NRU :: Browsing by Author "Tenywa, John Stephen"

Browsing by Author "Tenywa, John Stephen"

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Adaptation of RUSLE to Model Erosion Risk in a Watershed with Terrain Heterogeneity
(International Journal of Advanced Earth Science and Engineering, 2013) Luliro, Nadhomi Daniel; Tenywa, John Stephen; Majaliwa, Jackson Gilbert Mwanjalolo
The modeling capability of the Revised Universal Soil Loss Equation (RUSLE) on a heterogeneous landscape is usually limited due to computational challenges of slope length and slope steepness (LS) factor. RUSLE can be adapted to Arc-Macro (C++) executable programs to obtain LS values even for highly variable landscapes based on Digital Elevation Models (DEMs); and then predict erosion risk. The objective of this study was to compute LS factor from DEM using C++; and predict soil erosion risk in a banana-coffee watershed of the Lake Victoria Basin (LVB) of Uganda. DEM data of Nabajuzi watershed were used as an input file for running the (C++) executable program to obtain LS factor. The predicted LS values were calibrated against tabulated LS values; and a strong linear relationship (R = 0.998) was observed between them. The LS factor increased with slope length and slope gradient. Erosion risk across landuse were predicted as follows: small scale farmland (38 t ha-1 yr-1 ), built up area (35 t ha-1 yr-1 ), grassland (25 t ha-1 yr-1 ), woodland (11 t ha1 yr-1 ), shrub land and seasonal wetland (2.5 t ha-1 yr-1 ), permanent wetland (0 t ha-1 yr-1 ). While across soil units erosion risk was highest on Lixic Ferralsols (50 t ha-1 yr-1 ), followed by Acric Ferralsols (20 t ha-1 yr-1 ), Arenosols (15 t ha-1 yr-1 ), Gleyic Arenosols (2.5 t ha-1 yr-1 ), and Planosols (0 t ha-1 yr-1 ). The risk of erosion increased linearly with slope gradient in the site (R = 0.96). On the steepest slopes (15-18) %, the loss ranged from (38–68) t ha-1 yr-1 and on lowest slopes (0-5) %, the loss was (0–2.5) t ha-1 yr-1 . We conclude that embedding C++ with GIS data derives LS factor from DEMs. It provides a bench mark for understanding slope morphology; hence making erosion risk prediction on nonuniform slopes much easier.
Bacterial community changes during composting of municipal crop waste using low technology methods as revealed by 16S rRNA1* and Department
(African Journal of Environmental Science and Technology, 2018) Tumuhairwe, John Baptist; Tenywa, John Stephen
Bacterial communities are actively involved in composting process but the environment within the compost influences their diversity, abundance and succession. In this study, the authors investigated the bacterial communities in tropical crop waste compost using pyrosequencing. Municipal crop wastes from the tropics (Uganda) were composted under four different low-technology methods. Samples were collected from the early thermophilic, late thermophilic, and mesophilic phases, and from mature compost. Pyrosequencing of the amplified variable V4 region of the 16s rDNA generated over 110 000 sequences. Chao1 and cluster analysis at 3% dissimilarity showed that bacterial community richness declined during the composting process. The community was dominated by a few bacterial taxa during the thermophilic phases. Species evenness increased as compost progressed to maturity despite a decline in the number of taxa over the successional progression. Bacterial community diversity, abundance and succession changed with the composting method. This pattern of diversity may be attributed to competition and selection during the microbial succession. A total of 22 phyla and 513 genera were identified from all the methods in the entire composting process. The most abundant phyla were Proteobacteria, Firmicutes, Bacteriodes and Actinobacteria. Pyrosequencing provided more information on compost bacterial community diversity and abundance than previously used molecular methods. Several novel bacteria existing in tropical crop waste compost remained unclassified.
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 Amoding
Aim: 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.
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.
Critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol
(Experimental Agriculture, 2016) Musinguzi, Patrick; Ebanyat, Peter; Tenywa, John Stephen; Basamba, Twaha Ali; Tenywa, Moses Makooma; Mubiru, Drake N.
