Machinery

An acre of land requires at least 9 major purchases from the local John Deere equipment dealer, Northfield Tractor and Equipment: 2 tractors, a corn planter, a ripper, a field cultivator, a stalk shredder, and a combine fitted with a corn head and platform.

John Deere 8320 Tractor (Purchase #1)
       ° Two passes across the land
       ° 1.9 gallons of diesel fuel
      
This tractor pulls a John Deere 5 shank 2700 ripper (purchase #2), which is used in the fall to bury crop residue from the previous summer. It also pulls a John Deere 980 field cultivator (that's #3) in the spring, which levels the ground and incorporates any remaining residue from the previous fall. This tractor will use about  9.5 gallons of diesel fuel per hour of usage (Estrem) and weighs 21,050 pounds (John Deere "170- to 225").  Plowing at a rate of about 10 acres per hour, one acre requires 0.95 gallons of fuel in the fall and 0.95 gallons again in the spring (Legvold). Luckily, the fuel tank holds 135 gallons, enough for one days work (Estrem). 

John Deere 7720 Tractor (#4)
     ° Two passes across the land
     ° 1.5 gallons of diesel fuel

This tractor pulls the corn planter, a John Deere 1760 narrow 12 row planter (#5).  The planter is equipped with three yellow bins for each row. One holds seed, one holds fertilizer, and one holds insecticide. All are incorporated into the ground in one pass over the land. This tractor will also pull a John Deere 120 Drawn Flail Shredder (#6), to shred the crop residue after harvest in the fall. This tractor gets 16.25 horsepower hours/gallon and 8.46 gallons per hour of usage (Estrem). This comes to about 0.75 gallons per acre when pulling the corn planter (Legvold).

This picture is of a John Deere 4605 tractor, similar to the 7720 in horsepower and size, and a detail of the corn planter, showing the bins used for seed, fertilizer, and insecticide.

John Deere 9560 Combine (#7)
     ° One pass over the land
     ° 0.95 gallons of diesel fuel

Combines are used for harvesting. The combine must be fitted with a John Deere 693 corn head (#8), which harvests 6 rows at a time. The farmer must also purchase a John Deere 624F rigid platform (#9). Together, this unit will pass over the land one time and cut the corn, remove the kernels from the cob, and spit the residue back on the field. The combine has the same engine as the 8320 tractor, therefore it has similar fuel requirements. 

Production
All the John Deere tractors needed for the acre are made in Waterloo, Iowa at John Deere Waterloo Operations, 187 miles south of Northfield. (The combine is made is Rock Island, IL at another manufacturing facility.) Waterloo operations employs over 5,000 men and women in the design and manufacture of the tractors (John Deere "Build"). Manufacturing is split between 6 locations in Waterloo, with a total of 183.9 acres of manufacturing floor space (John Deere "Build"). More than 17,000 parts come together at assembly operations to make a tractor (John Deere "Build").

At the Foundry Operations, molten metal is poured into sand molds to form the castings, engine blocks, transmissions, and wheel castings (John Deere "Build"). Steel, the metal used to make tractor bodies and engines, is an alloy of iron and carbon and is produced from iron ore, limestone, and coke. These three materials are blasted in a furnace to make molten iron, this first step in steel production.  According to the International Iron and Steel Institute (IISI), in 2002 the United States imported more than 30.2 million tons of steel. Operations are not always far from home, however. Two thirds of the iron ore pellets used to make steel in the US come from Minnesota (Iron Mining Association of Minnesota (IMA)). There are six mining companies in Minnesota, employing over 4,000 people (IMA).  Rock containing iron is blasted out of open pit mines in northern Minnesota. It is broken and crushed so that the iron can be separated.  After the iron ore is separated from the rest of the rock, small pellets are formed for transport to steel mills in places like Gary, Indiana. At the steel mill the ore pellets are mixed with coke (pure carbon) from West Virginia and limestone from Indiana (Ryan and Durning 37). Oxygen is then blasted through the iron to removed impurities (Ryan and Durning 38). Stuff reports that "According to the EPA's Toxic Release Inventory, U.S. steelmakers generated 650,000tons of hazardous waste in 1993, more than any other industry" (37).  Though steel requires lots of raw materials to produce it is easily recycled and of the 960 million tons of steel produced worldwide in 2003, more than 60% of it was produced from recycled steel (IISI).

