Grassland soil organic carbon (SOC) is sensitive to anthropogenic activities. Increased anthropogenic disturbance related to overgrazing has led to widespread alpine grassland degradation on the Tibetan Plateau. The degraded grasslands are considered to have great potential for carbon sequestration after adoption of improved management practices. Here, we calibrated and employed the Century model to investigate the effects of overgrazing and improved managements on the SOC dynamics in alpine meadows. We calibrated Century model against plant productivity at Haibei Research Station. SOC stocks for validation were obtained in 2009-2010 from degraded alpine meadows in two communes. We found that Century model can successfully capture grassland SOC changes. Overall, our simulation suggests that degraded alpine meadow SOC significantly increased with the advent of restoration managements from 2011 to 2030. Carbon sequestration rates ranged between 0.04 Mg C ha-1 yr-1 in lightly degraded winter grasslands and 2.0 Mg C ha-1 yr-1 in moderately degraded summer grasslands. Our modeling work also predicts that improve management in Tibetan degraded grasslands will contribute to an annual carbon sink of 0.022-0.059 Pg C yr-1. These results imply that restoration of degraded grasslands in Tibetan Plateau has great potential for soil carbon sequestration to mitigate greenhouse gases.
Tag: organic carbon
Pruning and green manure from Alnus acuminata improve soil health, and potato and wheat productivity in Rwanda
Alnus (Alnus acuminata Kunth) has been widely promoted under climate change mitigation and adaptation programs in the East African highlands. However, information is lacking on the impact of pruning management and green manure (GM) application on soil health and the productivity of associated crops. Using a large suit of soil quality indicators, crop growth and yield measurements, this study identified appropriate combinations of alnus pruning levels and GM application for sustainable intensification of potato (Solanum tuberosum) and wheat (Triticum aestivum) production in alley cropping with Alnus. This study compared six treatments, namely, (1) sole crops of potato or wheat (control), (2) sole crop + GM, (3) 75% pruning, (4) 75% pruning + GM, (5) 90% pruning and (6) 90% pruning + GM. In all treatments potato and wheat were grown in rotation. The best treatments were the 75% pruning + GM and 90% pruning + GM, which significantly differed from the control in soil pH, soil organic carbon (SOC), total nitrogen (TN), total phosphorus (P), exchangeable calcium (Ca) contents, the N:P and C:P stoichiometric ratios and the soil structural stability index (SSI). These treatments increased soil pH by 5–6%, SOC by 74–82%, TN by 58–68%, exchangeable Ca by 76–81%, total P by 17–21%, the N:P ratio by 40%, C:P ratio by 43–51%, SSI by 71–79%, potato tuber yields by 17–21% and wheat yields by 21–32% over the control. Therefore, it is concluded that pruning and application of alnus green manure can significantly improve soil health and crop productivity on degraded soils in the study area.
Assessing the spatial distribution of aerosols and air quality over the Ganga River basin during COVID-19 lockdown phase-1
The present study aims to analyze the variations in aerosol optical depth (AOD), black carbon (BC), organic carbon (OC), sulfate (SO4), dust, sea salt, fine mode dust and sea salt, and air quality over the Ganga River basin (GB), during the nation-wise lockdown phase-1 due to the outbreak of COVID-19. The aerosol data have been obtained from Moderate Resolution Imaging Spectroradiometer (MODIS) and Modern-Era Retrospective analysis for Research and Applications (MERRA-2) for the lockdown phase-1 (March 25 – April 15, 2020) and its corresponding average of the reference period (2001-2019). The total PM2.5 has been modeled over the GB based on the inputs from MERRA-2. The in-situ air quality index (AQI) values from cities across the GB have been obtained during pre-lockdown (February, 29 – March 20, 2020) and lockdown phase-1 period to evaluate changes. Non-parametric pairwise comparison is performed to evaluate the significant change in the pollutants including AOD, and quantile regression is used to explore the effect of meteorology on AOD and other pollutants. The results show a significant reduction (p ≤ 0.05) in AOD, BC, OC, SO4, dust, dust particulate matter (PM2.5), sea salt, sea salt PM2.5, and estimated total PM2.5 during the lockdown phase-1 with respect to the reference period. The analysis also reveals that meteorological factors do not play a vital role in the reduction of AOD during the lockdown phase-1 period. The estimated reductions for AOD, BC, OC, SO4, dust, dust PM2.5, sea salt, and sea salt PM2.5 are 33%, 21%, 24%, 20%, 18%, 17%, 64%, and 61%, respectively due to imposition of lockdown measures. As many as 28 cities in the GB have shown substantial improvement in the air quality during the lockdown phase-1 period. The reduction in the emission quantity and subsequent improvement in AQI has opened up a new discourse for combatting the persistent air quality issues for million-plus cities in particular and for the north Indian plain in general. The findings of this study thus provide insightful views to the environmentalists and policymakers for framing better emission policy to deal with the air quality issue.
Exploring biochar and Moringa oleifera seed proteins for greywater remediation on small farms
This study investigated the potential of using biochar and Moringa oleifera seed proteins for sustainable greywater treatment in rural Kenya. Greywater samples from washing clothes were collected from households in the Kenyan counties of Kwale and Siaya. Two treatment methods, batch stirring and filtration, were used to assess the effectiveness of using biochar and Moringa oleifera seed protein extract together to treat greywater at a household level. Both methods achieved a significant reduction in contaminants: colour was reduced by up to 43% in Kwale and 67% in Siaya, turbidity decreased by 91–98%, and surfactant levels were lowered by 89–93%. There were increases in total organic carbon and total dissolved solids post-treatment, but both methods effectively reduced levels of phosphates, nitrates and iron. This research highlights the potential of using locally available materials for greywater treatment and provides insights into sustainable water management nature-based solutions in the Global South.