Agricultural machines

Agriculture is an endeavor practiced in all countries. From the earliest times, humankind has engaged in some form of planting, herding, or gathering. From about 11000 to 8000 BC in the Middle East, where many consider civilization to have begun, early farmers used crude flint-edged wooden sickles to harvest wild grains growing on the river banks. The harvested grain was often stored in caves for use during the fall and winter. Unfortunately, there was often not enough to gather and store to feed the growing population.

Soon local tribes learned how to plant and cultivate the seeds of wild grasses and raise them as food. About 9000 BC these same Middle Eastern tribes learned to domesticate sheep and raise them for both their skins and food. Communities grew along the rich, fertile banks between the Tigris and Euphrates Rivers in Mesopotamia (now Iraq). Here in the cradle of civilization the first true machine, the wheel, was invented and used on animal-drawn carts in the expanding fields. For the first time, canals were built linking the principal rivers with local tributaries. Pulleys were used to draw water from the canals creating the first irrigation system.

Early farmers quickly learned that a supply of water was essential to farming. Thus, the primary fields of grain were planted alongside the great rivers of the Middle East. However, getting water from the rivers to the fields became a problem. The invention of the shaduf, or chain-of-pots, helped solve this problem.

This human-powered primitive device consisted of buckets attached to a circular rope strung over a horizontal wooden wheel with wooden teeth projecting at the rim. The buckets were lowered into the water by this revolving chain, and water was lifted from the river and carried to the fields.

The first farming tool was a pointed stick called a digging stick. The food gatherers used it to dig roots; later farmers used it to dig holes for seeds. The spade was invented by the farmer who simply added a cross bar to his digging stick so that he could use his foot to drive it deeper into the earth. A stick with a sharp branch at one end was the first hoe. Later, a stone or shell was added to the stick to give it a more effective cutting edge. Sharp stones cut along one edge converted a stick into a sickle.

After animals were domesticated for food, they were soon trained to become beasts of burden. Sometime around 2300 BC, along the Indus River of northern India, water buffalo and zebu cattle were used to pull crude wooden plows through the earth, thus developing the practices of plowing and cultivating.

The discovery of metal at the end of the Neolithic period (or the New Stone Age), possibly sometime in the second millennium BC, enabled farmers to have sharper, stronger blades for hoes, plows, points, and sickles. The Romans improved the design of their agricultural implements, leading to vastly improved plows and sickles using metal parts. They raised olive and fig trees as well as cereal grains; they also kept vineyards, many of which are still bearing.

The Roman plow consisted of two wooden planks in the shape of a “V.” At the base of the “V,” a metal tip was attached. At the back of the “V,” an upright wooden post allowed a farmer to guide the implement. A pair of oxen was required to pull the crude plow known as an aratrum. This rather basic tool could not plow a furrow or cut a slice of soil and turn it over as modern plows do. Since this two-ox aratrum merely scratched the soil, it was necessary to go back over the first-plowed earth again and cross-plow it at right angles to the initial pass.

The basic plow was one of the farmer’s most important implements, yet it remained unchanged for centuries. Until the 1800s, the plow was still a heavy, pointed piece of wood that was pulled by several oxen and dug an irregular furrow. It did not turn the soil. In 1793, American president, scientist, and inventor Thomas Jefferson developed a curved iron mold-board, made according to a mathematical plan, that would lift and turn the soil yet offer little resistance

to the motion of the plow. His idea was never tested. However, four years later, New Jersey farmer Charles Newbold patented a plow with a cast iron curved mold-board similar to the idea Jefferson proposed. Ironically, farmers were slow to accept the device, many claiming that cast iron would poison the soil and encourage the growth of weeds. In 1819, Jethro Wood followed Newbold’s design with a cast-iron plow incorporating detachable parts that could be replaced when worn. Soon, more and more farmers recognized the advantages of the new design and slowly began to accept the concept of a metal, curved blade or moldboard.

However, as men began to plow the plains, cast iron plows proved to have a major disadvantage: soft or damp soil easily clung to the blade and made a full furrow difficult to achieve. James Oliver, a Scottish-American iron founder, developed an iron plow with a face hardened by chilling in the mold when it was cast. His device solved some of the previous problems. By the time of his death in 1908, his invention had made him the richest man in Iowa. Yet, even the Oliver plow had problems with the heavy, sticky soil of the prairies. Soil still stuck to the moldboard instead of turning over.

