Application of Spatial Statistical Methods to the Study of Soil Fertility Pattern
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Date
2000-06
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Addis Ababa,University
Abstract
Adequate characterization of soil heterogeneicy' of an experimental site is a good
gu,id e and at times even a prerequisite to choose a good experimentation technique.
Based on data from a uniformity trial on wheat, soil fertility pattern of an experimental
farm was studied using the techniques of uniformity trials and spatial autocorrelation
analysis.
From the soil productivity contour map, a uni-directional fertility gradient (from left to
right) was observed on fields using broadcast sowing method than using row
plantation method. The same result was a/so confirmed using the mean square
between stripes method. The distribution of fertile plots was found to be relatively
heterogeneous for row planted fields than for broadcast sown fields. The degree of
adjacent plot correlation between yield of plots using broadcast sowing method was
relatively higher than for row plantation method as measured by Smith 's coefficient of
heterogeneity indicating that the variability in yield due to any given plot size does
also depend on crop geometry (type of plantation method). Both square and
rectangular plots were equally efficient in reducing the error variance. A plot size of 8
to 12 m2 was found to be optimum on both plantation methods.
The Moran's, I, and Geary's, c, coefficients were used to test against spatial
autocorrelation between yields of neighbOring experimental plots. For all the three
cases considered to represent 'neighborhood' between plots, namely, Bishop's case,
Rook's case and Queen's case, both tests confirmed that there is a significant spatial
autocorrelation between neighboring plots using broadcast sowing method. For row
planted fields, the observed spatial autocorrelation became insignificant for a plot
size 30 m2 with bishop's case, 4 m2 with rook's case (using Moran's I), and 12 m2
with queens case (using Moran 's I).
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Keywords
Application of Spatial Statistical Methods