OBS    BLOCK    FERT    VAR    YIELD
  1      1        1      1      35.4
  2      1        1      2      37.9
  3      2        1      1      41.6
  4      2        1      2      40.3
  5      1        2      1      36.7
  6      1        2      2      38.2
  7      2        2      1      42.7
  8      2        2      2      41.6
  9      1        3      1      34.8
 10      1        3      2      36.4
 11      2        3      1      43.6
 12      2        3      2      42.8
 13      1        4      1      39.5
 14      1        4      2      40.0
 15      2        4      1      44.5
 16      2        4      2      47.6