agridat (version 1.8.1)

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

Description

Yield from a barley uniformity trial

source

Williams, ER and Luckett, DJ. 1988. The use of uniformity data in the design and analysis of cotton and barley variety trials. Australian Journal of Agricultural Research, 39, 339-350.

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

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)
wireframe(fit~col*row, data=dat, zlim=c(100, 350))

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