Soil Organic Carbon (SOC) is a major indicator of soil fertility in the tropics and underlies variability in crop response to mineral fertilizers. Critical SOC concentrations that interact positively with N fertilizer for optimal crop yield are less understood. A study was conducted on a Ferralsol in sub-humid Uganda to explore the critical range of SOC concentrations and associated fractions for optimal maize (Zea mays L.) yield response to applied mineral N fertiliser. Maize grain yield response to N rates applied at 0, 25, 50 and 100 kg N ha−1 in 30 fields of low fertility (SOC < 1.2%), medium fertility (SOC = 1.2–1.7%) and high fertility (SOC > 1.7%) was assessed. Soil was physically fractionated into sand-sized (63–2000 µm), silt-sized (2–63 µm) and clay-sized (<2 µm) particles and SOC content determined. Low fertility fields (<1.2% SOC) resulted in the lowest response to N application. Fields with >1.2% SOC registered the highest agronomic efficiency (AE) and grain yield. Non-linear regression models predicted critical SOC for optimal yields to be 2.204% at the 50 kg N ha−1 rate. Overall, models predicted 1.9–2.2% SOC as the critical concentration range for high yields. The critical range of SOC concentrations corresponded to 3.5–5.0 g kg−1 sand-sized C and 9–11 g kg−1 for clay-sized C.
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.
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.
Heavy Metal Bioaccumulation by Maize Grown on a Ferralsol Amended with Urban-Based Biosolid Wastes
(Journal of Agricultural Chemistry and Environment, 2021) Ntambi, Emmanuel; Ntale, Muhammad; Tenywa, John Stephen
Organic waste materials as soil amendments are one of the topical approaches applauded for achieving sustainable agriculture world-over. The objective of this study was to investigate the effect of urban-based biosolid waste (UBBW) application on heavy metals (Cr, Cu, Zn and Pb) bioaccumulation by maize (Zea mays L.) plants. A pot experiment was conducted three times, using an acid Ferralsol from Makerere University Agricultural Research Institute, Kabanyolo (MUARIK) in Uganda. Treatments included the application of three types of UBBW, namely sewage, brewery and abattoir, each applied independently at the rates of 0, 50 and 100 g per pot filled with 4 kg soil. This was equivalent to 0, 2.5 and 5.0 metric tonnes of dry materials per hectare. Phosphorus fertiliser was also applied at 0, 0.795 and 1.591 g P per pot, equivalent to rates of 0, 25 and 50 kg P ha-1. The brewery waste applied at rates ≥ 2.5 t·ha-1 and phosphorus at 25 kg P ha-1 resulted in shoot Cu concentrations below the World Health Organisation (WHO) safe limit (73.3 mg·kg-1); and Zn slightly above the WHO safe limit (99.4 mg·kg-1). In contrast, the concentrations of chromium in the maize plants were well above the WHO safe limit (2.3 mg·kg-1), irrespective of the applied type of UBBW. Shoot metal bioaccumulation followed the order zinc > copper > chromium, with Pb being below the detection limit. The safest UBBW was abattoir waste; while the least environmentally suitable was sewage waste. It is clear that irrespective of the type of UBBW, their application to Ferralsol causes less bioaccumulation of Pb and Cr in maize plants compared to Zn and Cu.
Nitrogen-neutrality: a step towards sustainability
(Environmental Research Letters, 2014) Leip, Adrian; Leach, Allison; Musinguzi, Patrick; Tumwesigye, Trust; Olupot, Giregon; Tenywa, John Stephen; Mudiope, Joseph; Hutton, Olivia; Cordovil, Claudia M d S; Bekunda, Mateete
We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, N-neutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US$ 3050 was collected from the participants and used to offset the conference's N footprint by supporting the UN Millennium Village cluster Ruhiira in South-Western Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates.
Reaction of Ferralsol to Acidifying Effect of Nitrogen Fertilisation
(Journal of Agricultural Chemistry and Environment, 2021) Tenywa, John Stephen; Ngarukiyimana, Jean Bosco; Katushabe, Alice Amoding
Background: 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.
Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects
(concepts and prospects., 2013) Musinguzi, Patrick; Tenywa, John Stephen; Ebanyat, Peter; Tenywa, Moses Makooma; Mubiru, Drake N.; Basamba, Twaha Ali; Leip, Adrian
Soil organic carbon (SOC) is a potential soil fertility indicator for regulating nitrogen application in tropical farming systems. However, there are limited studies that have discussed SOC thresholds above or below which crop production could be diminished, or at which no or high response to nitrogen (N) application can be realized. This review explores the drivers of SOC concentration relevant for the establishment of thresholds. We further evaluate existing SOC thresholds for provoking no yield response or significant response to added N fertilizer. Key drivers for SOC concentration relevant in establishing thresholds are mainly climate, topography, texture, and land use management. Soil organic carbon threshold for sustaining soil quality is widely suggested to be about 2% below which deterioration may occur. For added N fertilizer management, specific SOC thresholds seem quite complex and are only valid after assuming other factors are non-limiting. In some soils, SOC levels as low as 0.5% result in fertilizer responses and soils as high as 2% SOC also respond to small N doses. Minimum SOC thresholds can be identified for a given soil type, but maximum thresholds depend on crop N requirements, crop N use efficiency and amount of N applied. However, there seem to exist critical total SOC ranges that could be targeted for optimal indigenous N supply and integrative soil functional benefits. These can be targeted as minimum levels in soil fertility restoration. In all, it is still difficult to establish a single minimum or maximum SOC threshold value that can be universally or regionally accepted
Soil organic fractions in cultivated and uncultivated Ferralsols in Uganda
(Geoderma Regional, 2015) Musinguzi, Patrick; Tenywa, John Stephen; Ebanyat, Peter; Basamba, Twaha Ali; Tenywa, Moses Makooma; Mubiru, Drake N.; Zinn, Yuri L.
Ferralsols are chemically poor soils, with management challenges associated with soil fertility heterogeneity and nitrogen limitations. Proper assessment of soil organic matter fractions can be instrumental in understanding the causes of limited nitrogen supply, and thus addressing soil fertility heterogeneity. A study was conducted in cultivated and uncultivated Ferralsols, in order to assay soil organic carbon (SOC), its particle-size fractions and their influence on soil fertility heterogeneity across small farms in central Uganda. Soil samples were taken from the 0–15 and 15–30 cm depths from 30 cultivated fields classified as of low fertility, medium fertility and high fertility, and from two nearby sites in a native shrubland as references. Soil samples were physically fractionated into sand (2000–63 μm), silt (63–2 μm) and clay (< 2 μm). Total SOC and N were analyzed in bulk samples and each size fraction, and the Carbon Management Index (CMI), a widely used indicator of soil quality, was calculated for each field. The CMI in cultivated soils was far below the 100% in reference soils, reaching 34.7, 40.3 and 87% in low, medium and high fertility fields, respectively. SOC and N concentrations decreased in particle-size separates in the order clay > silt > sand. The SOC pool and N in the clay-sized fraction were correlated to soil fertility indicators. More N was stored in the silt + clay size fractions, a generally more stable pool, than in the more labile sand-sized pool. The SOC pool in sand size fractions was far below in low and medium fertility soils than in a reference uncultivated soil. Thus, the sand-sized pool emerged as the most likely cause of limited N supply in cultivated low-input Ferralsols in Uganda.
Sustainable Land Management Paradigm: Harnessing Technologies for Nutrient and Water Management in the Great Lakes Region of Africa
(Sustainability in Natural Resources Management and Land Planning, 2021) Musinguzi, Patrick; Ebanyat, Peter; Basamba, Twaha Ali; Tumuhairwe, John Baptist; Opolot, Emmanuel; Olupot, Giregon; Tenywa, John Stephen; Mwanjalolo, Jackson Gilbert Majaliwa
Sustainable Land Management (SLM) is one of the transformative pillars for agricultural development and environment conservation for food, forage, fuel and fiber security. It aims at the tripartite benefits of high yields, environment protection and income security. The success of SLM is a function of adopting appropriate nutrient and water management practices. Several land management practices have been practiced by smallholder farms in the Great Lakes Region of Africa. However, there is still limited understanding of the level of acceptability of the various technologies in mitigating soil water shortage and nutrient depletion. This paper evaluates the SLM concept with focus on assessing sustainability in the use of various soil water and nutrient management technologies and practices. Nutrient management technologies assessed included a range of common inputs and practices in tropical farming systems. Soil water conservation technologies assessed included the physical, biological and agronomic measures. Analysis conducted suggest that few land users can afford to adopt most of the available technologies that define a full package for realization of the pillars of SLM. Integrated use of technologies remains the appropriate approach to responding to the alarming challenge of land degradation. Inclusion of social-cultural and economic factors in the application of SLM technologies of soil, water and nutrients is fundamental for increased adoption. Policies for SLM should target integrated technologies centered on people in order to achieve the ultimate goal of enhanced agricultural productivity, environment conservation and income in the Great Lakes Region of Africa.
