COVID-19 and climate change concerns: Matters arising.

Until the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, developing countries, especially countries in the African continent, battled with the impact of climate change on the food value-chain systems and general livelihood. In this study, we discuss climate change concerns post-COVID-19 and argue that the outbreak of the COVID-19 pandemic has exacerbated the vulnerabilities of most developing and emerging economies. This has heightened political tensions and unrest among such developing nations. We suggest enhancement and intensification of efficient and effective locally engineered adaptation strategies in the post-COVID-19 era for countries that have been susceptible to the impact of climate change and other recent shocks.

Analyses of crop water use and environmental performance of small private irrigation along the white Volta basin of Northern Ghana.

Small private irrigation (SPI) is a farmer-initiated irrigation which has the potential to increase the contribution of the overall irrigation sector to global food security. However, there is no much information about these systems for effective policies for regulation. This study compared the resource use productivities and environmental impacts of SPI systems to those of a government-led irrigation scheme (GIS) in Northern Ghana. The results showed that land productivity was higher in the SPI than in the GIS. Productivity per unit cultivated area was 2571.00 US$/ha under SPI while that of the GIS was 676.00 US$/ha. Output per unit command area was also two times higher in the SPI than in the GIS; that is 2571.00 US$/ha and 1113.00 US$/ha for SPI and GIS respectively. For water productivity, output per unit irrigation supply was 0.33 US$/m3 and 0.08US$/m3 for SPI and GIS respectively while output per unit water consumed by ET was 0.60 US$/m3 for SPI and 0.06 US$/m3 for the GIS. The results implied that the SPI schemes performed better in land and water productivities compared with the GIS which is attributed to higher yields and the selection of high valued crops by farmers under SPI. However, both irrigation system types at the time of this study did not cause significant deterioration to the water bodies and surrounding environment as the biochemical oxygen demand (BOD) values of nearby water bodies were less than 3.0-5.0 mg/l, which is considered as acceptable levels for drinking water by World Health Organisation (WHO) while salinity levels were also within acceptable limits (<750 µS/cm). With appropriate policies to regulate and provide support systems to the SPI, these systems may increase the overall agricultural productivity and improve job creation for the teeming unemployed youth and women in the savannah agroecological zone of Ghana.

Impact of soil amendments on nitrous oxide emissions and the associated denitrifying communities in a semi-arid environment.

Denitrifying bacteria produce and utilize nitrous oxide (N2O), a potent greenhouse gas. However, there is little information on how organic fertilization treatments affect the denitrifying communities and N2O emissions in the semi-arid Loess Plateau. Here, we evaluated how the denitrifying communities are responsible for potential denitrification activity (PDA) and N2O emissions. A field experiment was conducted with five fertilization treatments, including no fertilization (CK), mineral fertilizer (MF), mineral fertilizer plus commercial organic fertilizer (MOF), commercial organic fertilizer (OFP), and maize straw (MSP). Our result showed that soil pH, soil organic carbon (SOC), and dissolved organic nitrogen (DON) were significantly increased under MSP treatment compared to MF treatment, while nitrate nitrogen (NO3 --N) followed the opposite trend. Organic fertilization treatments (MOF, OFP, and MSP treatments) significantly increased the abundance and diversity of nirS- and nosZ-harboring denitrifiers, and modified the community structure compared to CK treatment. The identified potential keystone taxa within the denitrifying bacterial networks belonged to the distinct genera. Denitrification potentials were significantly positively correlated with the abundance of nirS-harboring denitrifiers, rather than that of nirK- and nosZ-harboring denitrifiers. Random forest modeling and structural equation modeling consistently determined that the abundance, community composition, and network module I of nirS-harboring denitrifiers may contribute significantly to PDA and N2O emissions. Collectively, our findings highlight the ecological importance of the denitrifying communities in mediating denitrification potentials and the stimulatory impact of organic fertilization treatments on nitrogen dynamics in the semi-arid Loess Plateau.

Influence of conservation tillage on Greenhouse gas fluxes and crop productivity in spring-wheat agroecosystems on the Loess Plateau of China.

