PLANT RESPONSE TO BIOFERTILIZATION IN SOIL AMENDED WITH IRRADIATED SEWAGE SLUDGE

Abstract

The present work is a trial to cultivate desert sandy areas with crop plants through reclamation using natural additives for the biosafety of the ecosystem. For this target, natural sandy soil was amended with sewage sludge and different biofertilizers, either alone or in combination prior to cultivation. Sewage sludge (dried) was added at a relatively low amount in order to improve the soil properties and enrich its N - P - K and other nutrient elements, to the extent avoiding the risk that may be posed by accumulation of heavy metals. Irradiation of sewage sludge was also carried out in order to minimize or completely prevent the occurrence of pathogenic microorganisms. The inoculants used as biofertilizers were the N2 - fixers Rhizobium (Rh) and Azospirillum (Sp), and Arbuscular Mycorrhizae (AM). These inoculants were added either solely or as dual or triple inoculants in sandy soil amended or unamended with sewage sludge. The effect of the above mentioned soil treatments was investigated on the growth and productivity of two main crops, one as a legume (clover) and the other as a cereal (wheat). In these plants, the concomitant uptake ofN,P,K and certain microelements (Fe, Mn, Zn and Pb) were also recorded. The most interesting results are summarized in the following: