Uniformity trial of sorghum silage

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. https://naldc.nal.usda.gov/catalog/IND43967516

Examples

# \dontrun{

library(agridat)
  
  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
  
  libs(desplot)
  grays <- colorRampPalette(c("#d9d9d9","#252525"))
  desplot(d4, yield ~ row2*col,
          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.
  
# }