alfalfa.split.plot {asbio}

An agricultural split plot design

Description

An experiment was conducted in Iowa in 1944 to see how different varieties of alfalfa responded to the last cutting day of the previous year (Snedecor and Cochran 1967). We know that in the fall alfalfa can either continue to grow, or stop growing and store resources belowground in roots for growth during the following year. Thus, we might expect that later cutting dates inhibits growth for the following year. On the other hand, if plants are cut after they have gone into senescence, there should be little effect on productivity during the following year. There are two factors: 1) variety of alfalfa (three varieties were planted in each of three randomly chosen whole plots), and 2) the date of last cutting (Sept 1, Sept. 20, or Oct. 7). The dates were randomly chosen split plots within the whole plots. Replication was accomplished using six blocks of fields.

Usage

data(alfalfa.split.plot)

Format

The dataframe contains four variables:

yield

Alfalfa yield (tons per acre).

variety

Alfalfa variety. A factor with three levels "L"= Ladak, "C" = Cosack, and "R" = Ranger describing the variety of alfalfa seed used.

cut.time

Time of last cutting. A factor with three levels: "None" = field not cut, "S1" = Sept 1, "S20" = Sept. 20, or "O7" = Oct. 7.

block

The block (whole plot replicate). A factor with six levels: "1", "2", "3", "4", "5", and "6".

Source

Snedecor, G. W. and Cochran, G. C. (1967) Statistical Methods, 6th edition. Iowa State University Press.