A two year (2013 and 2014) field trial was conducted to study the residual effect of different fertility levels of rice mill ash (RMA) on maize-soybean intercrop. The experiment was arranged in a randomized complete block design (RCBD) comprising of nine (9) treatments and three (3) replications. The treatments where sole maize (SMO), sole soybean (SBO), maize/soybean intercrop without application of rice mill ash (IMBO), soybean + 10 t/ha rice mill ash (SB10), sole maize + 10 t/ha rice mill ash (SM10), maize - soybean intercrop + 10 t/ha rice mill ash (IMB10), sole maize + 20 t/ha rice mill ash (SM20); sole soybean + 20 t/ha rice mill ash (SB20) and maize/soybean intercrop + 20 t/ha rice mill ash (IMB20). Data generated was subjected to analysis of variance of which the result of the study showed that for 2 years under study, incorporated rice mill ash (RMA) and intercropping system significantly increased the soil productivity, yield and yield components of maize and soybean studied. The RMA at the rate of 20t/ha performed competitively better than the other treatments with strong residual impact on the parameters assessed. Findings from the study equally showed an intercrop advantage.