nass.corn {agridat} | R Documentation

## 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.

### Source

United States Department of Agriculture, National Agricultural Statistics Service. http://quickstats.nass.usda.gov/

### Examples

    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
    require(lattice)
    xyplot(acres ~ year|state, dat, type='l', as.table=TRUE,
           main="nass.corn: state trends in corn acreage")

    ## Plain levelplot, using only states
    ## require(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")

[Package agridat version 1.16 Index]