Crop Production Systems

Of the seven crops listed, six are annual crops that must be replanted each year (only hay crops would be left in place from year to year). The process of cultivating crops typically begins with tillage of the soil. Although tillage can serve a number of functions within a crop production system, the most fundamental function is to create conditions that will ensure good contact between seed and soil at the time of seed planting and the ready availability of water to the seed during germination. The degree to which the soil is disturbed by tillage prior to seed planting provides a means of categorizing crop production within a range of tillage systems. These systems range from no-tillage in which there is not soil disturbance in a field except during the process of planting a crop to conventional tillage in which multiple tillage operations can extend over many months and take place before, during, and after planting. Crop production systems that involve pre-plant tillage but maintain residues from a previous crop on the soil surface are referred to as conservation tillage practices.

For the major row crops produced in the United States, farmers use a range of production practices. Conventional tillage (also known as intensive tillage) usually involves a series of field operations that result in a residue-free soil surface at the time a crop is planted. Conventional tillage systems developed in this country to take advantages of the following benefits:

• Creation of a seedbed or root bed
• Control of weeds or the removal of unwanted crop plants
• Incorporation of plant residues into the soil profile
• Incorporation of fertilizers and/or soil-applied pesticides
• Establishment of specific soil surface configurations for planting, irrigating, drainage, and/or harvesting operations

The major disadvantage of conventional tillage is the susceptibility of "unprotected" soil to erosion by water or by wind. Tillage is also energy-intensive, requiring large inputs of machine work and numerous trips across a field during a single growing season. Conventional tillage was "standard operating procedure" in the era before effective chemical weed and pest control strategies were available to farmers.

Concerns about soil erosion led to the development of crop production strategies that retained crop residues on the soil surface. Conservation tillage requires more sophisticated implements that are capable of producing a seedbed while leaving a portion of surface residues undisturbed. Reduced tillage usually leaves 15% to 30% residue coverage on the soil surface. True conservation tillage is any tillage method that leaves at least 30% residue coverage on the soil after a crop has been planted. It can be accomplished through no-till, strip-till, ridge-till, or mulch till practices.

Organic Farming

Organic farming is a small, but growing, segment of U.S. agriculture. USDA estimates the value of retail sales of organic foods at $6 billion in 1999 with about 12,200 organic farmers nationwide, most with small-scale operations. Organic farming encompasses both crop and animal production and is defined as "ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity."

'Organic' is a labeling term that denotes products produced under the authority of the U.S. Organic Foods Production Act. "The principal guidelines are to use materials and practices that enhance the ecological balance of natural systems. Organic agriculture practices do not ensure that products are completely free of residues; however, methods must be used to minimize contamination." Organic food handlers, processors and retailers must adhere to standards that maintain the integrity of organic agricultural products. This includes practices such as minimizing or eliminating the use of herbicides in crop production and antibiotics in animal production.

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