1. Potatoes
   Corn
2. Wheat
   Apples

When it comes to American agriculture, corn is king. It represents around $46 billion in annual sales for U.S. farmers, according to the USDA. When combined, corn and soybean sales together represent 43 percent of all income derived from crops.

1. Square mile
   Bushel
2. Acre
   Cubic feet

Most agricultural land in the U.S. is measured in acres. One acre is equal to 4,840 square yards or 43,560 square feet. This type of sizing information is useful for farmers trying to calculate how much livestock or planting their land can support -- and how many hands are needed to tend it.

1. Cattle
   Pigs
2. Chickens
   Goats

Cattle is king when it comes to cash receipts from livestock sales. In fact, cattle represents 38 percent of all livestock sales for American farmers, according to the USDA. Poultry is the next most valuable, followed by dairy cows and then hogs.

1. Throw it away.
   Eat it for dinner.
2. Burn it.
   Feed it to livestock.

Believe it or not, only around 1 percent of all U.S. corn is sweet corn -- the kind you can eat. The rest is called dent corn thanks to its characteristic dented kernels, and can be used as animal feed or in biofuel production.

1. 2.0 to 3.0
   4.0 to 5.0
2. 6.0 to 7.0
   9.0 to 10.0

The acidity of soil, measured by its pH value, has a significant influence on whether crops will crow in that area or not. Levels under 7.0 are considered acidic, while values over 7.0 are seen as alkaline. A pH level between 6.0 and 7.5 is ideal for many common crops, according to the University of Maryland Cooperative Extension.

1. 3 days
   10 days
2. 21 days
   90 days

It takes about 21 days for a chicken egg to hatch, while a turkey egg requires 28 days. This period is known as incubation, and farmers often have to work hard to keep temperature and moisture levels at the proper level to keep eggs viable during this time.

1. Ecology
   Agriforestry
2. Husbandry
   Hydroponics

It might not sound like a scientific term, but husbandry has plenty of science behind it. This practice involves determining the best ways to breed, raise and care for livestock like cattle and goats. Many farmers are experts in this field, either through experience or through extensive schooling.

1. Harvested by hand
   Grows on a tree
2. Harvested mechanically
   Annuals only

In agriculture, row crops are those that are not only planted in rows, but planted in wide enough rows that they can be harvested mechanically using a tractor or other major equipment. Common row crops include potatoes, soybeans, corn and sugar beets.

1. Angus
   Holstein
2. Guernsey
   Jersey

Black Angus beef, which comes from the Angus cattle breed, is heavily marketed and available throughout the U.S. Holsteins, Guernsey and Jersey breeds are primarily dairy cows, and are not typically raised for beef production.

1. Select
   Grade A
2. Premium
   Choice

The USDA rates dairy based on grades. Grade A milk is designed for drinking, while Grade B milk can be used to make cheese, ice cream or other packaged foods.

1. 1
   7
2. 14
   21

Most hens lay around one egg a day -- or every 26 hours to be precise. They generally have a laying life of 3 to 4 years before all egg production stops and the hen is ready to retire.

1. Beef
   Corn
2. Eggs
   Oats

A lot can go wrong between the time a chicken lays an egg and the time that egg makes it to a store shelf. Candling is a process where a bright light is shone over the eggs before they are sold, allowing the farmer to spot any problems -- like eggs that have gone bad for some reason.

1. Apples
   Corn
2. Wheat
   Oats

Annual crops must be replanted each year, as opposed to perennials, which reseed themselves year after year. Most veggies and grains are annuals, while many nuts and fruit -- including apples -- are perennials.

1. Tilling
   Grazing
2. Tractor sizing
   Calculating sales

Livestock spends a lot of time foraging each day, so it's critical that farmers provide enough grazing land to meet the needs of the animals. Animal units are rough estimates of the amount of forage needed for a 1,000-pound cow, who will need 26 pounds of forage a day, on average.

1. Newborn calf of either sex
   Young male cow
2. Really fat old cow
   Young female cow

A heifer by definition is a young female cow -- generally under 3 years old -- who hasn't yet birthed a cow. Once she reaches maturity, she is no longer a heifer and is simply known as a cow.

1. Making a lot of money
   Creating grazing land
2. Stabilizing soil
   Earning subsidies

Cover crops are any plantings designed primarily for soil stabilization. This could mean planting grass or other crops to prevent erosion, or to prevent soil leaching over the season.

