stephens.sorghum.uniformity {agridat} | R Documentation

## Uniformity trial of sorghum silage

### Description

Uniformity trial of sorghum silage at Chillicothe, Texas, 1915.

### Format

A data frame with 2000 observations on the following 3 variables.

`row`

  row

`col`

  column / rod

`yield`

  yield, ounces

### Details

Grown near Chillicothe, TX in 1915. Rows 40 inches apart. Each row harvested in 1-rod (16.5 ft) lengths. East side higher yielding than west side. Yields are weight (ounces) of green forage each rod-row. Total area harvested: 100*40/12 = 333.33 feet by 20*16.5=330 feet.

Field width: 20 plots * 16.5 ft (1 rod) = 330 feet.

Field length: 100 plots * 40 in = 333 feet

### Source

Stephens, Joseph C. 1928. Experimental methods and the probable error in field experiments with sorghum. Journal of Agricultural Research, 37, 629–646. http://naldc.nal.usda.gov/catalog/IND43967516

### Examples

    ## Not run:

      data(stephens.sorghum.uniformity)
      dat <- stephens.sorghum.uniformity

      dat <- subset(dat, row>2 & row<99) # omit outer two rows
      # mean(dat$yield) # 180.27
      # range(dat$yield) # 75,302 matches Stephens

      # densityplot(~dat$yield) # Stephens figure 3

      # Aggregate 4 side-by-side rows.
      d4 <- dat
      d4$row2 <- ceiling((d4$row-2)/4)
      d4 <- aggregate(yield ~ row2+col, data=d4, FUN=sum)
      d4$row2 <- 25-d4$row2 # flip horizontally

      require(desplot)
      grays <- colorRampPalette(c("#d9d9d9","#252525"))
      desplot(yield ~ row2*col, data=d4,
              aspect=333/330, flip=TRUE, # true aspect
              main="stephens.sorghum.uniformity",
              col.regions=grays(3),
              at=c(500,680,780,1000))
      # Similar to Stephens Figure 7.  North at top.  East at right.

    ## End(Not run)

[Package agridat version 1.16 Index]