COMBINED APPLICATION OF VARIOUS SOURCES OF ORGANIC FERTILIZERS WITH BIOFERTILIZERS FOR IMPROVEMENT POTATO PRODUCTIVITY AND SOIL FERTILITY STATUS

A field experiments were carried out during two successive seasons 2019 and 2020 in a private farm at Belqas district, Al-Daqahlia Governorate, Egypt to assay the effect of various sources of organic fertilizers (farmyard manure, compost, chicken manure and spent coffee ground) added either solely or combination with biofertilizers (N-fixers and PK-dissolving bacteria) on the growth performance and productivity of potato plants. Results showed that the soil amended with chicken manure (24.7m3/ha.) and inoculated by dual biofertilizers i.e. Paenibacillus polymyxa as nitrogen fixing bacteria and Enterobacter cloacae as phosphate and potassium solubilizing bacteria that introduced as talc-based formulation containing mixed strains, significantly enhanced remaining nutrients in the soil post-harvest; Moreover, densities of bacterial population at 90 days’- time interval significantly increased. Also, the highest vegetative growth, yield attributes and tuber quality were recorded for the same treatment. On other hand, this treatment recorded the lowest nitrate content for both seasons. It is worth mentioning that soil amended with spent coffee grounds (27.17m3ha.-1) with bacterial inoculation has a positive effect on improving soil fertility and potato productivity.