1. Sow
   Boar
2. Swine
   Piglet

Pigs are big business in American agriculture, sold to make bacon, chops and other meat products. A sow is a mature female pig, while a boar is a mature male. The term swine can be used for either gender, while a piglet is a younger member of the species which hasn't yet reached maturity.

1. Oats
   Saffron
2. Rice
   Corn

Saffron comes from the stigmas of the crocus flower. It takes 50,000 flowers to produce a single pound of this spice -- which sells for between $5,000 and $10,000. Farmers who live in areas with mild winters need only about a quarter acre of land to produce one pound of saffron.

1. Broiler
   Hen
2. Rooster
   Heifer

Some chickens are raised simply for meat production rather than for egg production. The term broiler describes a young chicken, generally aged between 7 and 14 weeks and weighing 8 to 12 pounds.

1. Meters
   Bushels
2. Grams
   Pounds

Most U.S. crops are measured in bushels, where 1 bushel equals 1 cubic foot, or the equivalent of 8 gallons of liquid. There are around 32 pounds of oats or 56 pounds of corn per bushel.

1. Cows
   Apes
2. Pigs
   Bees

Bees are big business, not only for the honey and wax they produce, but also for their contributions to pollination. Some farms are specialized apiaries with hundreds of hives, while other simply keep a few hives around to produce fresh honey.

1. Interlocking
   Rotation
2. Minimalism
   Combining

Crop rotation is a technique that has been practiced for centuries. It involves planting different crops on a piece of land each season to avoid soil depletion and to maintain the parcel of land for future uses.

1. Crops that grow in your back alley
   Crops that are native
2. Crops planted between rows
   Crops fed to livestock

Alley cropping is a practice that is particular popular in agroforestry -- or tree farming. By planting crops in between rows of trees as they mature, farmers can make extra income and take full advantage of every inch of land.

1. Searching for oil
   Mining
2. Planting seeds
   Raising cattle

Drilling is the process of digging a hole, planting a seed then covering the seed with soil. This is often accomplished using a seed drill attachment on a tractor, but can also be done by hand.

1. Sheep
   Bees
2. Cattle
   Pigs

Ovine means related to sheep, so ovine farmers are essentially raising these woolly critters. Sheep are valuable not only for their soft wool, but also for their meat.

1. Combine
   Head gate
2. Baler
   Fallow

Livestock like cattle require a lot of care. A head gate is a device that holds the animal just behind its head during vet visits, castration, tagging or other tasks. A similar device known as a squeeze chute can also be used to restrain animals on a farm.

1. Beef
   Pork
2. Corn
   Wheat

Checkoff is a program managed by the Cattlemen's Beef Board. Members send the Checkoff program one dollar for every head of cattle sold, and this money is used to market beef. This program is responsible for the slogan "Beef -- It's what's for dinner."

1. Iron
   Calcium
2. Vitamin B
   Potassium

Many substances can be used to fertilize soil, from manure to compost or commercial chemicals. A complete fertilizer provides nitrogen, phosphorous and potassium, which are the three macronutrients needed to fertilize soil.

1. Kill weeds
   Kill bugs
2. Make plants grow faster
   Fertilize soil

A herbicide is designed to keep weeds at bay. Pesticides are similar chemicals designed to kill bugs and other agricultural pests.

1. Strawberries
   Saffron
2. Almonds
   Rice

Commodity crops are those that are traded on the international market, and include things like oats, wheat, rice and corn. Specialty crops include things like fruit, nuts and vegetables.

1. 1
   5
2. 12
   25

Cattle require a lot of land for foraging -- 1.5 to 2 acres per cow per year, according to the USDA. That means a 10-acre farm can sustain only about 5 cows.

1. Barrow
   Deserted
2. Fallow
   Fertilized

Planting crops on the same plot of land every year can strip the soil of nutrients. Leaving it fallow, or unplanted, for a period can keep the soil sustainable, kill weeds and help to conserve moisture.

1. Brain
   Rump
2. Stomach
   Ribs

The USDA measures marbling between the 12th and 13th ribs on a cow when giving the beef a grade. This grade can range from top-of-the-line Prime to lower quality Choice or Select.

1. Traditional
   Conventional
2. GMO
   Tainted

Organic produce is grown without the use of chemical pesticides and fertilizers. Crops grown using more classic methods and tools are labeled conventional.

1. 10 percent
   25 percent
2. 50 percent
   99 percent

Small farms are the norm in the U.S., and 50 percent of all farms bring in less than $10,000 from farm income each year. Despite that, American farming families have a median income of around $75,000 each year, indicating that most farmers also have a job outside of working the farm.