agridat (version 1.25)

holtsmark.timothy.uniformity: Uniformity trial of timothy grass in Norway

Description

Uniformity trial of timothy grass in Norway

Usage

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

The experiment was probably conducted shortly before 1898. Ehrenberg says the data come from Norway.

The test plot was a 3-year old Timothy grass meadow, uniform to the eye. The individual plots were square 1/16 are in size. An are is 10m x 10m, so 1/16 are is 2.5m x 2.5m

Bastien Larsen sent the data to Ehrenberg, who published the plot yields.

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).

Note: The two datasets in agridat, holtsmark.timothy.uniformity and larsen.timothy.uniformity refer to the same trial. Heatmaps show the same trends for the two datasets. The 'larsen' data has been aggregated 2x2 to create the 'holtsmark' data. Both versions appear in published papers and are included here.

References

Theodor Roemer (1920). Der Feldversuch. Page 67, table 11. https://www.google.com/books/edition/Arbeiten_der_Deutschen_Landwirtschafts_G/7zBSAQAAMAAJ

Larsen, B. R. (1898). Om metoder för fältförsök. Ber. Andra nordiska Landsbrukskongressen in Stockholm 1897. P. 72-84. Discussion 85-94. (document not found)

Examples

if (FALSE) {

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

}