Two field experiments were carried out in the Agricultural Research and Experimentation center of Fac. of Agric,Moshtohor during 1999 and 2000 seasons to study the effect of organic manures (biogas or refuse compost ) amendment either alone or in combination with Azospirillum inoculation or ammonium sulphate on the growth and yield of maize plants.
Results of this study showed that, highest densities of azotobacters, azospirilra in maize rhizosphere were observed in the treatment of inoculation with A. Iipoferum and supprementation with the half dose of inorganic N- fertilizers
while, the highest densities of phosphate dissolvers was observed in the treatment of inoculation with A. Iipoferum combined with biogas manure( 45 kg N /fed ). The highest records of CO2 evolution were observed in the treatment of biogas amendment with full dose. Maize grains inoculated with A. lioferum and provided with the half dose of inorganic nitrogen fertilizer showed the highest records of N2-ase activity, ammoniacal and nitrate nitrogen as well as available phosphorus. Application of full dose of biogas manure gave higher values of NH4-N and NO3-N than the application of town refuse compost . The highest records of e growth performance, ear characteristics, straw and grain yields of maize were obtained in the treatment of maize grains inoculated with A. Iipoferum and supplemented with half dose of inorganic nitrogen fertilizer. Generally, organic manure application either solely (full dose) or in combination with Azospirillum inoculation or inorganic N-fertilizer gave higher growth performance of maize plants than the (half dose). inoculation with asymptotic N2 -fixing bacteria at sowing and application of half
dose of either inorganic or organic N- fertilizers may be recommended as an alternative for inorganic N- fertilizers application alone to minimize the environmental pollution resulted from the excessive use of chemical fertilizers.
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