Search

The compost tested in this study resulted from the anaerobic fermentation process of sewage sludge with cereal straw. Processing and post-treatment were made by Biotechnological Research Centre within INCD ECOIND from Bucharest. Experimental program included testing the effect of fertilizer in quantities of 25 t, 50 t and 100 t compost / ha on the production of soya beans. It was also investigated the influence of the combination of fertilization with compost and inorganic fertilization with levels of 200 kg, respectively, 400 kg NPK / ha. Was analyzed the following productivity indicators: plant density, number of floors of pods, number and weight of pods and total beans production, in full ripening stage. In the case of fertilization only with composted sludge, production of peas and beans was higher in variants with 50 t / ha and 100 t / ha (2095 kg and 1990 kg grain / ha). Therefore, doubling the amount of compost does not provide corresponding increase yields of soybeans. Combining organic and inorganic fertilization determine a proportional production increase only for the total biomass production. The tested compost is a good organic fertilizer and the amount that provides the greatest soybeans production is 50 t / ha. [ABSTRACT FROM AUTHOR]

In sewage sludge from urban wastewater treatment stations can often be find high levels of Ni, Pb, Cu, Zn, Mn and Cd. Aerobic or anaerobic composting of this sewage sludge does not eliminate the possibility of bioaccumulation of these metals in plants through metabolic processes of phytoextraction type. Researches regarding the accumulation degree of heavy metals through phytoextraction processes were performed on soybean plants (Glycine max), Condor variety. Plants were fertilized with anaerobic composted sludge in amounts of 25 t of / ha, 50 t / ha and 100 t / ha. The chemical analysis was done on an average sample of three repetitions. Metal concentration in soybeans was analyzed by reporting to the maximum allowance level for sheep, considered one of the most sensitive farm species to heavy metal toxicity. Our results showed a higher level than normal with 5.8 mg / kg only in the case of copper ions. Zn, Pb, Mn and Cd concentration in soybeans was below the maximum allowance limits set by the rules of feeding farm animals. Also, heavy metal content of soybeans was not affected by the amount of composted sludge used as fertilizer. [ABSTRACT FROM AUTHOR]