Submitted to: European Journal of Plant Pathology
Publication Type: Abstract Only
Publication Acceptance Date: 7/2/1995
Publication Date: N/A
Technical Abstract: Summerfallowing is practiced on two million hectares of semi-arid winter wheat in northwest U.S.A. Fallowing begins after wheat harvest in July and extends until winter wheat is seeded 15 months later. Detrimental aspects of fallow include increased soil erosion from wind and water, declining soil organic matter, lower microbial biomass, and loss of crop production during the fallow period. Fallowing persists because it conserves soil moisture for autumn planting, stabilizes wheat yields over seasons, and mitigates damage from diseases and weeds. Societal concerns about soil erosion and declining soil quality have stimulated research to minimize or eliminate fallow. Long- term studies show that severity of wheat diseases are less in a wheat/pea than a wheat/fallow rotation or annual wheat. Tillage that leaves high amounts of crop residue on the soil surface increases potential damage from soil-borne root diseases and grassy weeds. Tillage and nitrogen practices influence soil organic matter content, microbial biomass, soil pH, and distribution of crop residues and weed seeds. Disease and weed prevalence increase as the rate of N applied increases.