Browsing by Author "Katushabe, Alice Amoding"
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Item Cattle Urine as a Fertiliser: Micro-biochemical Changes in Fermenting Cattle Urine and Implications on Plant Nutrient Conservation(Microbiology Research Journal International, 2015) Kilande, Geroge; Tenywa, John Stephen; Rwakaikara-Silver, Mary Christine; Katushabe, Alice AmodingAim: The aim of this study was to evaluate the microbial and biochemical changes in fermenting urine, a practice used by farmers in Sub-Saharan Africa before its application as a soil fertility input. Methodology: Two 5-litre sterile plastic containers, with a closable ends were each filled with fresh urine to capacity. One container was closed and the other left open. The set-up was replicated three times. Twenty millitres of fresh urine was taken from the bulk collection for microbial and chemical analysis. Urine samples were also taken and analysed at 4-day fermentation intervals till 24 days. Results: Fresh urine had pH=8.2 and contained Aspergillus spp. and Escherichia coli, with the latter being dominant. After 12 days of fermentation, Penicillium spp. and Pseudomonas spp. emerged and progressively increased, especially under the closed system. Whereas Aspergillus spp. counts increased in both systems, E. coli counts dropped dramatically and eventually disappeared at 16 days. The pH in the open system surged to 9.7, while that of the closed containers remained nearly stable (8.2). Organic N was not significantly (p>0.05) affected by closure of the containers. In the open system, Organic N concentration dropped up to 72%. However, NH4-N concentration increased steadily in the closed system until day 24; but dropped dramatically in the open system. Nitrate concentration increased slightly up to day 8, and thereafter, declined sharply by 97% in the open system. Similarly, in the closed system, this N species dwindled progressively but not to extinction. Conclusion: There is a shift in microbial communities in urine from Aspergillus spp. and Escherichia coli in fresh urine to Penicillium spp. and Pseudomonas spp. 12 days after the onset of fermentation. Nitrate-N is favoured by the open system, while the ammonium-N increased more in the closed system.Item Reaction of Ferralsol to Acidifying Effect of Nitrogen Fertilisation(Journal of Agricultural Chemistry and Environment, 2021) Tenywa, John Stephen; Ngarukiyimana, Jean Bosco; Katushabe, Alice AmodingBackground: The objective of this study was to determine the short-term effect of urea fertiliser application on soil reactions in a Ferralsol, with particular thrust on P sorption. Methods: Two experiments were conducted for this purpose: 1) a screenhouse pot experiment; and 2) a laboratory P sorption component. The pot (10 litre capacity plastic pots) experiment was conducted at the Makerere University Agricultural Research, Kabanyolo in Uganda, using a Ferralsol. The study comprised of four urea N (46% N) fertiliser treatments, namely, 0, 40, 80 and 120 kg N·ha-1, equivalent to 0, 200, 400 and 600 mg N per pot. A completely randomised design was adopted with three replicates. Urea rates were applied in 50% split doses, one at planting and the other at 19 days after seedling emergence (to simulate farmer practice). This was followed by watering to field capacity using distilled water. Soil samples were taken at three daily intervals until day fourteen; thereafter, soil sampling was at an interval of seven days. The second urea split dose was applied at 21 days followed by soil sampling at an interval of three days till day fourteen. Thereafter, soil was sampled at seven day intervals until the end of experiment. Soil samples were analysed for exchangeable H+, Al3+, NH4+and NO3- ions. The reaction trends of the concentrations of these ions and Bray 1 P were used to structure different response curves representing the instantaneous reactions. As for the laboratory P-sorption study, treatments included the four rates of urea used in the pot experiment (0, 40, 80 and 120 kg N·ha-1) and seven levels of P (2.5, 5, 10, 20, 30, 40 and 50 ppm) as KH2PO4. The setup was incubated under laboratory conditions and soil samples were repeatedly taken at 10 days (after 4 days of urea incubation plus 6 days of P application). The P sorption data were fitted to Langmuir model. Results: The pot experiment revealed an abrupt drop in the concentrations of exchangeable Al3+ and H+ ions (p < 0.05) within the first 6 days after urea application, accompanied by a positive surge in the concentration of NH4+ ions. This phase (6 days) was followed by a rise in the levels of exchangeable Al3+, H+ and NO3- ion concentration, which was inversely mirrored by a drop in the concentration of NH4+ ions. Consequently, the patterns displayed by the soil reactions were delineated into four phases, with Phase 1 (6 days) being characterised by urea hydrolysis reactions of deamination and ammonification, Phase 2 (10 days) being dominated by nitrification and its acidifying properties, Phase 3 being a repeat of Phase 1, both occurring immediately after urea application (within 6 days); and Phase 4 being a repeat of Phase 2. As for the P-sorption study, the effects of urea hydrolysis in a Ferralsol markedly increased soil pH and surprisingly P sorption. The contradictory P sorption behavior, despite the drop in exchange acidity was attributed to presence of divalent calcium in the extraction reagent used. Conclusion: The short term insights obtained in response to urea N application in the Ferralsol, are eye openers to future use of N fertilisers as well as strategic management of the associated acidification process which is often more costly and complicated to manage.