Climate Change and Agriculture - Batch 4

Modeling of Climate Change Impacts on Sorghum Yield under Different Inputs and Management Practices in Mali

2026-07-21T14:10:50Z

Modeling of Climate Change Impacts on Sorghum Yield under Different Inputs and Management Practices in Mali Bolozogola, Youssouf Sorghum (Sorghum bicolor (L.) Moench) is one of the most important crops for human food and animal feeding worldwide. In Mali, sorghum is a vital cereal crop for food security. Despite its importance in the country’s food security, average farmer yield of sorghum remains low (less than 1 t ha-1). Climate variability and change, poor soil fertility, limited improved seeds adoption, and management practices are major factors of this low productivity. The objective of this thesis was to evaluate through experimentation and modelling approaches, the effects of management practices (sowing dates and fertilizer types) on improved sorghum cultivars to enhance the adaptive capacity of farmers on sorghum production in Mali Sudano-Sahelian zone. Experiments were conducted at Samanko, N’Tarla and Cinzana during the 2021 and 2022 growing seasons. In each site, a split-split plot design was used as experimental design with four fertilization types [F1 (the control, no fertilization); F2 (the mineral recommended fertilization rate for sorghum and millet production in Mali, 100 kg ha-1 DAP + 50 kg ha-1 urea); F3 (the organic amendment rate in Mali, 5000 kg ha-1 cow dung); and F4 (the combined option made of half doses of F2 and F3, ie., 50 kg ha-1 DAP + 25 kg ha-1 urea + 2500 kg ha-1 cow dung)] as main factor, two sowing dates (SWD1 and SWD2, medium-early and late sowing dates, respectively) as subfactor and three sorghum varieties (Soubatimi, Jakunbe and Pablo) as sub-sub factor, replicated three times. Days to 50% flowering, plant leaves number at 50% flowering, plant height at harvest, panicle length at harvest, mean weight of 100 grains, aboveground biomasses at 50% flowering and at harvest, grain yield and water use efficiency of grain yield (WUE_GY) were evaluated. From the two cropping seasons trials, DSSAT/CERES-Sorghum model was calibrated with the F2 data and validated with the three other fertilizer types (F1, F3 and F4) data. After validation, seasonal simulation analyses on 31 years (1990-2020) were performed to evaluate the effect of management practices [different fertilization strategies (F1, F2, F3 and F4), and varying sowing windows (early sowing window, SW1 from 1st to 20th of June; medium sowing window, SW2 from 21st of June to 10th of July; and late sowing window, SW3 from 11th to 30th July)] on grain yield, and WUE of the three calibrated cultivars across agroecological zones (Samanko for the Southern Sudanian zone, N’Tarla for the Northern Sudanian zone, and Cinzana for the Southern Sahelian zone). Results concerning the thesis agronomic aspects revealed that experiments sites soil nitrogen and phosphorus contents were low, and the rainfall was also variable during the growing seasons in the study agroecological zones. These environmental factors had different effects on the growth and development of the tested varieties. Moreover, analyses of variance (ANOVA) of trials data showed that days to 50% flowering for the three varieties was mostly shortened under the organo-mineral fertilization F4 compared to the three other fertilizer types at Samanko and N’Tarla. First sowing date (SWD1) and organo-mineral fertilization have considerably increased growth parameters like plant leaves number at 50% flowering and plant height at harvest at Samanko. Likewise, results revealed that SWD1 produced higher biomass and grain yield, as well as higher WUE, compared to SWD2 (the second sowing date) at Samanko during both seasons. SWD1 outperformed SWD2 for biomass and grain yield, with increases of 65% and 30%, respectively. The organo-mineral fertilization F4 recorded the highest biomass and grain yield and the highest WUE compared to other fertilization types. During both cropping seasons, the hybrid Pablo produced the highest biomass (4083 and 6795 kg ha-1) and grain yield (1765 and 2740 kg ha-1), as well as the highest water WUE (3.83 and 6.15 kg ha-1 mm-1) at Samanko while the variety Soubatimi produced the highest biomass (6171 and 7085 kg ha-1) at N’Tarla. Regarding the study modelling aspects, the calibration and validation processes gave satisfying results with good agreements between simulated and observed values for phenology (anthesis and maturity dates), leaves number, aboveground biomass and grain yield. Long-term management practices’ simulations (fertilization strategies, and sowing windows) indicated that optimized nitrogen fertilizer application (mineral or organo-mineral) and early sowing window, applied alone or in combination, could substantially increase sorghum yields under current climate conditions in Mali Soudano-Sahelian region. In conclusion, this study highlights the value of crop simulation models for identifying and promoting effective management strategies, such as optimized organo-mineral fertilization and adjusted sowing dates to enhance sorghum production and bolster food security in the Soudano-Sahelian region, providing actionable insights for farmers and policymakers. A thesis, in the Rural Polytechnic Institute of Training and Applied Research (IPR/IFRA) in partnership with the West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL), submitted in partial fulfilment of the requirements for the Doctor of Philosophy in Climate Change and Agriculture of the University of Sciences, Techniques and Technologies of Bamako (USTTB)

