ABSTRACT
Water limits crop production in most agricultural soils and directly or indirectly affects soil physical, chemical, and biological properties and processes. Quantity of water held in soil is commonly determined by measuring the mass of water relative to the mass of dry soil. The ratio is called gravimetric soil water,[1,2]
oven-dry,[2,3] or soil water content.[3] This measurement has been a mainstay of many field studies and is generally accepted as a calibration standard for many indirect soil water measurement methods.[2]
A brief sampling of literature from 1907 to 1930 (Agronomy Journal, American Society of Agronomy) revealed that scientists then, as now, rarely provide detail on methodology used to measure soil water content. Often the reader was left to assume that an investigator followed expected procedure. For example, reports from the early 1900s might state that ‘‘moisture was determined in the usual way;’’[4] or ‘‘samples of soil for moisture determination were taken;’’[5] or ‘‘oven-drymethod’’ was used;[6] or soil was dried ‘‘to constant weight at the temperature of boiling water.’’[7] Davisson and Sivaslian[8]
provided standards for scientists of that era with a review of important findings in the German literature.
