الفهرس 
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Abstract
The present study was carried out to investigate the role of rice straw-derived biochar (Black Carbon; B.C.) as a soil amendment comparing with algal biofertilizer (A.Bio.) and mineral fertilizer (NPK) for alleviation the toxic effect of soil salinity stress during the germination, growth and yield stages of cowpea plant (Vigna unguiculata L. Walp.). Firstly, the biomass of rice straw was collected and pyrolyzed at 450ºC for 2h for biochar (B.C.) processing then was analyzed. Preliminary experiments were conducted to study the differential responses of cowpea at different concentrations of salt stress (0, 50, 100, 150, 200, 250 and 300 mM NaCl) and determination the effective dose of applied mineral fertilizer (NPK) mixed with B.C. and A.Bio. Depending on the results of these preliminary experiments, the sub lethal concentration of NaCl was 200mM NaCl and the most pronounced results achieved by reducing the rate of utilized mineral fertilizers (NPK) used in agriculture nowadays by 25%.The main experiment was achieved during the growing season of Vigna unguiculata (L.) Walp. in April. B.C. (2g/Kg) mixed with the soil before sowing. Mineral fertilizer (NPK) was applied at the rate of 50, 75 and 100%. A.Bio. was applied to soil (3g/Kg). Seeds with uniform size and shape were selected and divided into two main groups; the first group without NPK and the second one with 75%NPK. The first main group is divided into eight subgroups; The 1st one contained soil only (control). The 2nd contained soil mixed with B.C. The 3rd contained soil mixed with A.Bio. The 4th contained soil mixed with B.C. and A.Bio. The 5th contained salinity treatment (200 mM NaCl). The 6th contained soil mixed with B.C. and treated with salinity. The 7th contained soil mixed with A.Bio. and treated with salinity. The 8th contained soil mixed with B.C. with A.Bio. and treated with salinity. The second main group contained soil mixed with 75%NPK and divided into eight subgroups with the same classification as the first main group but with the addition of NPK. The harvesting was carried out at 3 growth stages; seedling (21-day old), vegetative (45-day old) and yield (90-day old) stages.