Frequency distributions and spatially dependent variability of ammonium and nitrate concentrations in soil under grazed and ungrazed grassland

Spatial Variability Patterns of Wheat Growth and Soil Properties in a Small Field as Affected by Tillage Intensity

“…A comparison of the spatial variability of soil nutrients on two scales, 0.25 and 3.3 ha, showed that nitrate had the shortest range ( < 5 m) , soil organic carbon the longest (>180m), and phosphate an intermediate range (Cahn et al, 1994). In some studies, nitrate exhibited no spatial dependence for distances larger than the minimum sampling distance, which was 30 m in an Alfisol field for cereals and sugarbeet (Dahiya et al, 1985) or 0.4 m in grassland (White et al, 1987). Spatial variability of soil and crop parameters is influenced by time and by soil management.…”

Spatial variability of soil nitrate nitrogen after potatoes and its change during winter

“…This suggests that, due to a homogenization of the soil NO 3-N concentration, as indicated by the increasing range of spatial dependence, a shift to a normal frequency distribution took place towards the end of the winter. An uneven spreading of N fertilization is most likely responsible for the skewness of the soil NO3-N content (White et al, 1987).…”

“…White et al (1987) found only scarce evidence for strong spatial dependence of soil NO 3 -N over distances > lm. However, Tabor et al (1985) describe such a dependence over 150m.…”

“…Soil NO3-N frequency distributions have been described as normal (Dahiya et al, 1984), or more commonly as lognormal (Cameron and Wild, 1984;Tabor et al, 1985). In a several years' investment of soil NO3-N under grassland, White et al (1987) found predominantly a lognormal frequency distribution, irrespective of time of year or depth.…”

Quality measures for soil surveys by lognormal kriging

“…It is commonly found that soil and other geochemical variables do not appear to be normally distributed (White et al, 1987;Allègre and Lewin, 1995). This is best judged by exploratory statistics, such as the coefficient of skewness, and histograms of the data (Webster and Oliver, 2007).…”