Efficacy of Fortified Molasses Waste-Water as Hydroponic Nutrient Solution for Growing of Spinach and Barley
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Date
2021
Authors
Jepkoech, Rael
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Muhoroni Sugar Processing Industry is a significant sugar factory in western part of
Kenya. It produces huge volumes of molasses waste-water which poses challenges of
pollution of water bodies and affects plant life and other organisms. Molasses wastewater
is known to have substantial amounts of nutrients and has been suggested as an
alternative to commercial hydroponic fertilizers. However, its efficacy as a nutrient
solution has not been evaluated scientifically. This study therefore aimed at
investigating its efficacy as a hydroponic solution for growing vegetables and fodder
crops in a greenhouse. Greenhouse experiments were carried at the Christian Industrial
Training Centre – Kapsabet in Nandi County (0.2030° N, 35.0978°). Macro-nutrients
present in molasses waste-water were determined and the deficiencies remedied by
fortifying with appropriate amounts of nitrogen, phosphorous and potassium (NPK)
fertilizer. The standard Walkey black rapid titration was used to determine total organic
carbon. Potassium and calcium were determined using flame photometry. Nitrogen and
phosphorous were determined by colorimetric analysis. Magnesium was analysed using
atomic absorption spectroscopy. Uv/vis spectrophotometry was used to determine the
presence of sulphur.The study established that molasses waste-water has greater levels
of potassium, calcium, sulphur, magnesium and carbon of 230.0 ± 1.00 mg/L, 25.9 ±
0.39 mg/L, 4.4±0.07 mg/L, 0.04 ± 0.01 mg/L and 37.3 ± 0.67%, respectively compared
to commercial hydroponic nutrient solutions. Low nitrogen and phosphorus content in
molasses waste-water was improved to 74.3 ± 0.18 and 47.6 ± 0.01 mg/ L, respectively.
The greenhouse experiments were set up in triplicate using a Complete Randomized
Block Design (CRBD). The hydroponic nutrient solutions used included molasses
waste-water (MW) and fortified molasses waste-water (FMW) with commercial
hydroponic nutrient solution (HN) as the control experiment. Barley was grown by
improvised nutrient film (NFT) technique whereas spinach was grown in static solution
culture using sand growing media. Plant growth parameters which include plant height,
stem girth and leaf length were measured every after 2 days in barley and every after 7
days in spinach. The levels of macro-nutrients in plant tissues were determined in the
harvested crops. The plants grown in fortified molasses waste-water showed the highest
growth parameters; mean plant height of 13.0± 0.38cm, mean stem girth of 9.23 ± 0.43
mm and mean leaf length of 5.6±0.17cm in barley, mean plant height of 20.97 ± 0.18
cm, mean stem girth of 16.2±0.12 cm and mean leaf length of 13.0±0.38 cm in spinach.
Mean fresh weight of 0.6±0.06 kg for spinach and 12.0 ± 0.57 kg for barley grown in
fortified was obtained. Crops grown in fortified molasses waste-water also recorded the
highest values of macro-nutrients at 210.6± 0.07 and 205.9 ± 0.14 mg/kg nitrogen, 94.9
± 0.01 and 90.7± 5.79 mg/kg phosphorus, 3.3 ± 0.05 and 6.4 ± 0.01mg/kg magnesium,
632.7± 7.54 and 616.5± 2.30 mg/kg potassium, 48.8±0.71 and 38.0±0.34 mg/kg
calcium and 15.8±0.04 and 15.8±0.05 mg/kg sulphur in spinach and barley,
respectively. Organic carbon content was also highest in spinach and barley grown in
fortified molasses waste-water at 84.0 ± 1.15 and 82.7 ± 0.67% respectively. The results
show that molasses waste-water contains adequate amounts of potassium, calcium,
sulphur and magnesium macro-nutrients essential for plant growth but lacks sufficient
nitrogen and phosphorus. Appropriate amendments in the amounts nitrogen and
phosphorus macro-nutrients make it efficacious for application as a hydroponic solution
for growing crops and, therefore, a possible alternative to commercial hydroponic
nutrient solution.
Description
A thesis Submitted in Partial Fulfillment of the Requirements for the award of the Degree of Master of Science (Analytical Chemistry) in the School of Pure and Applied Sciences of Kenyatta University, May 2021
Keywords
Efficacy, Fortified Molasses Waste-Water, Hydroponic Nutrient Solution, Growing, Spinach, Barley