Bray has modified the mitscherlich equation to

The equation introduced by Mitscherlich has been generally used to express nutrient-yield relationships as follows: $${\bf{y = A}}\left( {{\bf{1 - }}{{\bf{e}}^{{\bf{ - eb - ex}}}}} \right)$$
Bray has modified the mitscherlich equation to $${\bf{log}}\left( {{\bf{A - y}}} \right){\bf{ = logA - }}{{\bf{C}}_{\bf{1}}}{\bf{b - cx}}$$
Where A = % theoretical maximum yield, y = actual yield obtained in q ha^-1, b = native soil test value in kg ha^-1, x = fertilizer nutrient applied in kg ha^-1, c₁ and c = constants i.e., the efficiency of soil and fertilizer nutrients respectively.