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background    feedstocks    processes    products

Row cropping is a major Wisconsin industry, where over six million acres are used to make products ranging from grains to legumes. The top crops in the state include corn, soybeans, potatoes, oats, winter wheat, barley and sweet corn. Perennial grasses such as alfalfa are also important, and analysts speculate that the industry might benefit from the inclusion of crops currently uncommon to Wisconsin, such as canola or switchgrass.

Each of these crops requires its own methods of management, but they all roughly follow a similar pattern:

• Preparing the field for planting, which may include tilling
• Planting the crop
• Tending to the crop during the growing season, which may include weed and pest control and fertilizing
• Harvesting the crop, which is usually done with large machines. This step often leaves behind crop residues, such as the stalk in corn harvesting. This plant matter is usually left in the field to augment fertility, promote soil structure and prevent soil erosion.
• Possible direct marketing, as in the case of sweet corn
• Transporting crop, such as to a grain elevator
• Milling, processing or pressing, as necessary
• Transportation of the final product

Many of these crops do very well when incorporated into a crop rotation, as this reduces farmers' need for supplemental chemicals and breaks up the life cycles of pests and diseases. Cultivation of fruit crops such as apples and cherries is similar and begins with the tending step listed above. Harvesting is usually done by hand.

Once out of the field, many fruits and vegetables are further processed for human consumption. Processing refers to preservative activities, such as canning, performed on produce to prepare them for transport and sometimes alter their flavor.

Each fruit and vegetable must be handled somewhat differently. While many steps are fundamentally similar, they are not always performed in the same order, and some are performed only for fruit or only for vegetables. Major steps include:

• Cleaning and sorting to remove damaged or immature pieces
• Peeling, either by mechanical means, by using steam to loosen the peel for mechanical removal, or by soaking the produce with a heated lye solution, which is then washed away along with the peel
• Fractionation, including coring, which separates desirable parts from undesirable pomace, and slicing, which divides the desirable portion into smaller pieces
• Blanching, in which the produce is flash-heated
• Cooking to alter the texture and flavor of the produce
• Can filling, which often includes the addition of juice, puree, salt, sugar or other preservatives
• Can sealing under pressurized heating

For fruits, the typical process is cleaning and sorting, peeling, fractionation, can filling and can sealing. Cooking only occasionally occurs before can filling, as with cherries. For vegetables, the typical process is cleaning and sorting, fractionation, blanching and/or cooking, peeling, can filling and can sealing.

• Alfalfa
• Barley
• Corn (field grain)
• Corn (sweet grain)
• Corn stover
• Crop residues
• Forage grasses
• Oats
• Pomace, scraps & spoilage (peels, pulp and cores)
• Potatoes
• Rapeseed (canola)
• Soybeans
• Sugar crops
• Switchgrass
• Wastewater (fruit & vegetable processing)
• Winter wheat

• Aerobic digestion/composting
• Anaerobic digestion
• Biomass gasification
• Combustion
• Dry mill corn processing
• Esterification/transesterification
• Fast pyrolysis
• Fermentation of 6-carbon sugars and starches
• Fermentation of lignocellulosic biomass
• Fiber composites manufacturing
• Lipid extraction
• Thermochemical liquefaction
• Wet mill corn processing

• 1,3-Propanediol (PDO)
• 3-Hydroxypropionic acid (3-HP)
• Acetic (ethanoic) acid
• Anaerobic digestion effluent
• Biobased fuel gas & syngas
• Bio-derived liquefaction oil
• Biodiesel
• Biogas
• Brewers yeast
• Butanol
• Char
• Corn gluten feed
• Corn oil
• Corn syrup
• Crop fibers
• Distillers' dried grains with solubles
• Durable building materials
• Ethanol
• Fertilizer
• Full-fat flour
• Glass aggregate
• Glycerin
• High-fructose corn syrup
• Itaconic acid
• Lactic acid
• PHA (Polyhydroxyalkanoate) polymers
• Pyrolytic bio-oil
• Soybean meal
• Specialty chemicals
• Succinic acid
• Volatile gases (energy)

Emission Factors. 1995. 9.8.1: Canned Fruits And Vegetables . US Environmental Protection Agency. August 1995. (13 May 2004)