ABSTRACT
Summer fallow has been a controversial practice in many semiarid regions of the United States and Canada. Crop production in these regions has been limited by low and variable precipitation. Summer fallow has been practiced to increase the water available for succeeding crops in regions that receive less than 500mm of precipitation.[1] The basic objectives of summer fallow are: 1) maximize soil water storage; 2) make plant nutrients available; 3) reduce soil erosion hazards; 4) minimize energy and economic inputs; 5) control weeds during the entire fallow period; 6) take advantage of standing stubble to capture snow; and 7) suppress soil water evaporation during the warm season.[2]
Summer fallow was adopted in the semiarid regions following the dust bowl era of the 1930s in the United States. Since then; considerable changes in equipment and technology have taken place. Summer fallow discussions in this article will focus primarily on the semiarid Great Plains of the United States and Prairie Provinces of Canada. Statements about the semiarid Pacific Northwest will be included. Two major summer fallow systems discussed will be winter wheatfallow and spring wheat-fallow. Fallow will be divided into seasonal fallow segments that consist of afterharvest (harvest though October), over-winter (November through April), summer fallow (May through October, or until seeding winter wheat), and second over-winter for spring wheat (November until spring wheat seeding). Summer fallow segment for this paper will be defined as a practice where no crop was grown and all plant growth was controlled with herbicides or cultivation during the season when a crop would normally be grown.
