Fig. 2. Treatment means for DM yield, Year 2. Model equation: t ha1 = 1.071 + (NA x 1.959 x 102) + (PA x.129) + (NA x PA x 1.746 x 104) (NA x NA x 3.079 x 105) (PA x PA x 1.690 x 103), (n = 83, R2 = 0.93, s = 0.764).