6

Erasing Nature

If nature is embodied in natural ecosystems and native species, then agriculture is decidedly unnatural. Agriculture is the way we organize the environment to make food and fiber. Farmers take a piece of land and replace the existing flora and fauna with species they choose themselves. And it’s almost always the same few species: according to the United Nations’ Food and Agriculture Organization, twelve plant species provide 75 percent of our total food supply, and only fifteen of the 50,000 known species of animals account for over 90 percent of all livestock production. Humans and our few domesticated plants and animals use up most of the Earth’s fertile habitat. There are surprisingly small populations of wild animals left in the world, and they usually live on the least productive land. Agriculture has edged nature almost out of existence. As a result, the way we practice agriculture has an enormous impact on what little nature is left.

Until recently, farming had required unending amounts of labor. Trees had to be cut and the stumps grubbed; the earth had to be de-rocked, turned, planted, cultivated, weeded, watered, and then the hard work of harvest began. Before the internal combustion engine was invented, the only practical sources of farm labor were domesticated animals and humans. Repetitive, physically demanding, and never-ending labor led agricultural societies to embrace the caste system, feudalism, slavery, and eventually automation.

In the New World, European colonists tried to re-create pastoral England with fields of wheat and barley for bread and beer, and pastured farm animals for meat, eggs, and milk. The colonists’ privately owned flocks and herds needed barns for shelter, fenced grazing, and fields hewn from the forest to grow winter hay and fodder. Native Americans harvested wild animals that lived independently in the forest, but the colonists held wilderness and its denizens in low regard. Replacing ancient forests with a civilized landscape of pastures, fields, farmyards, and woodlots was seen as God’s work.

From the very start, Europeans practiced two different types of agriculture in the Americas. There was subsistence agriculture, where the yeoman farmers lauded by Thomas Jefferson grew a variety of crops for their own consumption or for local sale. Families brewed their own beer, made their own bread and butter, and kept a few pigs, chickens, and a milk cow or a flock of sheep. Oxen, mules, or horses were used for power, while parents and children provided the labor. Then there was plantation agriculture, typically an international business where a resident labor force grew products that were sold abroad. The colonies had everything necessary for large-scale agriculture—a temperate climate, fertile soil, and plenty of water—but there weren’t any peasants. Plantation agriculture, as practiced by Thomas Jefferson (who preferred imported wines to homebrewed beer), used enslaved people for resident labor.

For the first 300 years of European colonization, more Africans crossed the Atlantic than Europeans. The most comprehensive analysis of shipping records over the course of the slave trade is the Trans-Atlantic Slave Trade Database, edited by David Eltis and David Richardson. Ship by ship, the database includes information on almost 36,000 slaving voyages. Of the 12.5 million Africans shipped to the New World, about 10.7 million survived the Atlantic passage. Over 95 percent of the people shipped from Africa sailed to the Caribbean and South America, with less than 5 percent disembarking in North America. In total, about 450,000 Africans arrived in the United States before 1808, when importing slaves was outlawed.

From the first days of colonization, New World plantations were part of a global money web based on enslaved Africans, North American land, and European markets. Enslaved people were often mortgaged, and they worked alongside indentured servants and wage laborers to grow tobacco. In the 1600s, landowners in Virginia and the Chesapeake Bay region paid their farm expenses with loans from London bankers and delivered tobacco on consignment to the London docks.

By 1808, the total number of people who had arrived in the United States from abroad included about 450,000 Africans and 680,000 Europeans. Nearly half of all European immigrants arrived as indentured servants, typically bound for three to seven years and usually under the age of twenty-five. Indenture—a contract that binds a person to service for a specific length of time—became less common after the American Revolution, when the relative cost of transoceanic transport dropped and people could afford to buy their own boat tickets. With fewer indentured servants, slavery became more entrenched.

Tobacco, rice, indigo, cotton, and sugar plantations spread from Virginia all the way to the Mississippi floodplains. Each of these crops requires labor-intensive processing after harvest, which provided year-round work for a captive labor force. Cured tobacco, fermented indigo, hulled rice, and deseeded cotton were mostly exported to Europe; molasses and refined sugar were sold in the United States.

