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Effect of biochar produced from sewage sludge on tomato (Solanum lycopersicum L.)

Velli Paraskevi

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Year 2019
Type of Item Diploma Work
Bibliographic Citation Paraskevi Velli, "Effect of biochar produced from sewage sludge on tomato (Solanum lycopersicum L.)", Diploma Work, School of Environmental Engineering, Technical University of Crete, Chania, Greece, 2019
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Ιn the context of this undergraduate thesis the production of biochar was studied so as to apply it to soil and study its effect on the cultivation of tomatoes (Solanum Lycopersicum L.). The biomass used in the production of biochar was anaerobically digested and thermo-dehydrated sludge from urban sewage - a mixture of primary and secondary sludge- from the Psyttaleia Wastewater Treatment Plant, while the soil was taken from a cultivated area of Chania and it was sandy loam. Following its production at 300oC and its characterization, the biochar was applied to the soil for the cultivation of Solanum Lycopersicum L. The cultivation period lasted for three months. There were four treatments, with three repetitions each. A total of twelve perforated plastic pots with a 10 kg capacity were installed. Specifically, the treatments were the Control (untreated soil), soil with 2% biochar (BC-SS), soil with 2% compost (Compost) and a mixture of biochar and compost at a 2% level (BC—SS+Compost). The aim of the study was to examine whether sludge biochar in combination with or without compost effects: A. The dry weight and morphological characteristics of the plant. B. The concentrations of macronutrients, micronutrients and heavy metals in aboveground and belowground plant tissues. C. The soil properties, including the nutrients and heavy metals.With the application of biochar a number of soil properties exhibited substantial improvement. The TOC increased as did the NO3–N and NH4–N. Additionally, an increase in the micronutrients and macronutrients in the soil was also observed. According to the results the application of biochar in combination with or without compost improved substantially plant growth. Forty days after the application of biochar, the plants treated with BC—SS showed a 34.1% increase in height compared to the Control. The dry mass of the aboveground and belowground plant tissue equally increased. Plants treated with BS—SS+Compost had the largest increase in the fruit and roots, those treated with BC—SS in the stems. The addition of BC—SS+Compost decreased the amount of N in the stems of the tomatoes. The addition of Compost substantially increased the concentration of P in the stems and leaves as well as the concentration of K in the roots. The addition of biochar, compost as well as their combination increased the amount of K in the leaves of the plant. The addition of BC—SS+Compost decreased the concentration of Ca in the tomato fruit, whereas the application of Compost increased the Ca in the fruit. The concentration of Na was substantially increased with the addition of compost in all plant tissues. The concentration of Mg in the plant tissue was minimally affected in all treatments. The application of BC—SS, Compost and BC—SS+Compost decreased Fe concentration in the tomato fruit, whereas the Compost substantially increased Mn content in the stems and fruit. The concentration of heavy metals was quite low. Specifically, traces of Cr, Ni and Co were found only in roots of those treated, while Si was present in the roots and stems. As, Mo and Pb were present in all plant tissue without them surpassing the permissible levels established for vegetables. Finally, no traces of Hg, Se and CD were found in any of the tissues.The addition of biochar improves the soil characteristics and increases the plant yield. However, before its use all the different parameters such as the type of biomass, soil, application dose, cultivation, etc. must be taken into account so as to have the desired results.

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