youssef zeroual

The deterioration of agricultural soil can be alleviated by maintaining an appropriate level of soil organic matter by using organic amendments such as compost and biochar. The aim of this study was to investigate the effects of olive waste-based compost, wood-based biochar and their combination on the chemical and microbial properties of loamy clay soil and the agrophysiological traits of maize.

 Zea mays was grown under greenhouse conditions for 3 months in pots filled with alkaline soil collected from 0-30 cm depth. The experiment was arranged in a completely randomized design with 5 replicates and 3 treatments: compost-soil [1:10 (v/v)], biochar-soil [1:20 (v/v)] and (1:2)-ratio biochar-compost combination (BCC).

Biochar addition singly or in BCC increased soil TOC, EC, and pH. Furthermore, adding biochar to compost increased the levels of macro- and micronutrients compared to those under single application of biochar. The soil fertility improved significantly with regard to available phosphorus and potassium, nitrogen, and micronutrients. Single application of biochar had a negative impact on mycorrhizal symbiosis and was statistically insignificant for soil viable cultivable microorganisms.

Overall, single application of compost gave the best results in terms of plant growth and soil fertility improvement; thus, a synergistic effect of both amendments was not observed, which could be due to the quantity of the applied biochar and the duration of the experiment.

In recent years, biodiesel from microalgae has received large interest around the world, as sustainable energy for biofuel production. Mineral fertilizers can be a promising source for the development of low cost culture media. We investigate the influence of fertilizer-based media: MAP, TSP, Phosphoric acid and Ammonitrate on cell viability, nutrients uptake, biomass, lipids production and lipids profile of 3 microalgae strains. The best biomass production was 2.105 g L-1, 1.95g.L-1 and 1.75g.L-1 for D. tertiolecta, Isochrysis sp.and Tetraselmis sp cultured in TSP, MAP and H3PO4(54%)based-media respectively, compared to control medium (1.85, 1.76 and 1.71 g L-1 respectively). Lipid content of all strains in fertilizer-based media was similar to control. The lipid profile showed that FAMEs of all microalgae underwent a significant reduction in PUFAs for fertilizers based-media, which improves the quality of biodiesel. Mineral fertilizers are a promising source that can be a low-cost microalgae production base at the industrial level.