Apparent soil electrical conductivity (EC a ) has shown promise as a soil survey tool in the Midwestern United States, with a share of this interest coming from the precision agriculture community. To fully utilize the potential of EC a to map soils, a better understanding of temporal changes in EC a is needed. Therefore, this study was undertaken to compare temporal changes in soil EC a between different soils, to investigate the influence of changes in soil water content on soil EC a , and to explore the impacts these EC a changes might have on soil mapping applications. To this end, a 90 m long transect was established. Soil EC a readings were taken in the vertical and horizontal dipoles at five points once every one to two weeks from June until October in 1999 and 2000. At the same time, soil samples were collected to a depth of 0.9 m for volumetric soil water content analysis. Soil EC a readings were compared to soil water content. At four of the five sites linear regression analysis yielded r 2 values of 0.70 or higher. Regression line slopes tended to be greater in lower landscape positions indicating greater EC a changes with a given change in soil water content. Two of the soils had an EC a relationship that changed as the soils became dry. This is an item of concern if EC a is to be used in soil mapping. Results indicated that soil water content has a strong influence on the EC a of these soils, and that EC a has its greatest potential to differentiate between soils when the soils are moist. Soil water content is an important variable to know when

Probabilistic discrete choice experiments are frequently applied in strategic policy, management, and marketing problems to model and predict consumer choice behavior. The authors consider the construction of a class of discrete choice set experiment designs for estimating all availability and attribute cross effects where there are m brands and one attribute for each brand.

Reclamation is performed on disturbed lands to return the land to productivity as rapidly as possible. From the perspective of the pedologist, the ultimate in reclamation would be to return the soil resource to its previous condition as rapidly as possible, but do reclamation methods increase rates of pedogenesis? To investigate this question, studies that report rates of soil formation in both reclaimed and natural sites were gathered from the literature, and depth of soil formation was plotted against years of pedogenesis. The slopes and y‐intercept elevations of logarithmic regression trend lines were statistically compared to determine if rates of pedogenesis were the same in reclaimed and naturally forming soils. Results of the analysis indicate that rates of pedogenesis in reclaimed soils are not higher than in natural soils; however, soil amendments used during the reclamation process likely create parent material conditions that are ideal to support vegetative growth and start reclamation pedogenesis at an advanced stage.

No abstract

We examined the ontogeny of individual distinctiveness in time-allocation patterns of black-tailed prairie dogs (Cynomys ludovicianus). All adults and yearlings (n = 112) in the study colony were observed in 14 separate samples, beginning in early April and ending in mid-August. Pups (young of the year, n = 105) were observed in the last 11 of these samples, beginning with their first emergence above ground in late May to early June. Discriminability was determined using a Monte Carlo procedure that randomly selected data from 20 individuals; these data were then entered into a discriminant analysis and this procedure was repeated 100 times. The percent correct classification from these runs was averaged to produce a mean discriminability score. We found that (i) overall, individual pups were discriminable at levels three times higher than that expected by chance alone, (ii) pup discriminability declined significantly over the summer and yearlings had lower discriminability scores than did pups, (iii) average discriminability increased from yearlings to adults and adult values were significantly higher than those for pups, (iv) with the exception of mothers (who had the lowest discriminability values of any group tested), all sex and parental groups of older prairie dogs were significantly more discriminable than were pups, (v) distinctiveness among pups did not appear to be a result of differences between litters, and (vi) measures of behavioral bout lengths proved no better at discriminating individuals than time budgets. The results indicate that the ontogeny of individuality in prairie dog time budgets is not a simple linear function and that discriminability may be constrained by a number of contextual influences.