Overplowing is one of the less talked about causes of topsoil loss and desertification. While overplowing has been a potential problem since plows were first invented, it has only been a major, worldwide problem for the last few decades, as large-scale farming becomes more and more common.

One of the earliest and best-known cases of overplowing occurred in the central North American plains in the 1930s. Settlers moved into new, fertile lands, and started farming thousands of acres. Unfortunately, the Great Plains were experiencing an unusually wet period. During the 1880s through the 1920s weather was largely favorable, and farms did very well. But in 1930 an extended drought caused the ground to dry out, and poor farming practices encouraged the topsoil to blow away in the wind. Giant dust storms blew Eastwards across the continent, and millions of people had to abandon their homes as their livelihood blew away in the wind. The affected areas and the storms that plagued them became known as the Dust Bowl.

Overgrazing and overplowing removed the natural prairie grasses, and farmers burned or plowed out the stems and other crop remains that might have helped control erosion. The continuous re-tilling of the soil, with no fields left fallow to regrow grasses, kept the soil raw and ready to blow away. Even if the land had been barren, plowing up the topsoil only encouraged it to blow away faster.

It can be hard to untangle the effects of overplowing from overcultivation and overgrazing. Overcultivation depletes the soil of nutrients, and decreases plant growth of all sorts. This can turn fertile earth into a desert even without overplowing. Overgrazing cuts out a step, removing all plants and killing seedlings before they can grow, allowing soil to blow away with much of its nutrients intact. Overplowing can include the effects of continuously plowing and replanting fields without allowing them to lie fallow, the breaking up of the earth in such a way as to make them prone to erosion (wind or water), and intensive tillage methods that remove crop residue from the fields.

Fallow Fields: Aside from giving the soil a chance to recharge its nutrients, letting a field lie fallow gives the land a safety net. Having a fraction of your land covered with a native grass means that you have one field filled with plants that will survive most weather patterns. Even if you have a dry year, if it is at all within the range of what has been usual for the past few hundred years, local scrub and grasses are likely to survive. These plants can also be used as a grazing crop, keeping the fields productive even during the fallow periods.

Erosion: While wind is the usual culprit, carrying off hundreds of tons of topsoil during drought years, on a smaller scale water erosion can be a problem too. The 'modern' method of plowing fields in long rows allows water to run across fields and carry off the dirt. In many third world countries people still use hoes to dig up small mounds, closely dotted across the landscape. This is an excellent, although rather labor intensive, way of planting crops in places where erosion is likely to be a problem, either on steep hillsides or in places where there are extreme rainy seasons. Long furrows plowed into a hillside can be a recipe for disaster, particularly if they run down the hillside rather than across.

Crop residue: Leaving bits and pieces of plants in the soil can help prevent both wind and water erosion, although its primary benefit is in preventing water erosion. (It also keeps the soil from compacting too much, warms the soil, and saves the farmer fuel and time; although there are downsides as well). The tillage will help the earth absorb water, preventing water from collecting on the surface and forming rills, which carry off dirt. A field with a high percentage of crop residue cover can look more like a compost pile than a dirtscape, and will also help keep the dirt wet longer; both covering the soil and keeping the soil damp will help prevent wind erosion.

Brute force: No matter how careful you are, when you are plowing dry earth you will leave a window during which winds can produce dust. If you are plowing millions of acres, you will produce a lot of dust. As farming continues to move into more marginal areas, and as more and more land is farmed, more and more dust goes up into the air. This can be a significant source of dust even in the absence of unusual droughts or winds. No-till farming can help avoid these problems.

China is currently having problems that parallel the American Dust Bowl. Giant clouds of dust are blowing off of its fields and being carried into cities, darkening the skies, grounding airplanes, and becoming a health issue as people breathe in the particles. These dust clouds are big enough to be a serious problem in neighboring countries like North Korea, South Korea, and Japan. They have also been blowing across the Pacific and have reached America. This represents a tremendous loss of soil that China cannot afford to lose, and is obviously not a good thing for those that the dust clouds reach. Thousands of kilometers are turning to desert each year, and China cannot afford to cut back on its farming. China has been planting trees and continuing its attempts to keep population down, both of which are important measures. There are other things that might be done; Lester R. Brown has suggested placing wind farms as windbreaks.

China is the current prime example of overplowing, but as the world population continues to grow and food needs perhaps grow even faster, there are likely to be many more examples of massive erosion due to overplowing. There already are massive problems caused by overgrazing, overfishing, overcultivation, and deforestation. The good news is that we are smarter than we have ever been, and lots of smart people are working on these problems.

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