Date of Award
Master of Science (MS)
Dr. Elke Neumann
Hydroponic plant production involves the cultivation of plants in absence of soil. In this system, the supply of the plant root with water and nutritional elements occurs via a nutrient solution made of inorganic salts. Hydroponic plant cultivation often achieves higher yields, water use efficiencies and quality of crops compared with soil production. In addition, it renders the farming system independent from soil properties. However, the currently available systems rely on the steady input of non-renewable inorganic salts. Unlike soil-based systems, hydroponics, so far, do not offer feasible opportunities for recycling nutritional elements from within crop residues or organic waste materials. The main aim of this thesis was thus to elucidate the potential of producing nutrient solutions suitable for hydroponic plant cultivation from locally produced vegetable crop residues, commercial compost, and biosolids. In a first experiment, the release of soluble nutritional elements from the organic test materials was investigated over time and for different substrate/water ratios. Dried and ground organic substrate samples were placed into nylon mesh bags and allowed to extract and mineralize in aerated water for up to 23 days. The release of nutritional elements was monitored at intervals of three days and revealed that the highest amounts of soluble nutrients were present in the extraction solution between 3 and 6 days after the set-up of the trial. The use of one L of water for the extraction of six g of dry organic substrate resulted in the highest nutrient release. In a second experiment, the ability of two different nutrient solutions produced from organic waste materials to support the growth and element uptake of corn and cucumber seedlings was investigated. Either dry and ground biosolids or cucumber crop residues were extracted and mineralized for five days in aerated water before the extraction solution was used as a growth medium for hydroponic plant seedlings. A control treatment was supplied with a standard nutrient solution prepared from mineral fertilizer salts. The results revealed that all tested solutions well supported the growth of the seedlings. The solution prepared from biosolids was superior to the one deriving from cucumber leaves. Cucumber plants growing on the biosolid solution grew even better than those on the standard mineral nutrient solution. Corn plants performed best on the standard nutrient solution and the least on the one prepared from cucumber leaves. The results of this study suggest that recycling nutritional elements from organic waste materials into vii hydroponic plant production systems is well possible, using a relatively simple and cheap extraction procedure that could easily be upscaled. Biosolids might be particularly suitable in this respect, and hydroponic plant production might be a feasible way of valorizing this material, which is currently largely dumped into landfills.
Said Al Nuaimi, Noura Said Al Nuaimi, "EVALUATION OF NUTRIENT SOLUTIONS PRODUCED FROM AQUEOUS EXTRACTS AND DECOMPOSITION PRODUCTS OF ORGANIC WASTE MATERIALS ON THE PLANT GROWTH PERFORMANCE IN HYDROPONICS" (2021). Theses. 871.