kalamkar.wheat.uniformity {agridat} | R Documentation

## Uniformity trial of wheat

### Description

Uniformity trial of wheat at Rothamsted, UK in 1931.

### Usage

    data("kalamkar.wheat.uniformity")

### Format

A data frame with 1280 observations on the following 4 variables.

`row`

  row

`col`

  column

`yield`

  yield, grams/half-meter

`ears`

  ears per half-meter

### Details

Kalamkar's paper published in 1932. Estimated crop year 1931.

Plot 18 of the Four Course Rotation Experiment, Great Hoos, at Rothamsted, UK was used. Sown with Yeoman II wheat.

Field width = 16 segments * 0.5 meters = 8 meters.

Field length: 80 rows * 6 inches apart = 40 feet.

The grain yield and number of ears for each half-meter length were recorded. This is quite a small field, only 1/40 acre in size.

Edge rows have higher yields. Row-end units have higher yields than interior units. These border effects are significant. Variation between rows is greater than variation within rows. Negative correlation between rows may indicate competition effects.

For ears, Kalamkar discarded 4 rows from each side and 3 half-meter lengths at each end.

Kalamkar suggested using four parallel half-meter rows as a sampling unit.

Note, the Rothamsted report for 1931, page 57, says: During the year three workers (F. R. Immer, S. H. Justensen and R. J. Kalamkar) have taken up the question of the most efficient use of land in experiments in which an edge row must be discarded...

### Source

Kalamkar, R. J (1932). A Study in Sampling Technique with Wheat. The Journal of Agricultural Science, Vol.22(4), pp.783-796. https://doi.org/10.1017/S0021859600054599

### References

None.

### Examples

    ## Not run:

      data(kalamkar.wheat.uniformity)
      dat <- kalamkar.wheat.uniformity
      plot(yield ~ ears, dat, main="kalamkar.wheat.uniformity")

      # totals match Kalamkar
      sum(dat$yield)
      sum(dat$ears)

      require(desplot)
      desplot(ears ~ col*row, dat,
              flip=TRUE, aspect=(80*0.5)/(16*1.64042), # true aspect
              main="kalamkar.wheat.uniformity - ears")
      desplot(yield ~ col*row, dat,
              flip=TRUE, aspect=(80*0.5)/(16*1.64042), # true aspect
              main="kalamkar.wheat.uniformity - yield")

      # Show the negative correlation between rows
      ## require(asreml)
      ## require(lucid)
      ## dat <- dat
      ##   arrange(rowf,colf)
      ## m1=asreml(yield ~ 1, data=dat, rcov= ~ ar1(rowf):ar1(colf))
      ## vc(m1)
      ##  ##     effect component std.error z.ratio constr
      ##  ## R!variance  81.54      3.527      23        P
      ##  ## R!rowf.cor  -0.09465   0.0277     -3.4      U
      ##  ## R!colf.cor   0.2977    0.02628    11        U

    ## End(Not run)

[Package agridat version 1.16 Index]