Browsing by Author "Otabbong, Erasmus"

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    Comparison Of Four Low-Technology Composting Methods For Market Crop Wastes
    (Waste Management,, 2009) Tumuhairwe, John Baptist; Tenywa, John Stephen; Otabbong, Erasmus; Ledin, Stig
    Four methods for composting, pit-cover (PC), pit-open (PO), above ground-open (AO) and above ground-covered (AC), were compared for their effect in accelerating compost maturity using market crop waste (MCW). The composting process was monitored through determining changes in temperature and pH, with compost maturity indices measured in terms of variations in water-soluble carbon (WSC), ammonium-N () and nitrate-N (), and C/N, , WSC/organic N and WSC/total N (TN). Total organic carbon (TOC), nitrogen (TN), potassium (TK) and phosphorus (TP) were also determined. Temperature rapidly increased from mesophilic to thermophilic and gradually reduced through maturation phases. A similar pattern was recorded for pH, which reached a slightly alkaline level at maturity. Composting significantly (p < 0.05) decreased the concentrations of TOC, TN, TP, TK, and WSC and increased that of . All four low-technology composting methods used in this study produced mature composts within 63 days. Suitable maturity indicators for MCW compost were C/N ratio < 12, WSC < 1%, < 400 mg kg−1, / < 0.2, WSC/TN, WSC/organic-N < 1. On the basis of these indicators, the AC method generally enhanced maturity faster than the AO, PC and PO methods. Pit methods require less investment and are recommended for the smallhold farmers.
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    Development of Common Bean (Phaseolus Vulgaris L.) Production Under Low Soil Phosphorus and Drought in Sub-Saharan Africa: A Review
    (Journal of Sustainable Development, 2013) Margaret, Namugwanya; Tenywa, John Stephen; Otabbong, Erasmus; Mubiru, Drake N.; Basamba, Twaha Ali
    Owing to its nutritional value, especially proteins, carbohydrates, vitamins and micronutrients, common bean (Phaseolus Vulgaris L.) has been recognised as a crop that could ensure food security mostly, in Sub-Saharan Africa, where its productivity is low. Its low productivity is attributed to a milliard of constraints, of which low plant-available phosphorus (P) and limited moisture in soil are among the major limiting factors. Synergistic effects of the two factors are accentuated in Sub-Saharan African region. This paper discloses the importance of the synergistic effects of plant-available P and moisture in soils on common bean production. It has been observed that studies investigating impacts of interactions of low P levels and moisture deficit conditions in soils are yet to be conducted. Identification of traits that contribute to high performance under low P availability and moisture deficit in the same genotypes remains a major research and development challenge. However, engineering new genotypes alone may not alleviate the problem of ensuring improvement of high bean yields. Root architecture and root exploration of the soil that enable the plant to access the two soil resources, traditional methods that preserve good status of organic matter in soils and moisture and soil preparation techniques are equally important. This, calls for holistic investigations that include soil plant-available P and moisture, common bean genotypes and their root systems, and agronomic measures to facilitate a comprehensive evaluation of impacts of deficiencies in soils on common bean yields. This paper explores and synthesizes existing research and development of common bean grown in soils deficient in plant-available P and moisture, aiming at designing future research to enhance common bean productivity.
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    Effectiveness of crop-waste compost on a Eutric Ferralsol
    (Journal of Plant Nutrition and Soil Science, 2011) Amoding, Alice; Tenywa, John Stephen; Ledin, Stig; Otabbong, Erasmus
    Lack of environmentally safe handling of garbage is a growing problem in urban sub-Saharan Africa (SSA). Composting the garbage for soil-fertility management presents an opportunity for reducing the risks of environmental pollution. This study aimed at evaluating the agronomic effectiveness and nutrient-utilization efficiency of urban market crop-waste compost on a Eutric Ferralsol. The study was conducted in central Uganda with treatments including compost applied at 0, 5, and 10 t ha–1 (d.w. basis); inorganic N fertilizer at rates of 0, 40, and 80 kg ha–1 and inorganic P fertilizer at 0, 9, and 18 kg ha–1. Maize (Zea mays L.), variety Longe 4 was used as the test crop. The nutrient quality of the compost was medium with total N of 0.9% and total P of 0.45%. Compost significantly increased plant height, LAI, stover weight, and grain yield; however, there were no significant differences between the 5 and 10 t ha–1 rates. Nitrogen also had a significant effect on LAI and stover yield, though there was no significant difference between the 40 and 80 kg ha–1 rates. Likewise, P increased plant height with no significant difference between the 9 and 18 kg ha–1 rates. Mineral N at 40 kg ha–1 led to the highest increase in N uptake by plants (76%) above the control. Nitrogen- and P-utilization efficiencies for the 5 t ha–1 compost rate were more than twice that of the 10 t ha–1 rate. The highest P-utilization efficiency (69%) was obtained where 9 kg ha–1 P was applied with 40 kg ha–1 N, while the highest N-utilization efficiency (48%) was obtained with the 5 t ha–1 compost applied together with N at 40 kg ha–1. From the above studies, it is clear that effectiveness of the 5 t ha–1 compost rate is the most promising.