Agricultural Engineering and Land Planning Collection

Permanent URI for this collectionhttp://10.10.97.169:4000/handle/123456789/31

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Browsing Agricultural Engineering and Land Planning Collection by Subject "Climate change"

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    Impacts of climate change on agriculture: What, when, where and how?
    (2015) Tumbo, Siza; Sanga, C
    One of the key messages emerging out of the recent IPCC reports is that the climate change is real, happening and will continue to happen for the foreseeable future. The report also estimates with high confidence that the negative impacts on agriculture outweigh the positives which makes adaptation an urgent and pressing challenge. However, adaptation planning requires accurate information about where, when and how the impacts are going to be felt and who will be more vulnerable. Eastern Africa is considered as one of the most vulnerable regions in the world due to its high dependence on agriculture for subsistence, employment and income. Generally the region experiences prolonged and highly destructive droughts covering large areas at least once every decade and more localized events more frequently. The negative impacts of climate are not limited to the years with extreme climatic conditions. Even with normal rainfall, the countries in the region do not produce enough food to meet their needs. Overlaid on this challenging scenario is the dominance of semi-arid to arid climatic conditions which are marginal for crop production, degraded soils, extreme poverty and lack of infrastructure which make the countries in the region highly vulnerable to current and future changes in climate. There is a rapidly growing literature on vulnerability and adaptation to increased climatic variability and change but most of these assessments are based on statistical and empirical models that fail to account the full range of complex interactions and their effects on agricultural systems. For developing and implementing adaptation programs, more detailed information about how the components of the prevailing farming system such as which crops and varieties are more vulnerable and which management practices are unviable under the predicted climates is needed. However, several problems such as non-availability of downscaled local level climate change projections, lack of information on how the projected changes impact agricultural systems and scarcity of information on how these changes on production and productivity of agriculture translate into economic impacts including food security at household and national levels are constraining such an assessment.
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    Investigation of sorghum yield response to variable and changing climatic conditions in semi-arid central Tanzania: Evaluating crop simulation model applications
    (2013) Msongaleli, B.; Rwehumbiza, F. B. R.; Tumbo, S. D.; Kihupi, N.
    Combination of global circulation models (GCMs), local-scale climate variability and crop simulation models were used to investigate rain-fed sorghum yield response under current and future climate in central Tanzania. Decision Support System for Agrotechnology Transfer (DSSAT) v.4.5 and Agricultural Production Systems Simulator (APSIM) v 7.4 were calibrated and evaluated to simulate sorghum (Sorghum Bicolor L. Moench) var. Tegemeo in 2050s compared to baseline. Simulated median yields from both crop models for the baseline (1980-2010) agree with the trend of yield over the years realistically. The models predicted yields of sorghum in the range from 818 to 930 kg ha-1 which are close to the current national average of 1000 kg ha-1. Simulations by both models using downscaled weather data from two GCMs (CCSM4 and CSIRO-MK3) under the Fifth Coupled Model Intercomparison Project (CMIP5) and Representative Concentration Pathway (RCP 4.5) by mid-century show a general increase in median sorghum yields. Median sorghum yields will increase by 1.1% - 7.0% under CCSM4 and by 4.0% - 12.5% under CSIRO-MK3. Simulations for both current and future periods were run based on the present technology, current varieties and current agronomy packages. This examination of impacts of climate change revealed that increase in sorghum yield will occur despite further projected declines or increase in rainfall and rise in temperature. Modifying management practices through adjustment of sowing dates and the choice of cultivars between improved and local are seemingly feasible options under future climate scenarios depending on the GCM and the direction of the management practice. Our simulation results show that current improved sorghum cultivars would be resilient to projected changes in climate by 2050s, hence bolstering the evidence of heat and drought tolerance in sorghum crop, thus justifying its precedence as an adaptation crop under climate change. We conclude that despite the uncertainty in projected climate scenarios, crop simulation models are useful tools for assessing possible impacts of climate change and management practices on sorghum.
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    Sorghum yield response to changing climatic conditions in semi-arid central Tanzania: evaluating crop simulation model applicability
    (2013) Msongaleli, Barnabas; Rwehumbiza, Filbert; Tumbo, Siza D.; Kihupi, Nganga I.
    Decision Support System for Agrotechnology Transfer (DSSAT) and Agricultural Production Systems Simulator (APSIM) were calibrated and evaluated to simulate sorghum (Sorghum Bicolor L. Moench) var. Tegemeo under current and future climate in central Tanzania. Simulations for both current and future periods were run assuming present technology, current varieties and current agronomy packages to investigate rain-fed sorghum yield response. Simulations by both crop models using downscaled weather data from eight General Circulation Models (GCMs) under the Coupled Model Intercomparison Project phase 5 (CMIP5) and Representative Concentration Pathway (RCP 4.5) by mid-century show a mixture of increase and decrease in median sorghum yields. Four GCMs project yields to increase by 5% - 23.0% and one GCM show a decrease by 2% - 9%. Model simulations under the remaining three GCMs give contrasting results of increase and decrease. Adjustment of crop duration to mimic the choice of growing local cultivars versus improved cultivars seems a feasible option under future climate scenarios. Our simulation results show that current open-pollinated sorghum cultivars would be resilient to projected changes in climate by 2050s but things seem better with long duration cultivars. We conclude that crop simulation models show their applicability as tools for assessing possible impacts of climate change on sorghum due to agreement in the direction of crop yield predictions in five out of eight selected GCMs under projected climate scenarios. The findings provide useful guidance and motivation to government authorities and development agencies dealing with food security issues to prioritize adaptations policies geared to ensuring increased and sustained sorghum productivity in Tanzania and elsewhere.