Enslaved people and indentured servants did the plantation handwork of tilling, planting, hoeing, harvesting, and processing, while oxen, horses, and mules provided the nation’s agricultural power. Oxen—castrated bulls—were more common than horses until the mid-1800s. Oxen can pull very heavy loads, slowly and steadily, and can clear land, plow heavy soils, and break sod. A plow ox would typically work hard for seven to ten years, and then be fattened up for a few restful months before slaughter.

For thousands of years, oxen have pulled moldboard plows that cut the soil with a metal point called a share or plowshare. The curl of soil is flipped over by the moldboard, making a furrow—a V cut into the field with freshly overturned earth on one side of it. This brings fresh nutrients to the surface, smothers weeds, loosens the soil, and incorporates manure and crop residue into the root zone. Plowing warms the earth in the spring, speeding germination.

In addition to plowing, oxen hauled loads. They are slower than mules or horses, and cheaper: in 1850, a yoke of oxen cost about $50, while a good team of mules could run $200 (about $5,800 today). Oxen can work well eating grass, while working horses and mules need grain to maintain condition.

Oxen are strong and their pace is measured; like mules, they cannot be rushed. Horses are much faster than oxen, and can easily be worked to death. The average lifespan of a horse is twenty-five to thirty years, today. But before the widespread adoption of the internal combustion engine, the average working life of a horse was as low as three and a half years. The horse’s speed and its willingness to be overworked made it the preferred source of power in the early days of the Industrial Revolution.

The Aid Book to Engineering Enterprise Abroad, published in 1878, provides an engineering analysis of the lifespan of a working horse:

In London, a two-horse car, running 70 miles per day, usually requires ten horses, each horse thus having 14 miles of work. But to maintain this service, eleven horses are provided so as to allow for occasional rests. But where the cars are light and the gradients very favourable, horses are worked 16, 18 and even 20 miles per day.… The London General Omnibus Company, by careful selection of their horses, and proper treatment, raised the working-life of the animals from three and a half years to five years.

Enslaved people were routinely worked to death as well.

In total, about 680,000 Europeans and 450,000 Africans had arrived in the United States before the first census was taken in 1810. That year, the census counted almost 7.2 million total Americans, including 3 million white men, 2.78 million white women, and 1.2 million enslaved and 200,000 free people of African descent (the US Census did not count Native Americans until 1860). It was a time of bad nutrition, rampant disease, deadly childbirth, and harsh upbringing. If the survival and reproductive rates for slaves were equal to those of other early Americans, then we can calculate how many people of African descent should have been living in the United States in 1810. With comparable longevity and reproduction, there would have been about 3.8 million African Americans in 1810. Instead, the census counted 1.4 million African descendants. By 1810, this country was already missing 2.4 million black people.

Plantation economics were unforgiving, and plantation agriculture was a rich man’s occupation. At a time when field labor cost up to $10 per month plus room and board, an enslaved person cost about $1,000. Slaves were an expensive investment. In Louisiana, the sugar plantations were funded by mortgage-backed bonds guaranteed by the state and sold to investors in Britain, Europe, and even New York; the bonds paid 5 percent interest, and the work was so brutal that the average lifespan of an enslaved man on a big sugar plantation was seven years. A seminal 1958 study of antebellum economics showed that a single enslaved agricultural worker who bore five children for sale over thirty years earned her owner nearly 7 percent on his capital investment. Plantation agriculture wasn’t all about the crops. Instead, agricultural profit margins were slim (as they are today), and plantation profitability was often based on selling slaves. As Thomas Jefferson wrote, a “woman who brings a child every two years is more profitable than the best man on the farm.”

Thomas Jefferson’s experience as a plantation owner illustrates the point. Jefferson inherited his 5,000-acre plantation, Monticello, at the age of twenty-one. When he died in 1826 at the age of eighty-three, his lifetime of agricultural enterprise had created debts of $107,000, equivalent to about $2.5 million in 2015. These debts were paid after his death by auctioning off his land, buildings, and slaves. In the end, Thomas Jefferson’s heirs sold humans to pay for his French wines.

