Soil bulk density estimation for tillage systems and soil textures

Soil bulk density ( .b) is a physical property related to many phenomena, such as plant root development and solute transport in soils. In this study, a comprehensive data search of literature from 1980 to 1997 was made to examine .b as influenced by soil organic matter (OM), soil texture, primary tillage and secondary tillage practices and tillage depth. The literature data showed that .b is principally related to clay content and OM for no-till soils, while any soil textural variable and OM can be predictors of .b for tilled soil conditions, depending on primary tillage types and soil strata. Based on the literature data, regression models that incorporate tillage effects were proposed to estimate .b for nine tillage types, including no-tillage. The models predict .b for a given tillage condition by estimating the bulk density of soil for no-tillage ( .NT) and adding a change in density ( ..) induced by tillage which depends on tillage type used and the tillage depth. Model results for three common tillage types (moldboard plow, chisel, and no-tillage) were validated with field data from Quebec, Canada and good agreements in .b values between the field data and the model results were obtained. Model inputs are soil textural variables and OM. Thus, the model is widely applicable, and can be coupled into other studies, such as those of soil erosion, soil compaction, tillage evaluation, crop growth or soil water and solute transport.