hunter.corn.Rd
Corn yield response to nitrogen
A data frame with 54 observations on the following 4 variables.
nitro
nitrogen fertilizer, pound/acre
year
year
loc
location
yield
yield, bu/ac
Experiments were conducted in eastern Oregon during the years 1950-1952.
Planting rates varied from 15,000 to 21,000 planter per acre.
Albert S. Hunter, John A. Yungen (1955). The Influence of Variations in Fertility Levels Upon the Yield and Protein Content of Field Corn in Eastern Oregon. Soil Science Society of America Journal, 19, 214-218. https://doi.org/10.2136/sssaj1955.03615995001900020027x
James Leo Paschal, Burton Leroy French (1956). A method of economic analysis applied to nitrogen fertilizer rate experiments on irrigated corn. Tech Bull 1141. United States Dept of Agriculture. books.google.com/books?id=gAdZtsEziCcC&pg=PP1
library(agridat) data(hunter.corn) dat <- hunter.corn dat <- transform(dat, env=factor(paste(loc,year))) libs(lattice) xyplot(yield~nitro|env, dat, type='b', main="hunter.corn - nitrogen response curves")