Labor and power—how to get the work done—is one intractable problem with agriculture, and soil fertility is another. The narrow profit margins for slave-grown commodities led landowners to exploit the fact that the new country was land-rich. Instead of spending labor and money to maintain soil fertility by adding organic matter and rotating crops, slaves carved new fields out of the forest whenever the soil became depleted, usually every ten to twenty years. By the early 1800s, much of the new nation’s farmland was nutrient deficient and eroding. Overgrazing, poor crop rotation, and scant fertilization had worn out the fields.

Crop rotation may sound esoteric, but every farmer sees that a field planted annually with the same crop gives a smaller harvest every year. Pests settle in and multiply, and without precise fertilization, it’s easy for soil micronutrients to become depleted. When a field grows a different crop each year, last year’s insects hatch to find the wrong food, and the exact menu of necessary nutrients changes annually, allowing the soil to replenish itself.

Since the Middle Ages, Europeans have practiced a three-year rotation where one year a field is planted in rye or wheat (for bread), the next year in barley or oats (for beer or porridge), and the third year the field is left fallow, or unplanted. Most farm animals were slaughtered in the fall, because there was too little feed to support a herd through winter.

Charles Townshend, the elegant Second Viscount Townshend, popularized a new system of land management in the 1700s: instead of leaving fields unplanted every third year, “Turnip” Townshend (so-called because that was his favorite topic of conversation) advocated a four-crop rotation between wheat for bread, barley for beer, turnips for cattle, and clover to add nitrogen to the soil and for grazing. This system allowed livestock to be kept year-round and increased the amount of manure available for fertilizer. By adding nitrogen and organic matter to the soil with manure, and by planting nitrogen-fixing crops like clover, crop yields increased along with the farmer’s herds.

Fertilizers include manure, seaweed, or other nutriments, or land can be planted with clover and other legumes that have little nodules on their roots containing symbiotic bacteria, called rhizobia, that fix nitrogen. When the plant dies, nitrogen in the nodules is released into the soil, making it available to other plants. Legumes fertilize the soil, and when they’re included in a crop rotation, there’s no need for a fallow year.

The benefits of fertilizer, crop rotation, and a legume cover crop were understood when the East Coast was first plowed, but land was abundant and there was no obvious need to conserve it. In addition, there was no scientific body of knowledge to help people farm.

In 1760, the first book of agricultural advice in North America was published in Boston: Essays upon Field-Husbandry in New-England as It Is or May Be Ordered by Reverend Jared Eliot. He advocated using fertilizer, planting legumes, plowing deeply, and ditching the lowlands to make fields. The next American book of agricultural advice, also written by a clergyman, was published thirty years later: Reverend Samuel Deane’s The New England Farmer; or, Georgical Dictionary: Containing a Compendious Account of the Ways and Methods in Which the Important Art of Husbandry, in All Its Various Branches, Is, or May Be, Practised, to the Greatest Advantage, in This Country helped the new nation’s farmers meet the demands of an expanding marketplace.

Agricultural production was bumping along until 1815, when Mount Tambora erupted. This Indonesian volcano was the most explosive event in human history, creating an enormous sun-obscuring plume of ash that circled the Earth at the equator in a matter of weeks. The plume then drifted towards the poles, cooling the Earth for three years. Tambora’s layer of volcanic ash darkened the sky, average global temperatures fell between 3°F and 6°F, and rainfall patterns changed dramatically.

Global cooling was an agricultural catastrophe. The year of 1816 became known as the “Year There Was No Summer.” Frosts and floods killed crops throughout the northern hemisphere, and many people went hungry. In Vermont, 1816 was remembered as “Eighteen-Hundred-and-Froze-to-Death,” the year that people ate groundhogs and nettles. There were killing frosts every month, and people left New England in droves for the promised lands of Ohio and Pennsylvania. Across the Atlantic, the Rhine River rose nine and a half feet above its usual level, leaving whole villages under water. In July 22, 1816, the Times of London reported that in Germany, “hopes of a very fine harvest have been almost ruined. The loss in hay, corn, tobacco and pulse is incalculable.” On August 2, 1816, the Times reported from the Netherlands that “indescribable misery has taken place, so that the lower classes of people have been obliged to feed on herbage and grains.”

