A long term field experiment with corn- clover cropping system was started in 1988 at the Experimental Farm of Assiut University, Assiut, Egypt, to develop an integrated P management model for sustained crop production on the soil type of that experimental farm.  To achieve such goal, the treatments included two rates of crop residues (0 and CR) and six rates of fertilizer P (0, 100, 200, 300, 400, and 500 kg superphosphate fed^-1) which were applied to both corn and Egyptian clover. The crop residues were incorporated into the surface (0.00-0.25 m) soil layer at the end of each growth season (5.45 and 3.71 ton fed^-1 corn stover and Egyptian clover straw, respectively).  The continuous incorporation of corn stover and clover straw each year for 16 years linearly increased soil organic matter (SOM) from 1.23 to 2.39%. However, there was a slight increase in SOM content in the plots received no CR, on average, from 1.00 to 1.23%. The magnitude of changes of Olsen's extractable P forms was associated with the application rates of  superphosphate and the incorporation of crop residues into the soil. As a result of increasing the rate of P fertilization up to 77.5 kg P₂O₅ fed^-1, either with incorporation of crop residues or not, the level of available P reached higher values that could be hazardous for pollution of ground water or surface water.