The steel plow was the answer to this problem. In 1833, John Lane, a blacksmith from Lockport, Illinois, began covering moldboards with strips of saw steel. For the first time a plow was successful in turning the prairie soil. Then, in 1837, a blacksmith from Grand Detour, Illinois, named John Deere began making a one-piece share and moldboard of saw steel. Within 25 years, the steel plow had replaced the cast iron plow on the prairies. Demand for Deere’s plow was so great he had to import steel from Germany. Today, the company that bears his name, based in Moline, Illinois, is one of the world’s leading manufacturers of farming implements.

The Romans are also credited with the invention of a crude machine used to cut, or reap, wheat. It was called Pliny’s reaper, not because Pliny was the inventor but because the great Roman historian mentioned it in his writings around AD 60. Pliny’s reaper consisted of a wooden comb affixed to the front of a wooden cart. The cart was pushed through the fields by an ox. A farm hand guided the grain into the comb’s teeth and manually sliced off the heads of the wheat, allowing the grain to fall into a trailing cart and leaving the straw standing. This was a disadvantage where the straw was valuable as fodder.

Another agricultural development also occurred about this time. For thousands of years the only tool used to separate, or thresh, the grain from the straw was a stick that literally beat the grain from the straw. In warm climates, animals were used to walk on the wheat, or tread out the corn. However, in the colder climates of central and northern Europe, where the weather was uncertain, threshing was done by hand in barns.

Then, during Roman times, a farmer decided to lash two strong pieces of wood together with a leather thong. By using one stick as a handle and whipping the grain with the other stick, he could swing his device in a circular motion rather than the up-and-down motion used previously. Thus, a great deal more grain could be threshed. The invention was called a flagullum after the Latin word meaning a whip. It was later simply called a flail. After the fall of Rome, no further advances in reaping machines were made for 15 centuries.

During the Middle Ages, agricultural hardware also made slow progress, yet some gains were recorded. Around AD 1300 a new type of harness was developed that radically changed farming. This simple device allowed a horse, rather than an ox, to be hitched to a plow. Since a horse can plow three or four times faster than on ox, horses gradually replaced oxen as the chief source of power.

During the early 1700s, several major changes in agricultural machines were made. In this period, known today as the Agricultural Revolution, inventors in Great Britain and the United States introduced machines that decreased the amount of labor needed and increased productivity.

For centuries farmers had planted seeds by sowing or scattering them on the soil and trusting chance to provide for germination and a decent crop. Sowing seeds was both labor intensive and extremely wasteful, as many seeds never grew into plants. Next, farmers tried digging a small trench and burying their seeds. This method improved the yield, but was even more labor intensive. Then, in 1701, English farmer Jethro Tull invented a horse-drawn device that drilled a preset hole in the soil and deposited a single seed. It was the first successful farm machine with inner moving parts and the ancestor of today’s modern farm machinery.

Harvesting of grain is perhaps the most difficult job for farmers, and for hundreds of years all the work was performed by human hands. Horses and oxen had been used to pull plows, but harrows and carts were of no avail at harvest time. Only hours of backbreaking toil could cut and bind the grain before it rotted on the ground, a window of about ten days. At best, bringing in all the grain was uncertain; in cases of bad weather or too few laborers, it could result in famine.

The principal implement of the harvest in the earliest recorded days of history was the sickle, a curved knife with which a strong man could cut a half acre in the course of a day. Harvesting with a sickle, however, is grueling labor. Each bunch of grain must be grasped in one hand and cut by the sweep of the blade. In 1830, the sickle was still in general use under certain crop conditions.

The scythe was an ancient tool used for cutting standing grain. With it, a man could cut two acres a day. During the eighteenth century, the scythe was improved by the addition of wooden fingers. With this implement, called a cradle, grain could be cut and at the same time gathered and thrown into swaths, making it simpler for others following to bind it into sheaves.

It was during the late eighteenth and early nineteenth centuries that American ingenuity altered centuries of farming practices. In 1793, for example, a young Connecticut resident, Eli Whitney, graduated from Yale University and went to live on a cotton plantation in Georgia. There he observed the slaves picking cotton. Each slave slowly separated and stripped the cotton fiber from its seed. However, the cotton clung so tenaciously to the green seeds that a slave working all day could only clean a single pound of cotton. Whitney recognized the problem and designed a machine to separate the cotton fibers from their seeds.

His device, called a cotton engine (the word engine was soon slurred to gin), consisted of a cylinder from which hundreds of wires (later changed to sawtoothed disks) projected. The pieces of wires worked in slots wide enough for the cotton but not wide enough for the seeds. As the hooks pulled the cotton through the slots, a revolving brush removed the cotton from the cylinder.

