wyatt.multi.uniformity {agridat}

Uniformity trial of oats and wheat on the same ground.

Description

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, The average yield was 88 bushels. Wheat was grown in 1926, with an average yield of 32.2 bu/acre. 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

## Not run: 

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")

## End(Not run)