Uniformity trial of oats and wheat on the same ground.

Usage

data("wyatt.multi.uniformity")

Format

A data frame with 258 observations on the following 5 variables.

col: column
row: row
yield: yield, bu/ac
year: year
crop: crop

Details

Experiments conducted at the Soils Experimental field at the University of Alberta, Canada.

Oats were grown in 1925, with average yield 88 bu/ac.

Wheat was grown in 1926, with average yield 32.2 bu/ac.

The data reported are relative yields within each year.

The plot size in rows 1 and 2 (Series A and B in the original paper) is 1/10th acre. The plot size in row 3 is 1/11 acre.

Field length: 3 plots (140 ft, 140 ft, 128 ft) + 2 roads * 16 feet = 440 feet.

Field width: 43 plots * 37 ft = 1591 feet.

Source

F. A. Wyatt (1927). Variation in plot yields due to soil heterogeneity. Scientific Agriculture, 7, 248-256. Table 1. https://doi.org/10.4141/sa-1927-0020

References

None

Examples

if (FALSE) { # \dontrun{

library(agridat)
data(wyatt.multi.uniformity)
dat <- wyatt.multi.uniformity

# range of yields. Wyatt has 48.6 bu/ac for oats, 10.4 for wheat
# diff(range(na.omit(subset(dat, crop=="oats")$yield)/100*88)) # 48.4
# diff(range(na.omit(subset(dat, crop=="wheat")$yield)/100*32.8)) # 10.5 

# std dev. Wyatt has 9.18 bu/ac for oats, 2.06 for wheat, 2.06 for wheat
# sd(na.omit(subset(dat, crop=="oats")$yield)/100*88) # 9.11
# sd(na.omit(subset(dat, crop=="wheat")$yield)/100*32.8) # 2.14

# correlation across years. Wyatt has .08
# cor(reshape2::acast(dat, row+col ~ crop, value.var="yield"), use="pair")

# Fig 3
libs(lattice)
xyplot(yield ~ col|factor(row), dat, group=crop,
       main="wyatt.multi.uniformity",
       type='l', layout=c(1,3), auto.key=TRUE )                

libs(desplot)
desplot(dat, yield ~ col*row, subset=crop=="oats",
        tick=TRUE,
        aspect=(440)/(1591), # true aspect
        main="wyatt.multi.uniformity - 1925 oats")
desplot(dat, yield ~ col*row, subset=crop=="wheat",
        aspect=(440)/(1591), # true aspect
        main="wyatt.multi.uniformity - 1926 wheat")
} # }