The worldwide failure of agriculture in the cold, dark years after the eruption of Mount Tambora spurred interest in agricultural science. In 1818, agricultural knowledge was codified in the Farmers’ Almanac, a handbook printed in Morristown, New Jersey. It told farmers when to plant which crops and how to cultivate and fertilize them. People were eager to adopt scientific practices, and quickly embraced both the Farmers’ Almanac and the reverends’ agriculture books from the 1700s.

Fertilizer is part of our national mythology: schoolchildren are taught that Squanto showed the Pilgrims how to plant each corn hill with three fishes, so the corn would grow strong. This story is likely apocryphal, but perhaps it’s so widely known because it speaks to the bone-deep human urge to increase crop yields. Fertilizer is like pixie dust that might grow giant vegetables, and long before Miracle-Gro swept the market, every gardener believed in the possibility of a perfect soil amendment. Manure is one of the oldest, easiest fertilizers except that it has to be mixed with a carbon source (like yard wastes or animal bedding) and composted before it can be used as a soil amendment. The pile heats up as the manure breaks down, and then the pile needs to be inverted so the wastes and weed seeds are uniformly sterilized. Over the years, Bob has composted mountains of cow manure, horse manure, and sheep manure, turning the piles neatly with a tractor bucket. (This year, the manure from a flock of forty sheep is scheduled for delivery in April.) Composted manure is an old favorite, but fertilizer goes by fashion as well. Volcanic dust, water from the bottom of a pair of seventy-gallon tanks stocked with carp, beneficial bacterial brewed up in the next town and sold by the gallon: I’ve tried them all, because the exact combination of supplements to make your plants flourish is always a bit of a mystery.

The three main macronutrients in any fertilizer are nitrogen, phosphorus, and potassium. At the time Mount Tambora erupted, nitrogen sources included blood, fish, and manure; phosphorus from rock phosphate, bones, fish, and seaweed; potassium from greensand, kelp, and ash. Agricultural science promoted these fertilizers (still popular today, and I have sacks of most of them), but the favorite product was South American guano.

Guano (from the Quechua wanu) is the accumulated feces of seabirds, bats, or seals that is aged and ready for direct application. The social behavior of these animals creates guano in huge, concentrated, ever-increasing piles. Made almost entirely of nitrogen, phosphate, and potassium, guano is an ideal fertilizer.

Peruvian guano has been used as a fertilizer for centuries. Garcilaso de la Vega wrote in the 1609 Royal Commentary of the Incas, “They use no other manure but the dung of sea birds, of which large and small varieties occur on the coast of Peru in such enormous flocks that they seem incredible to anyone who has not seen them.” The Humboldt Current carries cold, nutrient-rich Antarctic waters up the Peruvian coast that feeds shoals of anchoveta, an anchovy relative. For thousands of years, millions of cormorants, pelicans, and boobies ate anchovetas and shat on a chain of coastal islands, where the extremely dry climate preserved millions of tons of bird feces. The largest reserves of marine phosphorus in the world were piled into mesas more than 150 feet high on the Chincha Islands off Peru’s southern Pacific coast.

Alexander von Humboldt, the Prussian naturalist and geographer, was the first European to promote guano. He was in Peru taking temperature measurements of the soon-to-be-named Humboldt Current, and often went down to the piers where guano was being unloaded. Humboldt brought samples of guano back to Europe in 1804, and turned them over to “the best analytic chemists of the day.” His widely read essays on the efficacy of fertilizing with guano resulted in a guano boom. As Gregory T. Cushman wrote in Guano and the Opening of the Pacific World, thus began the world’s guano age. Representatives from Britain’s Antony Gibbs and Sons formed a joint venture with the Peruvian government in 1841, and soon about 300 ships laden with guano were leaving Peru every year.

The Peruvian government used convicts, indentured Chinese, and kidnapped Polynesians to mine their guano islands. The first group of seventy-nine indentured Chinese workers arrived in 1849, and eventually more than 100,000 indentured workers were imported from China to harvest Peruvian guano. The Peruvians and Chileans nearly depopulated Easter Island and Tongareva, kidnapping whole villages and forcing them to live and work mining bird feces on the Chincha Islands.

