{agridat}R Documentation

Uniformity trial of oranges


Uniformity trial of oranges at Riverside, CA, 1921-1927.




A data frame with 1364 observations on the following 4 variables.








yield, pounds/tree for plot


An orchard of naval oranges was planted in 1917 at the University of California Citrus Experiment Station at Riverside. The orchard was maintained under uniform conditions for 10 years.

Eight Washington Navel orange trees in a single row constituted a plot. The planting distance is 20 feet between trees within the row and 24 feet between rows. Every other row was a guard row, so row 2 and row 4 were observational units, while row 3 was a guard row. For example, from row 2 to row 4 is 2*24 = 48 feet. Another way to think of this is that each plot was 48 feet wide, but only the middle 24 feet was harvested. At each end of the plot was one guard tree. Including guard trees at the row ends, each row plot was 10 trees * 20 feet = 200 feet long.

Field width (west-east) 10 plots * 200 feet = 2000 feet.

Field length (north-south) 27 plots * 48 feet = 1296 feet.

An investigation into the variability between plots included systematic soil surveys, soil moisture, soil nitrates, and inspection for differences in infestation of the citrus nematode. None of these factors was considered to be the primary cause of the variations in yield.

After the 7 years of uniformity trials, different treatments were applied to the plots.

Parker et al. state that soil heterogeneity is considerable and first-year yields are not predictive of future yields.

Table 25 has mean top volume per tree for each plot in 1926. Table 26 has mean area of trunk cross section.


E. R. Parker & L. D. Batchelor. (1932). Variation in the Yields of Fruit Trees in Relation to the Planning of Future Experiments. Hilgardia, 7(2), 81-161. Tables 3-9.


Batchelor, L. D. (Leon Dexter), b. 1884; Parker, E. R. (Edwin Robert), 1896-1952; McBride, Robert, d. 1927. (1928) Studies preliminary to the establishment of a series of fertilizer trials in a bearing citrus grove. Vol B451. Berkeley, Cal. : Agricultural Experiment Station


## Not run: 


dat <-

# Parker fig 2, field plan
dat$year <- factor(dat$year)
# 27 rows * 48 ft x 10 cols * 200 feet
desplot(dat, yield ~ col*row|year,
        flip = TRUE, aspect = 27*48/(10*200), # true aspect
        main = "")

# CV across plots in each year. Similar to Parker table 11
cv <- function(x) {
  x <- na.omit(x)
round(100*tapply(dat$yield, dat$year, cv),2)

# Correlation of plot yields across years. Similar to Parker table 15.
# Paker et al may have calculated correlation differently.
dat2 <- acast(dat, row+col ~ year, value.var = 'yield')
round(cor(dat2, use = "pair"),3)
corrgram(dat2, lower = panel.pts, upper = panel.conf,

# Fertility index. Mean across years (ignoring 1921). Parker table 16
dat3 <- aggregate(yield ~ row+col, data = subset(dat, year !=1921 ),
                  FUN = mean, na.rm = TRUE)
round(acast(dat3, row ~ col, value.var = 'yield'),0)

desplot(dat3, yield ~ col*row,
        flip = TRUE, aspect = 27*48/(10*200), # true aspect
        main = " - mean across years")

## End(Not run)

[Package agridat version 1.18 Index]