Soil layer models created with profile cone penetrometer data

In creating soil layer models for our study site, we were challenged (i) to express vagueness of our soil data, while at the same time maintaining adh erence to systematic classification principles, and (ii) to describe contin uously the spatial distribution of soil materials and layers in three dimen sions. We developed a method to create 3-dimensional (3-D) continuous soil layer models describing the distribution of soil materials, reworked loess vs. glacial till. Soil attribute data such as texture, bulk density and wat er content, in combination with penetration resistance obtained with a prof ile cone penetrometer on a 10-m arid, were used to describe soil materials and layers. We compared crisp hierarchical clustering with fuzzy k-mean cla ssification in creating soil layer models for a 2.73-ha site in southern Wi sconsin. The continuous 3-D soil layer models were developed using horizont al ordinary kriging and vertical linear interpolation. Validation proved th at the crisp 3-D soil layer model predicted soil layers more accurately tha n the fuzzy 3-D soil layer model. We conclude that at the working scale, th e crisp classification is superior to the fuzzy classification. (C) 2001 El sevier Science B.V. All rights reserved.