Boitshwarelo Lorato Masocha

This study investigates methane, a potent greenhouse gas linked to global warming, using high-resolution satellite data from the Sentinel-5P TROPOMI between 2020 and 2023. The research analyzed trends, seasonal changes, and emission hotspots in two different regions of Botswana: Central and Ngamiland. These areas have different methane sources, including human activities and natural processes. The results indicate significantly varying mean CH₄ concentrations ranging from 1750 to 1900 ppb. The Central region has greater variability in concentrations with values between 1832.93 and 1888.86 ppb, compared to Ngamiland which has CH₄ distribution ranging from 1837.92 to 1872.99 ppb. Increased summer CH₄ levels are attributed by higher temperatures and wetter conditions that stimulate methanogenesis. In winter, levels lower due to cooler temperatures and dry conditions that reduce biological activity. Time-series analysis indicated an upward trend in both regions, suggesting an increase in emissions. The Mann–Kendall tests these significant upward trends in both areas. In late 2021, both regions showed positive anomalies, indicating potential methane risks in subsequent months/years. The ongoing rise in methane concentrations poses serious environmental and health threats to Botswana without effective action. Thus, this study supports focused mitigation strategies and seasonal management that aligns with Sustainable Development Goal 13 (Climate Action). This approach provides policymakers and environmentalists with valuable insights to combat climate change and support healthier, more sustainable communities.

Low agricultural output and a decline in plant-available nutrient content in soil pose significant challenges to developing countries. To test the hypothesis that poultry litter and its biochar improve soil quality, nutrient status, and plant growth, a greenhouse pot experiment with sandy-loam soil was conducted. Selected application rates of poultry litter (0, 15, 30, 60, and 120 g/kg) and its biochar pyrolyzed at 350 °C and 600 °C were used. With the addition of organic amendments, Jatropha plant height, leaf number, and stem diameter improved significantly, as did soil fertility indicators (pH, organic matter content, cation exchange capacity, and plant-available nutrients). When compared to the control, increased application rates ranging from 60 g/kg to 120 g/kg significantly improved soil properties and plant growth. PL (Poultry litter)- and BC350 (Biochar produced at 350 °C)-treated soil outperformed other organic amendments in terms of soil quality, nutrient status, and plant growth. Soil pH, CEC, and OM were found to be positively correlated with available plant nutrients, with PL-treated soils having higher levels of plant available nutrients. Because the properties of the feedstocks complement each other, combined organic amendments improved studied parameters, particularly PLBC600 (Poultry litter mixed with biochar produced at 600 °C) compared to BC600 (Biochar produced at 600 °C). Increased application rates of pure and combined feedstock effectively increased soil fertility and Jatropha growth; however, lower temperature biochar is recommended for use as a soil organic amendment.

Poultry litter and biochar contribute to improved plant growth due to their high nutrient content. However, to the best of our knowledge, how incorporating poultry litter and its biochar in soil affects photosynthesis-related parameters of Jatropha curcas L. has not been reported. Therefore, a greenhouse pot experiment was conducted using a complete randomised design with three replicates per treatment to determine the effects of poultry litter, biochar pyrolysed at 350 °C and 750 °C at different application rates (0, 0.5, 1, 2, 3 gkg-1) on Jatropha curcas L. photosynthesis parameters. The control plants recorded the lowest values of photosynthesis-related parameters compared to the treated plants except for water use efficiency. The study observed a significant (P < 0.05) increase in leaf surface area (1807 m2, PL), dark-adapted Fv/Fm ratio, carbon dioxide uptake, and transpiration rate for PL and BC350 with increased application rates, compared to BC750 treatments. BC350 treated plants exhibited higher values (0.79) of Light-adapted Fv’/Fm’. The quantum yield of PSII electron transport displayed an increase with an application rate of 3 gkg-1in PL (0.75) treated soils. Comparing organic amendments used, BC350 exhibited a significantly higher value of carbon dioxide uptake rate (2.67 μmol m-2 s-1) and transpiration rate (2.20 mmol m-2 s-1); however, WUE increased at an application rate of 3 gkg-1 in BC750 (3.8 µmol (CO2) mol-1(H2O)) treated plants. The study results indicate that poultry litter and biochar produced at a lower temperature significantly improved photosynthesis parameters than biochar produced at a higher temperature.