NRU :: Browsing by Author "Mubiru, Drake N."

Browsing by Author "Mubiru, Drake N."

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Climate change and adaptation options in Karamoja
(Organ: Food Agric, 2010) Mubiru, Drake N.
Agriculture is the backbone of the Uganda’s economy and the livelihood of many people. However, most of the agriculture in Uganda depends on rainfall and therefore inherently sensitive to climate conditions. This makes agriculture one of the most vulnerable sectors to the risks and impacts of climate change and variability. It is projected that crop yields from rain-fed agriculture in some countries in Africa could be reduced by up to 50% by 2020 as a result of climate change. Natural resources constitute the primary source of livelihood for the majority of Ugandans and the economy of Uganda depends on exploiting its natural resources. Management of these natural resources is therefore important and critical to Uganda’s long-term development. Climate is a key determinant of the status of Uganda’s natural resources, such as agriculture, forestry, water resources, wildlife, etc. However, climate change, which has started manifesting itself through intense and frequent extreme weather events, is posing a serious threat to the country’s natural resources, and social and economic development. The impacts of climate change create challenges and impose severe losses and hardships on the poorest communities as their livelihoods are likely to be more sensitive to adverse impacts of climate change. The most dominant and widespread disaster due to climate change is drought, whose frequency is observed to be on the increase. Drought has severely affected the agricultural sector leading to impacts such as famine, malnutrition, low production and productivity of crops and animals, etc. Although all the agro-ecological zones of Uganda are grappling with the effects of climate change and variability, the Karamoja sub region is most affected. This is attributable to the fact that it is the least socially and economically developed in Uganda, even among the generally poorer parts of northern Uganda as a whole. It is characterized by a combination of acute poverty, vulnerability to drought, poor infrastructure and basic services delivery, limited marketing opportunities, natural resource degradation, social and cultural marginalization, long-standing dependency on external aid and most importantly chronic insecurity.
Climate trends, risks and coping strategies in smallholder farming systems in Uganda
(Climate Risk Management, 2018) Mubiru, Drake N.; Radeny, Maren; Kyazze, Florence B.; Zziwa, Ahamada; Lwasa, James; Kinyangi, James; Mungai, Catherine
Smallholder farmers in Uganda face a wide range of agricultural production risks. Climate change and variability present new risks and vulnerabilities. Climate related risks such as prolonged dry seasons are becoming more frequent and intense with negative impacts on agricultural livelihoods and food security. This paper examines farmers’ perceptions of climate change, climate-related risks affecting crop and livestock production, including climate-risk management and adaptation strategies. Drought, increasing disease and pest incidences, decreasing water sources, lack of pasture, bush fires, hailstorms, changes in crop flowering and fruiting times were the major climate-related risks reported. In order to cope with climate change and climate variability, farmers use a wide range of agricultural technologies and strategies. Mulching, intercropping and planting of food security crops were among the most commonly used practices. Other strategies included water harvesting (mainly for domestic consumption), other soil and water conservation technologies and on-farm diversification. Farmers often use a combination of these technologies and practices to enhance agricultural productivity. Average maximum temperatures increased across the two sites. Trends in average annual rainfall showed mixed results, where a general decline was observed in one district and a relatively stable trend in the other district. Perceived changes in climate included erratic rainfall onset and cessation (which were either early or late), poor seasonal distribution of rainfall and little rainfall. In addition, farmers reported variations in temperatures. Farmers’ perception of changing rainfall characteristics and increasing temperatures were consistent with observed historical climatic trends based on meteorological data.
Conservation Farming and Changing Climate: More Beneficial than Conventional Methods for Degraded Ugandan Soils
(Sustainability, 2017) Mubiru, Drake N.; Namakula, Jalia; Lwasa, James; Otim, Godfrey A.; Kashagama, Joselyn; Nakafeero, Milly; Nanyeenya, William; Coyne, Mark S.
The extent of land affected by degradation in Uganda ranges from 20% in relatively flat and vegetation-covered areas to 90% in the eastern and southwestern highlands. Land degradation has adversely affected smallholder agro-ecosystems including direct damage and loss of critical ecosystem services such as agricultural land/soil and biodiversity. This study evaluated the extent of bare grounds in Nakasongola, one of the districts in the Cattle Corridor of Uganda and the yield responses of maize (Zea mays) and common bean (Phaseolus vulgaris L.) to different tillage methods in the district. Bare ground was determined by a supervised multi-band satellite image classification using the Maximum Likelihood Classifier (MLC). Field trials on maize and bean grain yield responses to tillage practices used a randomized complete block design with three replications, evaluating conventional farmer practice (CFP); permanent planting basins (PPB); and rip lines, with or without fertilizer in maize and bean rotations. Bare ground coverage in the Nakasongola District was 187 km2 (11%) of the 1741 km2 of arable land due to extreme cases of soil compaction. All practices, whether conventional or the newly introduced conservation farming practices in combination with fertilizer increased bean and maize grain yields, albeit with minimal statistical significance in some cases. The newly introduced conservation farming tillage practices increased the bean grain yield relative to conventional practices by 41% in PPBs and 43% in rip lines. In maize, the newly introduced conservation farming tillage practices increased the grain yield by 78% on average, relative to conventional practices. Apparently, conservation farming tillage methods proved beneficial relative to conventional methods on degraded soils, with the short-term benefit of increasing land productivity leading to better harvests and food security.
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.
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.

Browsing by Author "Mubiru, Drake N."

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