Peru’s guano boom lasted from 1840 to 1870, with 12 million tons of guano shipped to Europe and North America, valued at $500 million. In 1877, A. J. Duffield noted that “it is only in Peru that we find an epoch of Gold and Silver juxtaposed with an Age of Manure.” European-style agriculture’s dependence on guano deposits faded after 1909 when Fritz Haber developed the Haber-Bosch process of industrial nitrogen fixation. Today, ammonia-based fertilizers are responsible for feeding perhaps one-third to one-half of the Earth’s population.

Fertilization and crop rotation are simple ways to increase crop yields, but reducing the labor required to run a farm took machines, invention by invention. Until Jethro Tull’s seed drill was invented in 1701, a field had to be sown with the seeds scattered by hand and the ground harrowed to cover the seeds, or hand-planted with a few seeds put into a small hole and covered, hole after hole after hole (stoop labor at its finest). A seed drill efficiently plants the seeds and covers them to a specific depth, ensuring that more seeds sprout. It takes far less labor than hand planting, and seed drills became common in the 1800s. In modern-day Vermont, a single seed drill is shared by the whole neighborhood.

As plants grow, it is useful to hoe between the rows to kill weeds and loosen the soil, and Jethro Tull’s horse-drawn hoe was the first time a field could be cultivated with horses instead of humans. Grain was harvested with scythes, and then threshed in a labor-intensive process of beating the harvested grain to separate the grain from the stalks, and to separate each grain from its protective husk, or chaff. Grain was threshed with a tool made of two sticks of wood with a hinge in the middle, unchanged since Roman times. A man could flail seven bushels of wheat, eight of rye, fifteen of barley, eighteen of oats, or twenty of buckwheat in a day.

For 2,000 years, about a quarter of all agricultural labor was used for threshing with everyone wielding the same stupid flail until Andrew Meikle’s steam-driven thresher, patented in 1788, became common in the 1800s. Thomas Jefferson owned three threshing machines by the time he died, and ordered one of Meikle’s threshers from London in 1792. It took nearly a year to arrive and was eagerly awaited. In a letter to James Madison, Jefferson wrote,

I expect every day to receive from Mr. Pinckney the model of the Scotch threshing machine.… Mr. P. [Pinckney] writes me word that the machine from which my model is taken threshes 8. quarters (64. bushels) of oats an hour, with 4. horses and 4 men. I hope to get it in time to have one erected at Monticello to clean out the present crop.

In the 1800s, new farm machines reduced the need for both power and labor. A hundred bushels of wheat required 300 labor hours in 1800, 50 labor hours in 1900, and 3 labor hours in 2000. Farming became much more efficient, and better transportation allowed crops to reach local markets. When Jefferson ran Monticello, it cost less to ship a crop to Europe than to move it thirty miles inland. Transportation slowly improved with turnpikes, canals, and finally railroads. First, the turnpike network of privately owned and operated roads expanded rapidly in the early 1800s. Water transportation improved when canals connected different river systems. The Erie Canal, completed in 1825, connected the Great Lakes to the Hudson River and allowed lumber, coal, and hay from the entire Great Lakes region to be barged to New York City. The Illinois and Michigan Canal connected the Great Lakes to the Mississippi River in 1848. Finally, railroads superseded the canal system and trains generally brought crops to market in the second half of the 1800s.

Both land and population expanded dramatically. The 1803 Louisiana Purchase and the subsequent destruction and eviction of Native American tribes from Florida to Minnesota brought vast tracts into European-style cultivation. To farm the newly depopulated land, the federal government issued 160-acre lots to about 400,000 families through the Homestead Act. The railroads were deeded millions of acres of public land, and to sell it they provided low fares from Europe to coax hundreds of thousands of farmers from Scandinavia, Germany, and Great Britain to immigrate. The number of farms in the United States tripled between 1860 and 1905, from 2 to 6 million.

Since then, the amount of cultivated and grazed land in the United States has held steady. Almost one in every five acres in the continental United States is plowed as cropland, and an additional two in every five acres are grazed as rangeland. Native plants and animals are excluded from land used for cultivated crops like vegetables or grains. Orchard crops like fruits or nuts can have native vegetation under the trees, and grazing land for cattle or sheep can be shared by a variety of native plants and animals. Eating grass-fed meat, fruits, and nuts can support native ecosystems, but eating vegetables or grain generally does not. Instead, our chosen plants and animals have replaced nature in nearly every river valley and on the most productive land. Much of the land reserved for wildlife is desert scrub and steep mountains.