The cotton gin alone altered the entire economy of the South and the nation. In the year following Whitney’s invention, the cotton crop increased production from five to eight million pounds. Six years later, in 1800, 35 million pounds were produced. By the time Whitney died in 1825, more than 225 million pounds of cotton were produced each year. The invention of the cotton gin led to the expansion of the plantation system with its use of slave labor and led to the South’s dependence upon a single staple crop. It also encouraged the economic development of the entire nation by providing large sums for use in foreign exchange.

The invention of the reaper was probably the most influential in the history of agriculture. It greatly reduced the threat of famine in America and released thousands of men from the farm. Before the early 1800s, 95% of the world’s population was needed to work on the farm. In 1930, 91% of the 220 million Americans were living in cities and small towns, with only 4% living on farms.

Many inventors worked on animal-powered machines for harvesting grain. In 1828 alone, there were four patents issued in England for reaping machines. None were successful. However, in 1826, Scottish inventor Patrick Bell developed a machine that consisted of two metal strips, one fixed and the other oscillating back and forth against it. As the machine moved forward, the metal strips sliced the grain. Although Bell’s machine was an effective grain harvester, he was discouraged from requesting a patent by angry farm workers who feared for their jobs.

About the same time as Bell was working on his machine, a Virginian of Scottish-Irish parentage, Cyrus H. McCormick, was also trying to produce a machine that would successfully harvest grain. In 1831, McCormick demonstrated his first reaper before a skeptical gathering near his father’s farm near Steel’s Tavern, Virginia. The trial failed because the field was too hilly, but when another farmer offered his acreage on a flatter field, the test was a success. Although McCormick’s first device was still in a crude state, it cut as much grain as six laborers working with scythes or as much as 24 could cut with sickles.

His harvester combined a number of elements, none of which were new, but had never been combined before. He used a reciprocating blade similar to Bell’s design. A reel pushed the grain against a blade. The harvested grain fell onto a wooden platform located beneath the blade and was swept into swaths by a laborer standing astride it.

Despite the fact that the machine worked, no one was interested in buying one for $50. The following year McCormick demonstrated an improved model at Lexington, California, and still found no buyers. By 1840, his total sales amounted to one. He increased the price to $100 and in 1842 sold seven. By 1845, he had sold close to 100 reapers and word of their successful achievements began to spread. McCormick moved to Chicago, Illinois, and formed his own company to manufacture reapers. By the time he retired as a wealthy man, his son had taken over the business, which was later merged to become the International Harvester Company, now Navistar International Corporation.

Other horse-drawn machines followed the improved plows and grain reapers. In 1834, threshing machines were first brought to the United States from Scotland, where they had been used since 1788. A successful American thresher was patented in 1837. The following year the combine was introduced on the American farm, and for the first time a machine combined both the harvesting and threshing of grain. These early machines were large and bulky and required horse or mule teams to pull them. It was not until the 1920s, with the successful introduction of gasoline-engine tractors, that combines were accepted on farms. By 1935 a one-man combine was in use, and by the agricultural boom of World War II, self-propelled combines were common.

Other American patents were granted in the 1840s and 1850s for an improved grain drill (thus making obsolete the sowing of seeds by hand), a mowing machine, a disk harrow, a corn planter, and a straddle row cultivator. The Marsh harvester, patented in 1858, used a traveling apron to lift the cut grain into a receiving box where men, riding on the machine, bound it in bundles. Early in the 1870s, an automatic wire binder was perfected, but it was superseded by a twine binder late in the decade.

Although animal power was still required, the new agricultural implements greatly saved both time and labor. During the period between 1830 and 1840, for example, the time required to harvest an acre of wheat was reduced from 37 hours to about 11 hours.

With the introduction of steam power in the early part of the nineteenth century, the days of animal powered machines were numbered. Shortly before the Civil War (1861–1865), the first steam engines were used on farms. Initially, these heavy, rather crude devices were used in the field to provide belt power for threshing machines or other farming jobs that could be accomplished at a stationary location. During the 1850s, self-propelled steam tractors were developed. However, they required a team of men to operate them. A constant supply of water and fuel (usually wood or coal) was required; someone was also needed to handle the controls and monitor the boiler.

Huge steam tractors were sometimes used to pull a plow, but their use was extremely limited. Because of its cost, size, and the general unwieldiness of the machine, it could only be employed profitably on the immense acreages of the western states. The first internal combustion tractors, built near the beginning of the twentieth century, were patterned after the steam models. And, like their steam predecessors, the first gasoline tractors embodied many of the same faults: they were still too heavy; they were unreliable and broke down about as often as they ran; and, nearly all of them had an alarming tendency to dig themselves into mud holes in wet soil.

