its an interesting question; there is little doubt that farmers had been having trouble with blowing and drifting sand for decades before the 1930s, (the term "soil drifting" was used as early as 1892) . . . There are also multiple sources that demonstrate that attempts to prevent soil loss were being tested prior to the 20th century; many government farms, and workers in Canada and in the US spent a lot of time trying to prevent soil damage. Prior to the 20th century there were already shelter belts, the use of legumes, crop rotations, etc.

The reality is that in the 1900s soil blowing was a serious problem (40 percent of Saskatchewan farmers complained about soil blowing by 1919) and there were sections of land that were no longer workable due to over use of land on under watered regions.

Did they know it would turn into the Dust Bowl?

Well, it was well known that the "there was no type of farming more damaging to the land than wheat farming" very early on (1890s) and multiple failed attempts to convince farmers to adopt diversified farming, or crop rotation, or plant shelter belts. There had been already serious dust storms in Saskatchewan, and some further south; one of the biggest problems is the DFC, the Dry Farming Congress which was economically incentivized to load the farmers up with equipment they did not need and which contributed to the destruction of the land.

So, yeah, I would have to say that if a person had asked the soil scientists at the University of Saskatchewan or the Department of Ag in US or Ottawa to predict what would happen with a few years of below average rainfall, and it is pretty easy to conclude they would have said yes.

And, keep in mind that there were many years in the 30s that had normal or near normal rainfall, though my data is lost somewhere and it would take time to find it. Trust me :-) Just destroyed land, by then--thirty to forty years of blowing and drifting.-- The 30s were not an event, but the last part of an event.

Sources: My dissertation, which is an environmental study of the causes of the Dirty Thirties in SK-- since this post is a month old, I seriously doubt I will be asked for more cites, but if necessary I believe I had 988 footnotes in my dissertation total. I bet I will find a few easy ones. Mary Heargraves for example, regarding the DFC.

I believe that the Dust Bowl storms were caused by literal dust. Farmers had overworked the soil with bad agriculture practices for decades before. This was followed by years of intense drought.

It was clear that the dust storms were becoming more common. The first year of the dust storms only saw 14. The next 36. This continued until the storms became larger and more life threatening.

I dont think it's fair to assume they knew how violent the storms would become.

However, April brought the most violent dust storm, called "Black Sunday". Congress passed a law 2 weeks later creating the soil conservation district and declared "soil erosion a national menace."

Overall, I think average people understood that the dust storms were caused by the drought, and the subsequent dusty soil. I don't believe they understood soil erosion and the role it played in the dust storms.

Source:http://www.english.illinois.edu/maps/depression/dustbowl.htm