The expansion of farmed land was accompanied by a second wave of agricultural improvement. Land grant colleges date back to 1862, when Abraham Lincoln signed legislation that granted each state public land to fund colleges of agriculture and the mechanical arts. Since then, every state has a center of agricultural expertise. The extension service started in the 1880s with the intent of providing an agricultural expert for every county in the United States.

The extension service gave local farmers access to the latest advances and varieties, and it still works well. Today, if your plants or animals are hit by an outbreak of disease, the extension agent will tell you who else is affected and explain your treatment options. You can bring in insects, damaged fruit, or diseased leaves and have your problem diagnosed. You can bring in your soil for analysis, get the test results explained, and have the appropriate amendments for your acres laid out like a shopping list. The extension service still provides every citizen with a personal agricultural consultant, no appointment necessary and no bill, in nearly every county. My agent is a local hero; he’d blush if he knew how much people truly appreciate his guidance. I have questions for him every year, and they’re always answered.

It is difficult to grow things well, and takes both information and hard work. Bob planted an orchard in Vermont on a west-facing slope above the house. We planted a total of 160 trees on twenty-five-foot centers, filling less than three acres. He got the trees from David Fried, a nurseryman who was making a big effort to propagate old-time varieties of apples. David spliced twigs from heirloom apple trees gathered from abandoned orchards onto a cold-hardy Russian rootstock, making sturdy northern trees. According to him, certain varieties prefer to be planted together; some were good for the crest of a hill; and some varieties needed to be planted in a location with less wind.

The trees arrived bare-root and we had to get them into the ground as quickly as possible, so there was a long checklist to be completed before they came. We needed 160 holes, but learned that when you pile soil from the hole onto the ground, too much dirt is lost in the grass to refill the hole. Bob got a stack of burlap bags from Green Mountain Coffee Roasters to pile the dirt on, one per hole. The trees had to be top-dressed with compost, so he got a truckload of horse manure and turned the pile twice before the trees arrived. We bought a hundred pounds of black rock phosphate and a hundred pounds of Jersey Greensand.

The trees were laid out on a twenty-five-foot grid that sprawled over three small slopes interrupted by two swales. Bob paced out the orchard and marked each hole with a stake, a task done with such concentration that twenty years later, he can still pace out twenty-five feet to within a few inches. Each tree needed a hole roughly a foot in diameter and a foot and a half deep, so we hired a man to dig them and leave a pile of soil neatly mounded on burlap beside each one.

The adult size of a tree is based on the rootstock, and you can choose any variety in either dwarf, semi-dwarf, or standard size. The rootstock determines a tree’s cold tolerance, and how quickly it grows. We chose standard trees, hoping to maximize the yield per acre.

The trees arrived in bundles of a dozen whips with bare roots, wrapped in burlap that had to be kept moist. Each tree had a squiggled taproot of less than a foot, and a slender whip above that was no more than four feet high. For planting, each hole got a handful of Jersey Greensand, a handful of black rock phosphate, and two cups of a locally made organic fertilizer. Adding a little soil and some water to the hole allowed us to mix it into a slurry, and then it was a two-person job: one person holding the tree in place, and the other filling the hole with soil and water, building up the soil around the tree until the hole is filled. When the whip is straight, upright, and centered in the hole, you form a ridge of soil and grass around the edge of the hole to hold water in place, and move on to the next tree.

From that day on, the biggest problem was keeping the young trees watered. Bob bought a 300-gallon tank for the back of the truck, with a hose attached to the tank. He watered each tree once a week for their first summer and fall, and once a month through the winter and the next year.

There was no need for a deer fence in that location. Instead, mice were the tree-killers. They would scamper over the top of the snow, and stop by each whip to girdle the trees by eating the cambium layer, often six or eight inches above the ground. Each whip had a screen around its spindly little trunk from about an inch underground to a foot or so aboveground to protect it from mice, and later to protect it from being stripped by the weed whacker when cutting the grass low around each tree. Finally, Bob painted each tree’s little trunk with white latex paint on the south side, because the winter sun on dark bark can be so hot that the bark splits open, wounding the cambium layer.

