agridat (version 1.12)

williams.barley.uniformity: Yield from a barley uniformity trial

Description

Yield from a barley uniformity trial

Format

A data frame with 720 observations on the following 3 variables.

row

Row position

col

Column position

yield

Yield kg/ha divided by 10

Details

Grown at Roseworthy Agricultural College. Plots were 5 m long (4 m sown, 3.3 m harvested) by 0.75 m wide.

A three-plot seeder was used, planting in a serpentine fashion. Williams noted that it appears that the middle plot of each pass has a lower yield, possibly due to soil compaction from the tractor.

Examples

# NOT RUN {
data(williams.barley.uniformity)
dat <- williams.barley.uniformity

require("lattice")
asp = (15*5)/(48*.75) # true aspect
desplot(yield ~ col*row, dat, aspect=asp,
        main="williams.barley.uniformity")

# Smoothed contour/persp plot like Williams Fig 1b, 2b
dat$fit <- fitted(loess(yield~col*row, dat, span=.1))
contourplot(fit~col*row, data=dat, main="williams.barley.uniformity")
wireframe(fit~col*row, data=dat, zlim=c(100, 350),
          main="williams.barley.uniformity")

# Williams table 1
anova(aov(yield ~ factor(row) + factor(col), dat))

# }