Document Type
Article
Publication Date
11-1999
Abstract
To determine temporal changes in soil nutrient status, reproducible results must be obtained at each time step. The objective of this paper was to determine the impact of grid distance on the reproducibility of spatial variability measurements. Soil samples from the 0 to 15 cm depth were collected from a 30 by 30 m grid in May 1995 in a 65 ha notill corn (Zea mays L.) field. Each bulk sample contained 15 individual cores, collected at sample points located every 11.4 cm along a transect that transversed 3 corn rows (57 cm). At each sampling point latitude, longitude, elevation, landscape position, and soil series were determined. The 30 m grid was used to develop 4 and 9 independent data sets having a 60 and 90 m, grids, respectively. Semivariograms, nugget to sill ratios, and mean squared errors were calculated for each data set. At 60 m: (i) the total N, total C, and pH semivariograms, of different start points, were similar, while semivariograms for Olsen P, K, and Zn were different; (ii) the spatial dependence ratings, based on the nugget to sill ratio, for total N, total C, and pH semivariograms were consistent and suggested moderate spatial dependence; (iii) the spatial dependence rating for Olsen P, K, and Zn for the 4 semivariograms were not consistent and ranged from weak to moderate spatial dependence. At 90 m all soil nutrients had different semivariograms for each start point, while the spatial dependence rating for each total N, total C, and pH start point were consistent and showed moderate spatial dependence. The total C, P, K, Zn, and pH MSE values at 60 m, were 30, 30, 41, 28, and 72% lower than the variance, respectively. This study showed that semivariogram, semivariance, MSE, and nugget to sill ratios reproducibility were dependent on soil nutrient and grid distance.
Publication Title
Precision Agriculture
Volume
1
Issue
3
First Page
277
Last Page
289
Format
application/pdf
Language
en
DOI of Published Version
10.1023/A:1009921024451
Publisher
Kluwer Academic Publishers
Rights
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S.
Recommended Citation
Chang, Jiyul; Clay, David E.; Carlson, C. Greg; Malo, Douglas D.; Clay, Sharon A.; Lee, John; and Ellsbury, Mike, "Precision Farming Protocols: Part 1. Grid Distance and Soil Nutrient Impact on the Reproducibility of Spatial Variability Measurements" (1999). Agronomy, Horticulture and Plant Science Faculty Publications. 233.
https://openprairie.sdstate.edu/plant_faculty_pubs/233