data one;
  input variety fert yield;
  cards;
1 1 37
1 1 40
1 1 45
1 1 46
1 2 47
1 2 45
1 2 42
1 2 40
2 1 40
2 1 43
2 1 47
2 1 42
2 2 37
2 2 47
2 2 41
2 2 47
3 1 41
3 1 46
3 1 52
3 1 45
3 2 51
3 2 55
3 2 52
3 2 57
;

proc glm;
  class variety fert;
  model yield=variety fert variety*fert / clparm;
  lsmeans variety / adjust=tukey pdiff cl;
  estimate 'Fertilizer 1 - Fertilizer 2' fert 1 -1;
run;