Two field experiments were conducted during the fall (Nili) season of
1998/1999 and 1999/2000 at Abou Awad Village, Aga, Dakahlia Governorate, on
potato cv. Oiamont to investigate the effect of compost Le. compost 1 (Rice straw and
Wheat straw), compost 2 (City garbage manure) and some biofertilizers (Biogein,
Phosphorein, phosphate dissolving bacteria (POB) and silicate decomposing bacteria
(SOB) as a substitute for chemical fertilizers on potato plants. The obtained data show that the plants stand percentage at 45 days after
planting was the highest with treatment 8 (compost 2 (City garbage manure) + Yz
treatment 2 (Rock phosphate + Feldspar + Biogein + Phosphorein + Bacil/us circulans).
Vegetative growth, in terms of plant height, number of main stems/plant, foliage fresh
weight/plant (g) and foliage dry weight (%) at 75 (OAP) were increased by using the
mineral fertilizer (control). NPK (%) in leaves at 75 (OAP) and tubers at harvesting were
also increased by treatment of compost 2 (City garbage manure) + Y, treatment 3 (Rock
jj~csphate + Feldspar+ Biogein + Bacillus megatrium + Bacillus circulans) during the
both seasons.' C;: the other hand, to~1 tubers yield (tonlfed.), number of tubers/plant,
average weight of tuberSi.,ioc:' (;1 '1nd dry weight of tubers (%) were significantly
increased with this treatment in both seascns. Whi!" t:"!?'1tment of compost 1 increased
starch ('Yo) in tubers, also the highest reduction in nitrate concentrauon (plJlllj'iii tubers - ,.
was recorded for treatment 3 (Rock phosphate + Feldspar+ Biogein + Bacillus
megatrium + BacillUS circulans) in the both seasons. Generally, the results indicate that using treatment of compost 2 (City
garbage manure) + Y, treatment 3 (Rock phosphate + Feldspar+ Biogein + Bacil/us
megatrium + Bacillus circulans) as a substitute of chemical fertilizers of potato plants
improved tuber yield, quality and saved considerable amount of mineral fertilizers of
NPK requirements. Likewise, inoculation by mixture of biofertilizers may be helpful in
reducing the pollution of environment and may be recommended in potato bio-
production.