Field Experimental and Modelling Assessment of The Effects of Different Water Management and N-Fertilizer Levels on Co2 Emissions, Net Ecosystem Carbon Balance and Rice Production

2026-07-21T13:52:26Z

Field Experimental and Modelling Assessment of The Effects of Different Water Management and N-Fertilizer Levels on Co2 Emissions, Net Ecosystem Carbon Balance and Rice Production Sossa, Coffi Leonce Geofroy Accurate measurement of carbon dioxide ( CO 2 ) emissions and water H 2 O ) fluxes is crucial for reducing global greenhouse gas (GHG) emissions and mitigating climate change, especially in agricultural land systems. To explore effective ways to improve rice production in Benin while protecting the environment, an adaptive, low cost, open source data logger has been developed to measure CO 2 , evapotranspiration ( ET )), and estimate the net carbon (C) balance from irrigated lowland rice cultivation in Benin. Laboratory tests and field validation on different Non Dispersive Infrared NDIR sensors showed that the K30 Fr and SCD30 sensors are the most accurate compared to the Li COR 850 IRGA. The field application aims to identify the best farming management practices that improve water and nitrogen use efficiency, grain yield, and the net ecosystem carbon balance while keeping CO 2 emissions low. It was established at Koussin Lele , southern Benin, using a split plot design where the main plot is different water management, and the subplot i s different level of nitrogen fertilizer. The water management i ncluded continuous flooding (CF) and two levels of alternate wetting and drying at 15 cm and 25 cm thresholds (AWD 15 and AWD 25 ). The different levels of nitrogen fertilizer were: no nitrogen, N 90 kg ha 1 , and N120 kg ha 1 . To measure gaseous seasonal C emissions and soil CO 2 respiration, the NFT NSS closed chamber system is used, and results showed that both net ecosystem exchange, the net C balance, and evaporation were higher under AWD 15 and C F even though all the treatments are sinks of carbon. The heterotrophic respiration was higher under AWD 25 . In terms of water productivity, grain yield, and N uptake, results showed that the treatment AWD 15 with N 90 kg ha 1 is the best. Consequently, this treatment should be promoted to reduce costs resulting from fertilizer inputs, conserve yield, and combat water scarcity. In addition, the calibration of the DSSAT CERES rice model was successful in simulating growth and yield, and the results illustrated that the model is a useful tool for evaluating alternative management options to maintain yields while saving water. As a recommendation, for further study, it could be interesting to add manure fertilizer and assess CH4 emissions from each treatment. In perspective, this study will help to make decisions regarding the C balance and the optimization of water and nitrogen inputs for sustainable irrigated rice. A thesis, in the Rural Polytechnic Institute of Training and Applied Research (IPR/IFRA) in partnership with the West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL), submitted in partial fulfilment of the requirements for the Doctor of Philosophy in Climate Change and Agriculture of the University of Sciences, Techniques and Technologies of Bamako (USTTB)

Impact of biochar on soil hydrodynamics properties, water economy and tomato (Solanum lycopersicum l.) yield in a context of climate change, in semi-arid zone, Senegal.