Fuel
     ° 3.6 gallons total
     ° 136,000 kcal used in production

In total, the farm machinery will use 3.6 gallons of fuel when passing over our 1 acre plot. It takes 10,000 kcal to produce one liter of diesel fuel (Gregory 48) therefore 136,000 kcal of energy were put into the production of the 3.6 gallons. This is enough energy to run a 40 watt light bulb for 164 days straight!
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Chemicals: 

Insecticide
Root worm insecticide is applied by the corn planter at the time of planting. The active ingredient  is called terbufos (Fig. 1), an organophosphate (OP). All OPs are neurotoxins, and terbufos is one of the most acutely toxic OPs (EPA "Overview"). Terbufos is toxic to insects, birds, mammals, and fish. The maximum use rate is 1.3 lb. of terbufos per acre (EPA "Overview"). Terbufos is considered moderately mobile, meaning that it can wash into streams or seep into ground water. It degrades rapidly to terbufos sulfoxide and terbufos sulfone, which are more mobile and persistent then parent terbufos and equally as toxic (EPA "Overview"). 

Fertilizer
Two types of fertilizer are used.  Anhydrous ammonia (NH₃) is a gas and must be applied by Cannon Valley Cooperative. They will apply 90 lbs/acre.  In addition, 220 lbs/acre of 9:23:30 (Nitrogen:Phosphorus:Potassium ratio) fertilizer is applied.

Nitrogen (N) exists abundantly in the atmosphere as a gas. To fix nitrogen (convert it from N₂ gas to liquid ammonia)  high voltage must be used. Then, ammonia must be converted to  urea or ammonium nitrate for use as fertilizer. The location of nitrogen fixing plants in the US has been dictated by the abundance of natural gas (used as an energy source for fixing).  In 1997, the midwest produced 16% of the total US ammonia production (Rabchevsky 118). However, increasing natural gas prices in the US have been causing an increase in N fertilizer imports from countries such as Trinidad and Tobago, Canada, and Russia (Rabchevsky 119).

Phosphorus (P)  is added to soil as the orthophosphate anions H₂PO₄ ^- and HPO₄^2-.  It originates in phosphate rock reserves found around the US (The Fertilizer Institute (TFI)). The largest phosphate facility in the world (composed of 22,000 acres) is located in Beaufort County, North Carolina and owned by PotashCorps. PotashCorps removes roughly 30 meters of earth from their open pit mines before reaching the phosphorus  ore.  The ore is mixed with water and transported to the mill by an ore slurry pumping system. There, coarse materials, clays and sand are removed.

Potassium is provided by potash (potassium carbonate). The US imports almost all of our potash from places such as Canada  (TFI). Potash reserves exist today where ancient sea beds have evaporated and left behind potassium salts (KCl). PotashCorps also mines potash in an area like this west of Lake Winnipeg in Saskatchewan, Canada. Potassium salts must be separated from other salts before they can be used on the field.

Fertilizers consume vast amounts of energy in production, particularly nitrogen fertilizers. Production sites, which are dictated by resource availability, are often thousands of miles away from the Cannon River region. Total fertilizer for one acre will consume 1,194,038 kcal of energy to produce (Gregory 48).

Herbicide
Roundup® herbicide, produced by Monsanto, is put on at the end of June (26oz/acre). Some farmers will apply their own Roundup®. These farmers must buy additional equipment. Others will hire Cannon Valley Cooperative to apply the Round-up. It is applied as a foam, which is easy to see on application and never becomes airborne, reducing volatilization.

