Uniformity trial of timothy — holtsmark.timothy.uniformity • agridat

Uniformity trial of timothy hay circa 1905

data("holtsmark.timothy.uniformity")

Format

A data frame with 240 observations on the following 3 variables.

row: row
col: column
yield: yield per plot, kg

Details

Field width: 40 plots * 5 m = 200 m.

Field length: 6 plots * 5 m = 30 m

Holtsmark & Larsen used this trial to compare standard deviations of different sized plots (combined from smaller plots).

Source

Holtsmark, G and Larsen, BR (1905). Om Muligheder for at indskraenke de Fejl, som ved Markforsog betinges af Jordens Uensartethed. Tidsskrift for Landbrugets Planteavl. 12, 330-351. (In Danish) https://books.google.com/books?id=MdM0AQAAMAAJ&pg=PA330 https://dca.au.dk/publikationer/historiske/planteavl/

Uber die Fehler, welche bei Feldversuchen, durch die Ungleichartigkeit des Bodens bedingt werden. Die Landwirtschaftlichen Versuchs-Stationen, 65, 1--22. (In German) https://books.google.com/books?id=eXA2AQAAMAAJ&pg=PA1

References

Theodor Roemer (1920). Der Feldversuch.

Examples

# \dontrun{

library(agridat)
data(holtsmark.timothy.uniformity)
dat <- holtsmark.timothy.uniformity

# Define diagonal 'check' plots like Holtsmark does
dat <- transform(dat,
                 check = ifelse(floor((row+col)/3)==(row+col)/3, "C", ""))
                 
libs(desplot)
desplot(dat, yield ~ col*row,
        flip=TRUE, text=check, show.key=FALSE,
        aspect=30/200, # true aspect
        main="holtsmark.timothy.uniformity")

# sd(dat$yield) # 2.92 matches Holtsmark p. 348

# }