2026-07-21T13:41:34Z

Impact of biochar on soil hydrodynamics properties, water economy and tomato (Solanum lycopersicum l.) yield in a context of climate change, in semi-arid zone, Senegal. Diedhiou, Siméon In Senegal, the long period of the dry season, the insufficient amount of water in the rainy season, the water pollution, and the increase in population led to a decrease in freshwater resources and put it under pressure and competition among the users. Inadequate agricultural water management combined with the weak capacity of most Senegalese soils to hold water will lead to more inefficient irrigation water use. This study aims to assess the impact of biochar on tomato yield, growth, and irrigation water use efficiency (IWUE) in sandy-loam soil in West Africa-Senegal. A two growing seasons factorial experiment was conducted with a combination deficit irrigation-biochar from February 2021 to February 2023 with three irrigation levels, i.e. full irrigation (recommended-W0=40L.day-1), 75% of full irrigation (W1=30L.day-1), and 50% of full irrigation (W2=20L.day-1), and three amount of biochar, i.e. 3kg.m-2 (B2), 50%B2 (B1=1.5kg.m-2), and 0%B2 (B0=0 kg.m-2) (control). The application of the irrigation treatment and the measurement of different parameters started 10 days after transplantation. The results showed that the use of biochar over two years of experiment had improved soil bulk density, porosity, and moisture content at field capacity. The growth parameters of tomatoes evolved during the two years of the experiment, going from disparate results in season one to clear significant (P<0.01 and P<0.05) impacts in the second season. The evolution of the yield of tomatoes from growing season one to growing season two was up to 71.5%. Furthermore, our results suggest that biochar treatment, regardless of the amount of irrigated water level, presents a better IWUE than full irrigation without biochar (W0B0). The combination biochar’s lowest irrigation water level (W2B1 or W2B2) can allow water economy up to 50% of full irrigation without compromising the yield. A thesis, in the Rural Polytechnic Institute of Training and Applied Research (IPR/IFRA) in partnership with the West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL), submitted in partial fulfilment of the requirements for the Doctor of Philosophy in Climate Change and Agriculture of the University of Sciences, Techniques and Technologies of Bamako (USTTB)

Biochar and N-Fertilisation Effects on Greenhouse Gases Emissions and Productivity of Low Land Rice

2026-07-21T13:31:56Z

Biochar and N-Fertilisation Effects on Greenhouse Gases Emissions and Productivity of Low Land Rice Iboko, Maduabuchi Paul Paddy field is an important source of methane (CH4) and nitrous oxide (N2O) which causes global warming. Biochar has been reported to mitigate the emission of these gases. However, its efficacy under co-application with nitrogen (N) and zero tillage is largely unknown. We conducted a two-year study at AfricaRice researcher centre Bouake, Cote Divoire to investigate the potential of combined biochar and nitrogen fertiliser (N) application in mitigating N2O and CH4 emissions and improving low land rice yield and soil properties under no tillage. A completely randomized block design composed of 12 treatments and three replications were used. Treatments included: control (C1N2, tillage with hoe + 120 kgN/ha ), low biochar (B1, biochar at 3 t/ha ), high biochar (B2, biochar at 6 t/ha), activated biochar (BA, biochar at 3 t/ha + cow dung at 5 t/ha), medium N (N2, 120 kgN/ha), high N (N3, 180 kgN/ha), low biochar and low N (B1N1, biochar at 3 t/ha + 60 kgN/ha), low biochar and medium N (B1N2, biochar at 3 t/ha + 120 kgN/ha), low biochar and high N (B1N3, biochar at 3 t/ha + 180 kgN/ha), high biochar and low N (B2N1,biochar at 6 ton/ha + 60 kgN/ha ), high biochar and medium N (B2N2, biochar at 6 t/ha + 120 kgN/ha), high biochar and high N (B2N3, biochar at 6 t/ha + 180 kgN/ha). Findings indicated that rice straw biomass was most responsive to treatment application. C1N2 recorded highest cumulative CH4 emission (195.04 kg/ha) while lowest CH4 emission (98.15 kg/ha) was observed in BA. N application enhanced CH4 emission than biochar but biochar promoted N2O emissions. B2N2 produced highest N2O emission (4.14 kg/ha) while the lowest N2O emission (0. 48 kg/ha) occurred in B1. Activation of biochar with cow dung, BA did not trigger any major change in either CH4 or N2O emission compared to B1 but significantly decreased GWP and GHGI compared to C1N2. Relative to B2N2 and B2N3, GWP, GHGI and carbon sequestration were significantly decreased by B1. Increasing biochar increased carbon sequestration. More so, increasing N with or without biochar progressively increased rice yield whereas increasing biochar alone without N from B1 to B2 decreased rice yield. B2N3 and B2N2 both significantly promoted rice yield more than C1N2. In contrast, increasing biochar without N, from B1 to B2 increased rice harvest index similar to BA. Weak and positive correlations were found between rice morphological traits and GHG emissions as well as GHG emission and rice yield. Regardless of rates, neither the application of biochar with or without N nor the application of N with or without biochar significantly impacted soil properties. Co-application of N application with biochar decreased GHGs emissions, sequestered carbon and improved rice yield over the current farmer’s management practices. B2N3 is an adoption candidate by farmers due to its high rice yield potential and relative environmental friendliness. A thesis, in the Rural Polytechnic Institute of Training and Applied Research (IPR/IFRA) in partnership with the West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL), submitted in partial fulfilment of the requirements for the Doctor of Philosophy in Climate Change and Agriculture of the University of Sciences, Techniques and Technologies of Bamako (USTTB)