index.smith: Uniformity soil. Smith's Index of Soil Heterogeneity

Description Usage Arguments Details Value Author(s) References Examples

View source: R/index.smith.R

Description

Smith's index of soil heterogeneity is used primarily to derive optimum plot size. The index gives a single value as a quantitative measure of soil heterogeneity in an area. Graph CV for plot size and shape.

Usage

1

Arguments

data

dataframe or matrix

PLOT

graphics, TRUE or FALSE

...

Parameters of the plot()

Details

Vx=V(x)/x b

V(x) is the between-plot variance, Vx is the variance per unit area for plot size of x basic unit, and b is the Smith' index of soil heterogeneity.

Value

model

function pattern of uniformity

uniformity

Table of the soil uniformity

Author(s)

Felipe de Mendiburu

References

Statistical Procedures for Agriculture Research. Second Edition. Kwanchai A. Gomez and Arturo A. Gomez. 1976. USA

Examples

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library(agricolae)
data(rice)
#startgraph
table<-index.smith(rice,
 main="Relationship between CV per unit area and plot size",col="red")
#endgraph
uniformity <- data.frame(table$uniformity)
uniformity
# regression variance per unit area an plot size.
model <- lm(Vx ~ I(log(Size)),uniformity)
coeff <- coef(model)
x<-1:max(uniformity$Size)
Vx<- coeff[1]+coeff[2]*log(x)
#startgraph
plot(x,Vx, type="l", col="blue",
 main="Relationship between variance per unit area and plot size")
points(uniformity$Size,uniformity$Vx)
#endgraph

Example output

   Size Width Length plots       Vx   CV
1     1     1      1   648 9044.539 13.0
2     2     1      2   324 7816.068 12.1
3     2     2      1   324 7831.232 12.1
4     3     1      3   216 7347.975 11.7
5     3     3      1   216 7355.216 11.7
6     4     1      4   162 7047.717 11.4
7     4     2      2   162 7123.973 11.5
8     6     1      6   108 6571.278 11.1
9     6     2      3   108 6826.889 11.3
10    6     3      2   108 6812.627 11.3
11    6     6      1   108 6480.927 11.0
12    8     2      4    81 6611.042 11.1
13    9     1      9    72 6276.257 10.8
14    9     3      3    72 6550.445 11.0
15    9     9      1    72 6029.794 10.6
16   12     1     12    54 5769.816 10.4
17   12     2      6    54 6239.270 10.8
18   12     3      4    54 6437.818 10.9
19   12     6      2    54 6199.754 10.7
20   18     1     18    36 4683.748  9.3
21   18     2      9    36 6063.466 10.6
22   18     3      6    36 6074.789 10.6
23   18     6      3    36 5954.826 10.5
24   18     9      2    36 5794.902 10.4
25   24     2     12    27 5558.070 10.2
26   24     6      4    27 5904.217 10.5
27   27     3      9    24 5943.106 10.5
28   27     9      3    24 5571.450 10.2
29   36     2     18    18 4552.791  9.2
30   36     3     12    18 5452.777 10.1
31   36     6      6    18 5662.243 10.3
32   36     9      4    18 5537.279 10.1
33   54     3     18    12 4473.072  9.1
34   54     6      9    12 5611.097 10.2
35   54     9      6    12 5323.471  9.9
36   72     6     12     9 5153.500  9.8
37   81     9      9     8 5276.787  9.9
38  108     6     18     6 4272.874  8.9
39  108     9     12     6 4847.973  9.5
40  162     9     18     4 4009.765  8.6

agricolae documentation built on Sept. 13, 2017, 1:03 a.m.