williams.barley.uniformity {agridat} | R Documentation

## Uniformity trial of barley

### Description

Uniformity trial of barley at Narrabri, New South Wales, 1984.

### Format

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

`row`

  row

`col`

  column

`yield`

  grain 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.

Field width: 48 plots * .75 m = 36 m

Field length: 15 plots * 5 m = 75 m

### 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. http://doi.org/10.1071/AR9880339

### Examples

    data(williams.barley.uniformity)
    dat <- williams.barley.uniformity

    if(require(desplot)){
      desplot(yield ~ col*row, dat,
              aspect= 75/36, # true aspect
              main="williams.barley.uniformity")
    }

    # Smoothed contour/persp plot like Williams Fig 1b, 2b
    require("lattice")
    dat$fit <- fitted(loess(yield~col*row, dat, span=.1))
    contourplot(fit~col*row, data=dat,
                aspect=75/36, region=TRUE, col.regions=RedGrayBlue,
                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))

[Package agridat version 1.16 Index]