Uptake of Knowledge and Technologies for Adaptation to Climate Change in Crop Production Systems in Uganda: A Review
(Advances in Research, 2017) Tenywa, John Stephen; Nabasirye, Margaret; Twinomuhangi, Revocatus; Mfitumukiza, David.
Knowledge and technology uptake in the context of climate change adaptation is critical in ensuring that communities vulnerable to climate risks, respond effectively with appropriate actions, and particularly to its extreme events that are increasingly bedeviling agricultural natural resources and livelihoods, especially in Sub-Saharan Africa. Uptake as a subject is either loosely treated or lightly understood by actors in the African climate change research and development continuum. The objective of this article was to appraise the status of uptake of innovations (knowledge and technologies) of climate change adaptations in crop-based systems in Uganda, and propose viable interventions for enhancing the uptake process to obviate the escalating effects of climate change and its associated variability. The study was conducted during December 2016. It was dominantly a desk review, primarily based on existing online information sources and other national institutional repositories. The other information source was from a two-days stakeholder workshop involving key actors within the climate change research and development value chain in Uganda. They validated the synthesised information and supplemented with more recent events and hitherto undocumented scenarios. The study revealed that uptake of climate change adaptation actions was measurably low in the country; hence, communities were far from ready to face the recurrently changing and increasingly aggressive climate change events. Among the major contributors to slow uptake were lack of a coherent climate change activity coordination entity in the country, to organise actors into a functional service delivery system with minimum duplication; ensuring quality actions and following a unidirectional long term goal. The other hindrances included scattered knowledge and technologies, sub-optimal communication and extension services, technology products misconception, low adaptation capacity, unfavourable policies and policy environments, ineffectiveness traditional public and civil society extension agencies. Interventions are proposed to obviate these bottlenecks, using largely internal mechanisms.
Using DSSAT-CENTURY Model to Simulate Soil Organic Carbon Dynamics Under a Low-Input Maize Cropping System
(2014) Musinguzi, Patrick; Ebanyat, Peter; Tenywa, John Stephen; Mwanjalolo, Majaliwa; Basamba, Twaha Ali; Tenywa, Moses M; Porter, Cheryl
Decline in Soil Organic Carbon (SOC) below the critical levels is one of the major indicators of soil fertility depletion in Sub-Saharan Africa (SSA), with the main causes being poor management practices coupled with low input use. Measures for monitoring long-term impacts of management on SOC dynamics and its restoration can be critical in enhancing sustainable soil productivity. Crop models have proved to be good tools for understanding the influence of management options on soil and crop productivity. The DSSAT-Century model was applied to simulate the influence of management practices on SOC dynamics. Using long-term datasets from Kabete, Kenya (1976-1996 maize-bean) and Kiboga-Uganda (1980-2010 maize), model calibration and evaluation showed a good fit between simulated and observed values of SOC. On simulating continuous tillage with no fertilization for the 1980-2010 antecedent period and 2010-2060 extrapolated period, the model showed high rates of SOC decline in the newly cultivated soil as compared to a degraded soil. The simulated rate of decline is 2129 kg ha-1 yr-1 for newly cultivated soil and 849 kg ha-1 yr-1 for the continuously cultivated soils. The model was sensitive to initial partitioning of SOC pools, with SOC in previously uncultivated soils declining at a higher rate than that in the cultivated ones. The model confirmed that use of continuous tillage is a major threat to SOC building and soil fertility restoration in the tropics. Adopting conservation agriculture is critical for future generations. Overall, the DSSAT CENTURY model is a potential tool for predicting SOC dynamics in low-input farming systems.

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