Biochar derived from agricultural residue can be used for soil improvement to enhance soil fertility and soil chemical, physical and biological properties. The objective of this research was to study the effects of biochar on soil fertility of sandy loam soil and clay soil in greenhouse condition. Treatments were laid out in 2x5 Factorial in RCB with four replicates. The first factor was two soil types: 1) Clay soil (Cl) and 2) Sandy loam soil (SL). The second factor was five biochar (BC) rates: 0 16 32 48 and 64 g/10 kg soil (equaling to 0.5, 1.0, 1.5 and 2.0 ton/rai). In each treatment; nitrogen, phosphate and potash fertilizers were applied (based on soil analysis). The results showed that the addition of biochar to clay soil increased available soil nutrient and total nutrient uptake in plant higher than (p<0.01) sandy loam soil. Biochar application to clay soil significantly increased growth and dry matter of maize (p<0.01). The addition of biochar also showed a tendency to increase soil organic matter and exchangeable potassium in clay soil higher than in sandy loam soil (p<0.01). However, available phosphorus in clay soil was lower than sandy loam soil. Moreover, it was found that the soil-biochar application in both soils types increased nitrate retention greater than the soil without biochar. The results of this study indicated that biochar can be used to increase the fertility of the clay soil at the rate of 1.5 tons/rai.