Biologist here, I see these trees all the time! I can only really comment on the southern Great Plains (KS, CO, TX, OK, NM). The northern states used a mix heavy with exotic/invasive Siberian Elms which differs from what I see down south. My post is anecdotal observations based on ~15 years in the area, but I’m also incorporating first hand accounts from farmers and other professionals.

“HOW SUCCESSFUL WAS THIS INITIATIVE?” Combined with other practices (CRP and contour plowing), it was successful. Windbreaks definitely help to slow soil erosion from wind, but the most helpful practice is simply not plowing all the land. The Conservation Reserve Program (CRP) is a USDA program funded by the Farm Bill that pays landowners to maintain grasslands on poor/marginal farmland. This is a response to the early 20th century practice of farming every acre possible, which in turn created the Dust Bowl. The Great Plains were originally native prairie grasses which have very long root systems that stabilize soil. When it was all broke up by the plow, the soil had nothing to hold it into place. Every state did their CRP a little different based on what seeds they had locally available. KS planted native tall grasses, OK planted exotic Old World bluestem, etc. So, the CRP worked, although over the years the overall funding for the CRP keeps decreasing the per acre rate in each county, leading to many of these CRP fields being “broken up” and plowed into farmland. If you see a circular crop field with center pivot irrigation, but the field also has these grass “corners”, it is likely a CRP field that’s been converted back to crop land (an exception would be the “Corners for Conservation” program by Pheasants Forever).

“WHERE ARE THOSE TREES TODAY?” Here is a great StoryMap on the history and locations of windbreaks: https://www.arcgis.com/apps/MapSeries/index.html?appid=ceb1a9f56acb480a944b9fada7ec258e

Most of the tree rows I see are hedge apple aka Osage Orange aka many other common names. As with grasses used in the CRP, the trees used for windbreaks varied by locality based on suitability and availability. The tree windbreaks are typically along county roads, aka section roads, that are laid out on a 1 mile grid. Many sections (640 ac / 1 sq mile) are often broken up into 4 fields, aka “quarters”, and there’s often a tree windbreak between the quarters. Often, windbreaks also occur along farmer’s homes. Less often, there are breaks within the field itself.

Some farmers remove these trees to get an extra 2 to 10 acres per field along the edges, basically making fields bordered by permanent vegetation into “ditch-to-ditch” farming, that is, the field is 100% plowed monoculture crop land from one county road ditch to the next country road ditch a mile away. Removing the edge doesn’t actually improve productivity; precision agriculture studies regularly show that the outer 30-60 ft edge of fields is less productive and typically not profitable to plow. However, if there is a vegetation buffer of grass/trees, the negative edge effects on the crop are absent. The basis behind this rationale is to prevent weed encroachment. I don’t know if the financial damages from weed encroachment exceed the losses in productivity on the edges with ditch-to-ditch farming. Spraying herbicides is expensive, so all of this weighing input costs vs output gains, which can vary by field.

Another positive side effect of these windbreaks is that they provide travel corridors, thermal protection in the cold, and escape cover from predators for wildlife.

This next paragraph gets a bit more into subjective concepts like psychology. Abrahamic traditions are the underlying bedrock of American farm/ranch management. I don’t want to be speculative, but my perception is that many landowners want to have “clean” fields due to pride and their perception by others in the community. I’ve gleaned that perception based on dozens/hundreds of comments I’ve had with landowners. I regularly observe land management practices that occur in regional “bubbles” that differ from the broader norms and have no financial advantage. An example: during the 2010s oil boom, many of the farmers in an area the size of about half a county used part of their newly increased income to hire dozers to destroy windbreaks, resulting in ditch-to-ditch monoculture crop land. I’ve spoken to many of them, and the reasons they did this were not consistent. I interpret it as exerting mastery over the land.

Aldo Leopold put it best: “Conservation is getting nowhere because it is incompatible with our Abrahamic concept of land. We abuse land because we regard it as a commodity belonging to us. When we see land as a community to which we belong, we may begin to use it with love and respect.”

To summarize, windbreaks worked, many are still around, but we are repeating old mistakes and making some new ones.

I’ll just leave this here:

https://kdvr.com/news/local/100-mph-winds-blow-dust-from-colorado-into-kansas-texas-and-oklahoma/