The active ingredient in Roundup® is glyphosate. Glyphosate herbicides produced by Monsanto are the most widely used type of herbicide in the world. In recent years, it has been applied on 13-20 million acres of land (EPA "glyphosate"). It interferes with a plant enzyme (called EPSP synthase) that is crucial for aromatic amino acid synthesis. Without the ability to produce aromatic amino acids, the plant dies (Alibhai and Stallings 2001). Humans and other animals do not have this enzyme and are therefore unaffected by glyphosate. This compound is degraded by microbes and fungi in the soil after application into aminomethylphosphonic acid (Monsanto "fate"). It takes 32 days for half of the applied Roundup® to degrade, and  six months for 90% to be degraded (Monsanto "fate").  The  maximum  Contaminant Level in water, set by the US Environmental Protection Agency,  is  0.7 parts per million (EPA "glyphosate").

It takes 57,000 kcal of energy to produce 1 kg of glyphosate (Gregory 48).  Twenty six ounces, applied to one acre, will have consumed  roughly 42,000 kcal.
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Seed

With one seed every 6.5 inches, in rows 30 inches apart, a farmer will plant 30,000 seed corn per acre.

The seed is purchased from Monsanto and is known as Roundup Ready® corn. It is  0.019 cents per seed so one acre will cost $59.25 to plant (Legvold). These seeds contain the Roundup Ready® gene, which makes each plant resistant to glyphosate, a general  herbicide. Individual corn plants with the Roundup Ready® gene are grown at one of the many Monsanto facilities in the midwest. A researcher hand picks the "most pure" plant for production of a breeder seed, which is distributed to seed growers. The seed growers are farmers who contract with Monsanto.  After harvest, the farmer will ship the seeds back to the production plants for further processing and packaging. Since 1999, Monsanto has invested more than $100 million in North American corn and soybean seed production plants (Monsanto "Seed Production"). Farmers in the Northfield area can buy seeds online from Monsanto.com. They will be shipped through the US Postal Service to their farm.
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Natural Inputs

We cannot forget that there are non-human inputs that are vital to the success of the  acre of corn. Microbes and fungus decompose the dead organic matter, releasing nutrients back into the soil. They also break down the Roundup® applied to the field.  Invertebrates, such as earthworms, consume the crop residue and help redistribute  nutrients in the soil. In a study done in the Cannon River Area, however, no macro invertebrates were found in conventionally farmed fields (Gregory 18). Rain is another essential component. Total annual precipitation for Rice County is about 31 inches (USGS). Most farmers in the Cannon River region do not irrigate. In fact, tiling must be put in place under low areas to keep the land dry.
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Post Harvest

Because farm products do not stay on the farm, a brief description of post harvest practices will be presented. An average yield for one acres of corn is 50 bushels or  2800 pounds (1 bushel = 56 lb.).  All of this corn is stored at the farm and dried to a maximum moisture of 15% using a corn dryer. The drier blows hot air up through the corn kernels until they reach 17.5% moisture content. The corn is then conveyed by a belt back up to the storage bins to cool and continue drying to the desired 15% moisture content.

The drier uses 3,000 gallons of liquefied petroleum (LP) gas in a season, averaging 4 gallons per bushel. LP gas is made  of propane and butane and is one of the by-products of oil refining. Emissions from burning LP gas include particulate matter, sulfur dioxide, carbon monoxide, carbon dioxide, nitrous oxides, and methane (EPA "Residential").

The corn is sold by the truck load year round to the Cannon Valley Cooperative. Cannon Valley Cooperative sells the corn to Bunge or Cargill. The farmer is responsible for hiring a semi truck that will come out to the farm to load up and transport the corn to Bungle or Cargill collection centers. To keep the roads from cracking during melting and freezing processes, full semi truck loads are not allowed on the roads February through April. Therefore, no corn is transported during this time. Collection centers are  located  in places such as  Savage, MN on the Minnesota River. The corn is loaded onto barges and shipped down river. It is used for animal feed, corn syrups, cosmetics, and ethanol (Legvold).
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