A field experiment was carried out in a newly cultivated soil at Falouga, El-Tahrir province, Behira governorate during the summer season (Spring plantation)of 2003 to investigate the effect of different organic manures (i.e. compost, F Y Mor town refuse) each at rate of 20 ton/fed combined with the half recommended doseof mineral fertilizer (NPK) or 2 tons of chicken manure compared with the additionof the recommended dose of N P K at rate of 900, 400 and 200 Kg/fed ammoniumsulphate, calcium superphosphate and potassium sulphate respectively. Applicationof organic manures, i.e. compost, FYM or town refuse each at the rate of 20tons/fed combined with half amount of mineral fertilizer or 2 tons of chickenmanure, increased total microbial count in soil at 60 days after planting compared toboth uncultivated soil and chemical fertilized treatments. In this regard, the highestbacterial count was noticed in case of using FYM + chicken manure, while thehighest count for total fungi and actinomycetes were recorded in the treatment of 20tons compost + half amount of chemical fertilizer (NPK). In addition, using 20 toncompost + 2 tons of chicken manures/fed, reflected the highest dry matter yield,total nitrogen, phosphorus and potassium content in plant foliage as well as totaltuber yield of potatoes compared with other tested treatments.