You couldn’t believe how fast those trees grew. Pruning is serious business, because you cannot alter a tree’s eventual height, but you can determine its shape. The natural shape of an apple tree does not maximize fruit production, and the purpose of pruning is to help the tree form a strong framework. The first pruning, the winter after the whips took root, was to ensure that each tree only had one leader and to cut the whip to stimulate the growth of the remaining buds, encouraging branching.

The second winter pruning is to reduce any legginess. You cut branches that are too vertical and one branch of every forked limb. The young trees grow quickly, and require steady attention to guide them into the open, strong-limbed shape that will produce the most fruit. Your goal as a pruner is to allow each tree to express its true nature. Pruning is tough.

There’s nothing easy about this project. You have to choose your crop, varieties, and soil amendments, then you source materials, figure out the labor, and pay attention for years to make a profit. And then the pests descend.

With larger fields, more farms, and monoculture—the practice of raising a single crop in an area—pests and diseases flourished. The Colorado potato beetle, indigenous to a small region in the southwestern United States, spread to cover about 3 million square miles of North America. Pests multiplied, and hunkered down.

Organic pesticides have been used since the 1600s when rotenone, extracted from the roots of several tropical and subtropical plant species, became popular in Europe and the United States for controlling caterpillars. Pyrethrums, called Persian or Dalmatian Insect Powder and made from imported chrysanthemums, were dusted on aphids and caterpillars. Tobacco extract was used to control ants and lace bugs, and it works (if you want to get rid of an ant’s nest, boil up a pack of chewing tobacco in a big pot of water, and pour the tobacco tea on the nest).

Toxic inorganic pesticides debuted in 1867 with the invention of Paris green, a mixture of arsenic and copper sulfate. This was the beginning of chemical warfare against crop pests, and many other compounds followed. It was also the peak of horse labor. There were 25 million horses and mules in the United States in 1910, more than one for every four US citizens. One-quarter of all cropland was used to grow hay and oats for horse feed.

Horses were replaced function by function. Streetcars replaced horse-drawn omnibuses by the 1900s, cars took over for the horse and buggy next, and motorized trucks finally hauled more freight than horse carts in the 1920s. Tractors had been invented decades earlier, but were too big and costly for farmers to buy: they weighed more than an elephant and were nearly as expensive.

Henry Ford introduced the Fordson in 1917, a smaller, cheaper tractor for the masses. Round after round of new technologies followed. Power lifts, rubber tires, and diesel engines eventually made tractors more practical than horses. Every tractor displaced about five horses, and it was not until the 1940s that tractors provided more horsepower than animals.

Cultivation was confined to the East Coast for the first 200 years of settlement, wearing out the soil, but in the 1800s, millions of immigrants took their oxen west and plowed the Plains. By the 1900s, mechanization reduced the need for farm labor, horses replaced oxen, and 60 percent of all land was used to produce food. Since then, our footprint on the landscape has remained the same, but we produce much more food per acre, and feed about 10 million indolent horses today instead of 25 million hardworking horses a century ago.

We have taken the best three of every five acres for domesticated plants and animals, and left much of the rest as forestland. But to make the country safe for cattle and sheep, we killed nearly all of the large predators, everywhere. Grizzlies and black bears, mountain lions, lynx and bobcats, wolves, coyotes, badgers, and wolverines were almost eradicated. When you remove the apex predator from an ecosystem, populations of their corresponding prey species multiply, with unpredictable outcomes. When wolves were returned to Yellowstone, they hunted for elk and deer along the river’s edge. The grazers no longer stripped the riparian vegetation, so young adult beavers had places to hide during those vulnerable months when they leave their home ponds to set up dams of their own. The wetlands multiplied and more water was retained in the valley, increasing the land’s productivity. In Yellowstone, wolves raised the water table. Apex predators reorder an ecosystem in unexpected ways.

I wish I could say that agriculture and nature have maintained an uneasy truce since the early 1900s, but that would be incorrect. Removing predators across the continent upended natural ecosystems. Nature was rearranged, and has not been restored.