agridat (version 1.5)

caribbean.maize: Maize fertilization trial on Antigua and St. Vincent

Description

Maize fertilization trial on Antigua and St. Vincent.

Usage

data(caribbean.maize)

source

D.F. Andrews and A.M. Herzberg. 1985. Data: A Collection of Problems from Many Fields for the Student and Research Worker. Springer. Retrieved from http://lib.stat.cmu.edu/datasets/Andrews/.

Details

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

References

Also in the DAAG package as antigua, stVincent.

Examples

dat <- caribbean.maize

# Yield and ears are highly correlated
xyplot(yield~ears|site, dat, ylim=c(0,10), subset=isle=="Antigua")

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