The conventional cropping system,
based on synthetic fertilizer and herbicide use, represented a
typical cash-grain, row-crop farming unit and used a simple
5-year crop rotation (corn, corn, soybeans, corn, soybeans) that
reflects commercial conventional operations in the region and
throughout the Midwest (more than 40 million ha are in
this production system in North America; USDA 2003). Fertilizer
and pesticide applications for corn and soybeans followed
Pennsylvania State University Cooperative Extension
recommendations. Crop residues were left on the surface of
the land to conserve soil and water resources. Thus, during
the growing season, the conventional system had no more exposed soil than in either the organic animal-based or the
organic legume-based systems. However, it did not have cover
crops during the nongrowing season.