agridat (version 1.23)

nass.corn: U.S. historical crop yields by state

Description

Yields and acres harvested in each state for the major agricultural crops in the United States, from approximately 1900 to 2011. Crops include: barley, corn, cotton, hay, rice, sorghum, soybeans, wheat.

Usage

nass.barley
  nass.corn
  nass.cotton
  nass.hay
  nass.sorghum
  nass.wheat
  nass.rice
  nass.soybean

Format

year

year

state

state factor

acres

acres harvested

yield

average yield

Details

Be cautious with yield values for states with small acres harvested.

Yields are in bushels/acre, except: cotton pounds/acre, hay tons/acre, rice pounds/acre.

Each crop is in a separate dataset: nass.barley, nass.corn, nass.cotton, nass.hay, nass.sorghum, nass.wheat, nass.rice, nass.soybean.

Examples

if (FALSE) {

library(agridat)
data(nass.corn)
dat <- nass.corn

# Use only states that grew at least 100K acres of corn in 2011
keep <- droplevels(subset(dat, year == 2011 & acres > 100000))$state
dat <- droplevels(subset(dat, is.element(state, keep)))

# Acres of corn grown each year
libs(lattice)
xyplot(acres ~ year|state, dat, type='l', as.table=TRUE,
       main="nass.corn: state trends in corn acreage")

## Plain levelplot, using only states
## libs(reshape2)
## datm <- acast(dat, year~state, value.var='yield')
## redblue <- colorRampPalette(c("firebrick", "lightgray", "#375997"))
## levelplot(datm, aspect=.7, col.regions=redblue,
##           main="nass.corn",
##           scales=list(x=list(rot=90, cex=.7)))

# Model the rate of genetic gain in Illinois as a piecewise regression
# Breakpoints define periods of open-pollinated varieties, double-cross,
# single-cross, and transgenic hybrids.

dil <- subset(nass.corn, state=="Illinois" & year >= 1900)
m1 <- lm(yield ~ pmin(year,1932) + pmax(1932, pmin(year, 1959)) +
         pmax(1959, pmin(year, 1995)) + pmax(1995, year), dil)
signif(coef(m1)[-1],3) # Rate of gain for each segment
plot(yield ~ year, dil, main="nass.corn: piecewise linear model of Illinois corn yields")
lines(dil$year, fitted(m1))
abline(v=c(1932,1959,1995), col="wheat")

}