. This is equivalent to about 3 mm of new soil generation since the great dust bowl.

In other words, no, the lost soil is nowhere near replenished yet. Moreover, the impact of climate change does not bode well for the future of soil regeneration.

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  • $\begingroup$ Very good and informative, but not quite what I asked. $\endgroup$ – Ricky Dec 11 '15 at 7:57

Your first question is relatively simple.

We can rule out complete recovery (virtually impossible in such a short time span), which leaves two choices: partial recovery or no recovery at all. There has certainly been some partial recovery. However, given the uneven farming practices and land protection that characterize agriculture in the U.S., it seems logical that some of the land has recovered very little, if any.

Below are some interesting quotes:

Although it achieved less than it might have, the New Deal did much to hasten recovery in the Dust Bowl; more importantly, the rains began anew. As the buffalo grass spread again, the bowl area rapidly shrank from 8.727 million acres in 1938 to 1.2 million in 1939. Yet there remained the danger that farmers would forget the terrible lessons from the drought and that the Dust Bowl would once again reappear. (Dust Bowl)

While some of the Dust Bowl land never recovered, the settled communities becoming ghost towns, many of the once-affected areas have become major food producers. (The Dust Bowl Revisited: 2012)

The 1930s American Dust Bowl was an environmental catastrophe that greatly eroded sections of the Plains. The Dust Bowl is estimated to have immediately, substantially, and persistently reduced agricultural land values and revenues in more-eroded counties relative to less-eroded counties. During the Depression and through at least the 1950s, there was limited relative adjustment of farmland away from activities that became relatively less productive in more-eroded areas. Agricultural adjustments recovered less than 25 percent of the initial difference in agricultural costs for more-eroded counties. The economy adjusted predominantly through large relative population declines in more-eroded counties, both during the 1930s and through the 1950s. (The Enduring Impact of the American Dust Bowl)

I don't know the answer to your second question - How much of that land can be classified as arable once again?

How does one define arable - capable of producing the same bountiful crops that were produced before the Dust Bowl or barely capable of producing crops? Capable of producing wheat and corn or capable of producing genetically modified soybeans nurtured by Roundup?

If anyone has produced some general figures on the current acreage in the multi-state area that's officially classified as "arable" (or simply the acreage that's currently being farmed), that would be interesting. The information might be acquired by contacting agricultural agencies in various states.

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