El-Tapey, H.M.A., Mona, M. Aly, Doaa, M., Khalifa, *Ibrahim, M. Elareny and Heba, SH. Shehata( 2019). Role of microbiota and mineral nitrogen fertilizers for improving sandy soil properties and canola (brassica napus l.) Yield productivityN. Egypt. J. Microbiol. Vol. 54, Septamper, 2019. 31
Abstract: The study was conducted in sandy textured soil under sprinkler irrigation of Ismailia Agricultural Research Station, Ismailia Governorate, Egypt. Two successive seasons through 2015/2016 and 2016/2017 were occurred to evaluate some biological effective treatments by different levels of mineral recommended nitrogen fertilizer (60 kg N as ammonium sulfate) i.e., 50, 75 and 100% on physiochemical properties of soil and quantity and quality of canola yield (Brassica napus L.). The biological treatments were either combination between some genera of bacteria
(Azotobacter chroococcum and Peanebacillus polymyxa), some genera of
cyanobacteria (Nostoc muscorum and Anabaena oryzae) or the mixture among all tested microbes. Generally, root length,shoot height, number of branches, and root colonization percentage, dehydrogenase and nitrogenase activities significantly increased under the mixture of bacteria and cyanobacteria in the presence of 75 % of mineral nitrogen fertilizer during the two successive seasons as compared with solo
doses of nitrogen fertilizers. The highest values of chlorophyll (a), (b) and carotenoids were, 2.56, 0.84, 0.99 and 2.6, 0.83, 0.98 mg g-1 fresh weight in the first and second seasons, respectively. The same trend was noticed for NPK contents, yield of seeds
(kg fed-1), weight of 1000 seed, pod numbers and oil percentage. However, no
significant differences between 50 % and 75 % of mineral nitrogen fertilizers with the mixture of bacteria and cyanobacteria were occurred for the majority of growth and yield parameters. The investigation also pointed out to significant differences between
bacterial and cyanobacterial treatments. The data exerted that bacterial treatments were more preferable than cyanobacterial treatments through the two successive seasons. Fertility status as NPK availability significantly increased by using the mixture of bacteria and cyanobacteria together in the presence of 50 or 75 % N rates
than using recommended dose and other individual mixtures of bacteria or
cyanobacteria with the same rates of mineral nitrogen application. Soil aggregation significantly increased under the mixture of cyanobacteria combined with 75 % N than the mixture of bacteria, and the chemical nitrogen treatments were recorded the least values. Soil physical properties, i. e., total soil porosity, micro-pores (<28.8 μ) and soil moisture constant values significantly increased by the combination between biofertilizer and mineral nitrogen implementation and the superiority treatment was for the mixture of bacteria and cyanobacteria under 75 or 50 % N, the opposite trend
was observed for soil bulk density and macro-pores (>28.8 μ) which decreased
under all the microorganisms inoculation and / or chemical nitrogen fertilizers
treatments.
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