Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/9/2005
Publication Date: 11/15/2005
Citation: Jabro, J.D., Stevens, W.B., Evans, R.G. 2005. Spatial variability of physical properties in lihen sandy loam soils. In: Agronomy Abstracts. ASA-CSSA-SSSA International Annual Meetings, November 6-10, 2005, Salt Lake City, Utah. CD-ROM.
Technical Abstract: Knowledge of the spatial variability of soil physical properties is important for precision agriculture. The spatial variation of soil bulk density, cone index, and gravimetric water content in a loamy sand soil was assessed using several geostatistical techniques and traditional statistics. Field data from a research farm located near Williston, ND was used to evaluate the variability of bulk density, cone index, and water content and to determine whether they were correlated with each other. Soil bulk density was determined from samples collected using a core soil sampler while cone index was measured by inserting a hand-held digital penetrometer into the soil at three different locations within a 30-cm radius of where the bulk density samples were extracted. The measurements were made on a 16 m x 36 m grid sampling system, which created 72 individual grid cells. Soil properties were measured at the center of each grid cell at depths of 5-10 and 20-25 cm. The three soil parameters were modeled as normally distributed random variables. Sample coefficients of variation were smallest for bulk density and largest for cone index; a significant correlation was identified between bulk density and cone index at both depths. Further, a weak correlation was found between cone index and water content. Sample semivariograms were also constructed for each soil property and were described by combinations of pure nugget and spherical model structures.