During those early years, designers were convinced that there could be neither power nor traction without great weight. The efforts of all progressive farm tractor manufacturers have since been directed toward lessening a tractor’s weight per horsepower. The early steam giants weighed more than 1,000 pounds [lb] (450 kilograms [kg]) per horsepower. Today’s farm tractor weighs about 95 lb (43 kg) per horsepower.

Gas powered tractors were tested on farms in the early 1900s; however, the first all-purpose gas tractor was not introduced until 1922. It had a high rear wheel drive for maximum clearance under the rear axle, narrow front wheels designed to run between rows, and a power connection to attach other implements on either the front or rear end. This power take-off was standard on all farm tractors by 1934. The use of the power take-off allowed all harvesting machinery to employ a wider cut and high-speed gearing. It meant that rotary power from the engine could be transmitted through a flexible shaft to drive such field implements as mowing machines, balers, combines, etc.

In 1933, pneumatic tires were introduced and, for the first time, allowed tractors to be used on paved highways, a valuable aid in moving equipment from one field to another on farms crossed by paved roads.

The continued development of farm machinery has kept pace with the rapid expansion of technology. The modern farm, for example, can use a single multi-purpose machine for precision tillage, planting, shaping the beds, and fertilizing the soil, all in a single pass. For the farmer who needs to grade his/her field to an exact slope for proper surface irrigation, the farmer can use special laser-leveling equipment. A laser beam is transmitted at the pre-set angle of slope and its signal is received on a mobile scraper. The scraper blade is constantly changing pitch to assure the angle of slope is leveled accurately. With laser leveling, farmers have achieved a 20-30% savings in irrigation water compared with traditional methods.

The use of aircraft in farming has also revolutionized many farming techniques. Fertilizers and pesticides are now widely broadcast over large fields by low-flying crop dusting planes. In some parts of the world, rice is sown over flooded fields by air, which saves a tremendous amount of manual labor traditionally used to plant rice.

Harvesting techniques have also been modernized since the days when McCormick’s reaper was pulled across the fields. Today, almost all small grains are harvested by self-propelled combines that cut the crop, strip it if necessary, and deliver the grain to a waiting bin. Although some corn is harvested and chopped for silage, most is grown for grain. Special harvester heads strip and shell the ears, delivering clean kernels ready for bundling or storage in waiting silos. To ease the burden of handling large hay bales, machines can now harvest a hay crop, compress the hay into compact 1.6 inch square cubes, and unload the compressed feed nuggets into a waiting cart attached to the rear of the harvester.

Harvesting fruits and vegetables has always been the most labor intensive farming operation. Traditionally, harvesters simply cross a field and slice off the head of cabbage, lettuce, or celery with a sharp disk or series of knives. Most of these harvesters are non-selective, and there can be considerable waste from harvesting under- or over-ripe produce. Selection for color or grade is dependent on workers at the site or at grading stations.

Today, special electronic equipment attached to a harvester can determine the correct size, color and density of certain types of produce. Tomatoes, for example, now pass through special harvesters where an optical sensor inspects each tomato as it passes at high speed. The sensor judges whether the tomato is mature or not mature, red or green, and rejects the green fruit. Today, more than 95% of California’s vast tomato crop is harvested mechanically. In addition, tomatoes have been genetically altered for tougher skin, allowing mechanical harvesting.

Asparagus harvesters can determine the pre-set length before cutting, while a lettuce harvester electronically determines which heads meet the proper size and density standards. Yet, despite the tremendous advances in agricultural technology, many fruits and vegetables are still best harvested by hand. These include most citrus fruits, melons, grapes, broccoli, etc.

In dairy farming, modern equipment such as automated milking machines, coolers, clarifiers, separators, and homogenizers has allowed the farmer to increase his/her herds as well as the productivity of the cattle. Yet the dairy farmer still puts in more labor-hours of labor per dollar return than does the field-crop farmer. According to a study by the U.S. Department of Agriculture, the average number of labor-hours used to produce an acre of corn in a Midwestern state was reduced from 19.5 in 1910 to 10.3 in 1938 and to less than seven in 1995. That amount has stayed about the same in the mid-2000s. In contrast, no change was reported in the labor-hours required in the production of beef cattle and egg-laying hens, while a 5% increase was noted in the labor associated with dairy farming.

In the twenty-first century, farmers hook up their agricultural machines to sensors that are connected to computers in order to measure operational characteristics. The computer evaluates whether there is a fault with the machine. If a problem is found, the computer can locate the trouble, recommend repair measures, and provide other helpful information. Oftentimes, the computer can directly relay the information to a distant control station if additional help is needed. Farmers also use satellites in space to determine the best time to plant, when and where to apply disease and insect control products, whether enough moisture is getting to the crops, and many other methods to improve crop productivity and quality.

Benedict A. Leerburger