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University of Namibia (2018)

The potential of goat manure as a hydroponic nutrient alternative for tomato production in Namibia

Mowa, Edgar

Titre : The potential of goat manure as a hydroponic nutrient alternative for tomato production in Namibia

Auteur : Mowa, Edgar

Université de soutenance  : University of Namibia

Grade : Doctor of Philosophy in Agriculture (Crop Science) 2018

Hydroponics is a cultivation method of growing plants in water. It is a technology suitable for farming that is under artificially controlled environments but can be adapted to situations where land is a constraint. In Namibia this is a potential method for vegetable cultivation. Hydroponics vegetable production has been demonstrated successfully using a balanced conventional nutrient solution, globally, and therefore, an evaluation of its suitability in Namibia using goat manure solution as a source of organic hydroponic nutrients. An alternative hydroponics nutrient solution has been sought after but often failed due to nitrogen in organic sources being predominantly organic, a form plants cannot access. The study had two stages, the first being a laboratory experiment aimed at formulating a Goat Manure Derived Hydroponic Nutrient Solution (GMDHNS). This involved the determination of source of microorganisms, concentration of microorganisms and amount of goat manure for optimal generation of nitrates from goat manure. Variables measured included nitrate levels generated and levels of other nutrients. The second stage was a field experiment which tested the GMDHNS effect on tomato performance and quality. Variables measured included, plant height, stem diameter, nutrient use efficiency, plant biomass, number of flowers, number of fruits, yield, total soluble solids, and lycopene content. Commercial Hydroponic Nutrient Solution and tap water were used as controls. Locally sourced microorganisms significantly (P< 0.05) transformed organic nitrogen in goat manure into plant available nitrates reaching levels of 198mg/L hence was the basis of the organic hydroponic nutrient solution. Tomato vegetative growth (height, stem diameter and leaves) were significantly (P< 0.05) improved by the formulated GMDHNS compared to growing tomatoes in Tap Water (TW) where no fertiliser was added and that GMDHNS was comparable to using Commercial Hydroponic Nutrient Solution (CHNS) in terms of plant growth. Plant reproduction (flower and fruits) were also significantly (P< 0.05) influenced by the formulated GMDHNS more than by the TW treatment even though yield from GMDHNS was less than that from the CHNS. The quality (lycopene, Total Soluble Solids, fruit size and weight) of fruits produced from plants in the GMDHNS was significantly (P< 0.05) more than that in fruits from the CHNS. Thus, based on the results from this study, it can be concluded that a hydroponic nutrient solution can be formulated from goat manure. Furthermore, it can ii be concluded that the locally formulated hydroponic nutrient solution enhances quality, growth and reproductive performance of tomato, even though it may still need further optimization. Follow-up studies to the present study should be done to further optimise GMDHNS and that artefactual should also follow for practical uptake of these findings.


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