13.2.9: Agricultural Regions

Agricultural Regions

As is the case with BBQ, numerous geographic variables inform the choices farmers make about what to do with their land. The first factor is climate. Weather is a controlling factor in most agricultural decisions. Many crops and some livestock just can’t survive in harsh climates. Some crops are exceptionally hardy, and some even require harsh weather conditions to thrive. The availability of water, either via rain or irrigation is another fundamental issue for farmers. Most farmers also need to turn a profit; and the clear majority prefer to maximize their profits, so farmers carefully choose the crops and animals they raise. Farmer decisions, in turn, affect what we eat, just as what we eat affects what they plant. Taken together, these decisions have created roughly five major agricultural zones in the US, each aligned with a climate zone. The paragraphs below explore the evolution and function of some of the major agricultural regions in the US, and elsewhere

Corn and Wheat Belts

The two largest agricultural regions in the United States are roughly split by the 100th meridian, a line of longitude that marks a transition zone between the humid eastern half of the US and the drier western half. The 100th meridian runs straight through the middle of the US, where the land is flat and ideal for row cropping. Farmers east of the 100th meridian generally plant corn (maize) and soybeans, and therefore this region is called the Corn Belt. It’s roughly centered on Iowa, “The Tall Corn State”. Much of this land now used to grow corn was once tallgrass prairie before it was plowed under and made into cropland. Tallgrass prairies are marked by very fertile soil conditions. Over centuries, deep rich topsoil developed in this region where adequate summer rains fueled abundant plant growth, and winter snows helped plants decompose slowly into organic, fertile, humus. Almost no tallgrass prairie remains in the US. It’s all been plowed under for agriculture.

Figure: US - Each point on this map represents 10,000 acres of grain corn harvested in 2012. Note the steep decline west of the 100th meridian. Source: USDA

Farmers on flatlands west of the 100th meridian tend to plant wheat. Farmers in this region would probably prefer to plant soybeans and corn because they are more profitable per acre (see the case study on the economics of corn below). West of the 100th meridian, it is generally too dry for corn and soybeans, so farmers plant wheat instead. The wheat belt extends from the panhandle of Texas up through the Dakotas, in a region that was originally dominated by short grass prairie before it was converted to agriculture. The soils of shortgrass prairie are less productive than those created by tallgrass prairies because the region’s dryness both slows plant growth in the summer and provides a less reliable snowpack in the winter thus reducing the effectiveness of the decomposition processes that turn dead plants into soil.

Figure: US - Each point on this map represents 1,000 acres of wheat harvested in 2012. Note its predominance west of the 100th meridian, and compare it to the corn map. Source: USDA.

There are hundreds of types of wheat, but American farmers favor only a few varieties. Farmers plant winter wheat in the fall and harvest it in the early summer. Winter wheat accounts for about three-quarters of all the wheat produced in the US, and we used it to make bread and rolls. Kansas is at the heart of the winter wheat (formal) region. Further north, in the Dakotas, wheat farmers favor spring wheat. They plant it in April and harvest it in the fall. Bakeries use flour made from spring wheat to make dough for pastries and cakes. Durum wheat is a special variety of spring wheat, planted mostly by Americans in North Dakota. Pasta makers prefer Durum wheat to make the semolina flour used in the production of pasta. Durum is a beloved wheat variety of Italians as well.

Wheat is the leading agricultural export from the US, and the US leads the world in wheat exports, but thanks to shifting government policies and climate change, wheat production has fallen in the US since the 1970s. Since 1900, the length and timing of growing seasons have changed so much that corn production is displacing wheat production in regions where the growing season was once too short for profitable corn production. For example, in North Dakota, the first killing frost of the year is now often in October, rather than September asit was for centuries. This allows corn plants to ripen a few weeks longer, and as a result, corn is now more profitable than wheat even in North Dakota - especially given the subsidies for corn production (see below). An interesting positive externality of climate change has been that the alarming out-migration of young people from North Dakota has slowed as farming has once again become profitable in the north-central United States.

Irrigated Drylands

In some arid regions, including parts of California and Arizona, farmers apply vast amounts of irrigation water to fields that would otherwise be too dry for most crops. Elaborate systems of dams, irrigation canals, pumping facilities, and water storage facilities, built with taxpayer funds, allow farmers in arid regions to grow an enormous variety of foods and sometimes reap great profits. Because the Southwestern US has abundant sunshine, long growing seasons, and in many places, excellent soils, the addition of irrigation creates exceptionally productive, and profitable farmlands. Perhaps the greatest irrigated farmlands in the world are found in California’s Great Central Valley where individual counties have larger farm economies than most US states. Most of the fruit and vegetables that you’ve eaten in your life came from irrigated fields in California

Figure: US - Point map of Tomato acreage in the US. Most tomatoes in the US are grown on irrigated fields in California's dry Great Central Valley. Source: USDA.

