SIGNIFICANCE OF GRAVIMETRIC VERSUS VOLUMETRIC MEASUREMENTS OF SOIL QUALITY UNDER BIODYNAMIC, CONVENTIONAL, AND CONTINUOUS GRASS MANAGEMENT

We analyzed 22 physical biological and chemical soil properties using adjacent fields from commercial farms in New Zealand. Our objective ru ns to measure the effects of biodynamic, conventional and continuous g rass systems on soil quality. One set of three adjacent farm fields in cluded a biodynamic vegetable field, a conventional vegetable field, a nd a biodynamic pasture field. A second set of three adjacent farm fie lds included a biodynamic mixed (grain/sheep/beef) field, a convention al mixed field, and a biodynamic pasture field. The pasture fields had soils of higher biological quality (i.e., more organic matter microbi al activity and earthworms) than the soils of the biodynamically or co nventionally cropped fields. The biodynamic vegetable field had soil o f higher physical biological and chemical quality than its conventiona l neighbor. When converting the chemical and biological data from a ma ss to a volume basis, most statistically significant differences remai ned in the vegetable/pasture data set, whereas many became nonsignific ant in the mixed/pasture data set. Presenting data on a volume basis p er unit given surface depth (like 0 to 10 cm in this study) may penali ze a farm with lower bulk densities and thicker topsoils in comparison to an adjacent farm with higher bulk densities and thinner topsoils. We recommend calculating soil measurements an a volume basis per unit of topsoil depth (complete A horizon) or per unit of solum depth (A an d B horizons). Whether data are presented on a mass or volume basis, b iological or ecological significance should be emphasized rather than statistical significance.