agridat (version 1.25)

caribbean.maize: Multi-environment trial of maize with fertilization

Description

Maize fertilization trial on Antigua and St. Vincent.

Format

A data frame with 612 observations on the following 7 variables.

isle

island, 2 levels

site

site

block

block

plot

plot, numeric

trt

treatment factor combining N,P,K

ears

number of ears harvested

yield

yield in kilograms

N

nitrogen fertilizer level

P

phosphorous fertilizer level

K

potassium fertilizer level

Details

Antigua is a coral island in the Caribbean with sufficient level land for experiments and a semi-arid climate, while St. Vincent is volcanic and level areas are uncommon, but the rainfall can be seasonally heavy.

There are 8-9 sites on each island.

Plots were 16 feet by 18 feet. A central area 12 feet by 12 feet was harvested and recorded.

The number of ears harvested was only recorded on the isle of Antigua.

The actual amounts of N, P, and K are not given. Only 0, 1, 2, 3.

The digits of the treatment represent the levels of nitrogen, phosphorus, and potassium fertilizer, respectively.

The TEAN site suffered damage from goats on plot 27, 35 and 36.

The LFAN site suffered damage from cattle on one boundary--plots 9, 18, 27, 36.

Electronic version of the data was retrieved from http://lib.stat.cmu.edu/datasets/Andrews/ https://www2.stat.duke.edu/courses/Spring01/sta114/data/andrews.html

References

Also in the DAAG package as data sets antigua and stVincent.

Examples

library(agridat)
data(caribbean.maize)
dat <- caribbean.maize

# Yield and ears are correlated
libs(lattice)
xyplot(yield~ears|site, dat, ylim=c(0,10), subset=isle=="Antigua",
       main="caribbean.maize - Antiqua")

# Some locs show large response to nitrogen (as expected), e.g. UISV, OOSV
dotplot(trt~yield|site, data=dat, main="caribbean.maize treatment response")

# Show the strong N*site interaction with little benefit on Antiqua, but
# a strong response on St.Vincent.
dat <- transform(dat, env=paste(substring(isle,1,1),site,sep="-"))
bwplot(yield~N|env, dat,
       main="caribbean.maize", xlab="nitrogen")