Fruit and vegetable farming, like that practiced in California, is often the most labor intensive style of agriculture in the United States, requiring large numbers of farmworkers to pick, process, pack, and ship fruits and vegetables because few machines are capable of doing these tasks. Because low-wage laborers both willing and able to do this kind of work are critical to the profitability of fruit and vegetable farming, immigrant labor is highly desirable. California’s Great Central Valley has been for many decades a point of entry for many thousands of immigrants seeking to live in the United States. Many migrants find work in the fields for some years before moving on to other occupations. Immigrant farm workers fundamentally alter the societies where they live in terms of culture and the economy. Debates rage both in the US and internationally about the benefits and costs of immigrant labor, especially when the immigrants are undocumented. Two points are irrefutable. First, very few American citizens are willing to work picking fruits and vegetables for the prevailing wages offered to farmworkers. Two, if farm wages rose enough to attract native-born workers (say, $20 to 30/hr.), the fruits and vegetables would become too expensive to be competitive with those grown outside the US, and the farm economies in the US that are dependent upon immigrant labor would suffer. The issues surrounding farm economics, environment, politics, demographics, culture, and foodways represent a classic example of the concept of cultural integration and the value of a spatial geographic framework for understanding.

Wages rise on California farms. Americans still don’t want the job.

Los Angeles Times March 17, 2017

Red Dirt and Chickens

In the Southeastern US and the Pacific Northwest, over-abundant rainfall makes it difficult to profitably grow many crops. In damp climates, numerous diseases attack plant roots. Insects and other blights also undermine farm profits in humid locations. Also, soils in many parts of the southeastern US are leached because over abundant rainfall washes away many of the nutrients necessary for vigorous crop growth. The famous “red dirt” of Georgia and Alabama is not ideal for many crops. Still, farmers adapt and they search for agricultural activities that maximize the potential of local soils and climate. In both the Pacific Northwest and Southeastern US, where pine trees grow well in poor soil, harvesting timber provides an alternative to row crops. However, lengthy harvest intervals make forestry less reliably profitable. Another common option is to focus on raising poultry. Southeastern states dominate the “broiler” industry – chickens raised for meat. In the Pacific Northwest, marijuana has become the leading agricultural pursuit.

Figure: Cottondale, AL -The presence of reddish soil and pine trees is an indicator of the limited agricultural possibilities at this location. Geographers read this also as an indicator of the economic profile of the region.

Figure: US - Southeastern states dominate chicken production in the US. Source: USDA

Specialty Crop Areas

In some locations, peculiar local soil and/or climate conditions allow farmers to grow very specialized crops. Sometimes these crops are very profitable because they grow well in so few locations. This reduces the supply of the crop, and if demand is high prices will follow, according to the economic model of supply and demand. You can probably think of several locations that specialize in very specific crops. Idaho is famous for its potatoes. Georgia is famous for peanuts, peaches, and onions. Washington is famous for apples. Thanks to irrigation and its rare Mediterranean climate, farmers in California are the dominant producers of many crops including broccoli, carrots, cauliflower, celery, lettuce, and spinach. California farmers grow more than 99% of America’s almonds, artichokes, dates, figs, raisin grapes, kiwis, olives, pomegranates, pistachios, and walnuts.

Figure : Peaches, peanuts and onions are three crops that grow well in specific places in Georgia. Many other locations in the state are poor for agriculture.

Dairy Lands

Dairy farmers raise milk cows across the US. The Northeast and Great Lakes regions are famous for their vast herds and are known as “America’s Dairyland.” California produces more milk than any other state, despite not having a reputation as a dairy state. Dairy farming is nearly ubiquitous across the US because almost everyone drinks milk, and it is perishable. Regions with large populations create high demand for milk, and since milk must be transported quickly to market, the map of milk production echoes the map of the population. Each large city has a regional hinterland of milk production known as a milkshed. Milksheds were once found in about a 50-mile radius around cities, but now thanks to improvement in refrigeration and transport speed, milksheds have radii of over 500 miles.

Figure: US - Dairy farms are generally near population centers - New York, Illinois and California Source: USDA

Most European Americans are lactose tolerant, which boosts demand for milk, cheese, butter, and ice cream. This seems especially true in places like Wisconsin, where a pronounced Germanic heritage exerts a strong influence on regional demand for dairy products. This is an example of cultural integration because patterns of regional ethnic heritage affect regional agro-economics.

Hay farming, which supports the dairy industry, also tends to be co-located with dairy regions because milk cows are fed a steady diet of hay, especially during winter months when field grazing is limited.