The effects of climate change such as dry spells, floods and erosion heavily impact agriculture especially smallholder systems on the Northwestern Loess Plateau of China. Nonetheless agriculture also contributes to global warming through the emission of greenhouse gases such as CO2, CH4 and N2O. Yet this complex conundrum can be alleviated and mitigated through sound soil and water management practices. Despite considerable literature on Conservation Agriculture (CA) as a strategy to improve the resilience and mitigation capacity of agroecosystems, there is still paucity of information on the impacts of CA on crop production and environmental quality on the Plateau. In order to fill this gap this study examined the effects of no-till and straw mulch on crop productivity and greenhouse gas fluxes in agroecosystems on the Plateau where farmers' common practice of conventional tillage (CT) was tested against three CA practices: conventional tillage with straw mulch (CTS), no-till (NT) and no-till with straw mulch (NTS). The results indicated that all three CA practices (CTS, NT and NTS) markedly increased soil water content (SWC), soil organic carbon (SOC) and soil total nitrogen (STN) but reduced soil temperature (ST). Average grain yields were 854.46 ± 76.51, 699.30 ± 133.52 and 908.18±38.64 kg ha-1 respectively under CTS, NT and NTS indicating an increase by approximately 33%, 9% and 41% respectively compared with CT (644.61 ± 76.98 kg ha-1). There were significant (p < 0.05) reductions of Net CO2 emissions under NT (7.37 ± 0.89 tCO2e ha-1y-1) and NTS (6.65 ± 0.73 tCO2e ha-1y-1) compared with CTS (10.65 ± 0.18 tCO2e ha-1y-1) and CT (11.14 ± 0.58 tCO2e ha-1y-1). All the treatments served as sinks of CH4but NTS had the highest absorption capacity (-0.27 ± 0.024 tCO2e ha-1y-1) and increased absorption significantly (p < 0.05) compared with CT (-0.21 ± 0.017 tCO2e ha-1y-1); however, CA did not reduce emissions of N2O. These had an influence on Global warming potential (GWP) as NT and NTS resulted in significant reduction in net GWP. Grain yield was significantly correlated positively with SOC and STN (p < 0.05); ecosystem respiration was also significantly correlated with SWC and ST while CH4 flux was highly correlated with ST (p < 0.001). Crop yield and GHG responses to CA were controlled by soil hydrothermal and nutrient changes, thus improving these conditions through adoption of sustainable soil moisture improvement practices such as no-till, straw mulch, green manuring, contour ploughing and terracing can improve crop resilience to climate change and reduce GHG emissions in arid and semi-arid regions.

Response of soil organic carbon to vegetation degradation along a moisture gradient in a wet meadow on the Qinghai-Tibet Plateau.

The study was conducted during the growing seasons of 2013, 2014, and 2015 in the wet meadows on the eastern Qinghai-Tibet plateau (QTP) in the Gansu Gahai Wetland Nature Reserve to determine the dynamics of soil organic carbon (SOC) as affected by vegetation degradation along a moisture gradient and to assess its relationship with other soil properties and biomass yield. Hence, we measured SOC at depths of 0-10, 10-20, and 20-40 cm under the influence of four categories of vegetation degradation (healthy vegetation [HV], slightly degraded [SD], moderately degraded [MD], and heavily degraded [HD]). Our results showed that SOC decreased with increased degree of vegetation degradation. Average SOC content ranged between 36.18 ± 4.06 g/kg in HD and 69.86 ± 21.78 g/kg in HV. Compared with HV, SOC content reduced by 30.49%, 42.22%, and 48.22% in SD, MD, and HD, respectively. SOC significantly correlated positively with soil water content, aboveground biomass, and belowground biomass, but significantly correlated negatively with soil temperature and bulk density (p < 0.05). Highly Significant positive correlations were also found between SOC and total nitrogen (p = 0.0036), total phosphorus (p = 0.0006) and total potassium (p < 0.0001). Our study suggests that severe vegetation and moisture loss led to approximately 50% loss in SOC content in the wet meadows, implying that under climate warming, vegetation and soil moisture loss will dramatically destabilize carbon sink capacities of wetlands. We therefore suggest wetland hydrological management, restoration of vegetation, plant species protection, regulation of grazing activities, and other anthropogenic activities to stabilize carbon sink capacities of wetlands.