Cropping intensity is one of the most important decisions made independently by farmers in Vietnam. It is a crucial variable of various economic and process-based models. Rice is grown under irrigated triple- and double-rice cropping systems and a rainfed single-rice cropping system in the Vietnamese Mekong Delta (VMD). These rice cropping systems are adopted according to the geographical location and water infrastructure. However, little work has been done to map triple-cropping of rice using Sentinel-1 along with the effects of water infrastructure on the rice cropping intensity decision. This study is focused on monitoring rice cropping patterns in the An Giang province of the VMD from March 2017 to March 2018. The fieldwork was carried out on the dates close to the Sentinel-1A acquisition. The results of dual-polarized (VV and VH) Sentinel-1A data show a strong correlation with the spatial patterns of various rice growth stages and their association with the water infrastructure. The VH backscatter (σ°) is strongly correlated with the three rice growth stages, especially the reproductive stage when the backscatter is less affected by soil moisture and water in the rice fields. In all three cropping patterns, σ°VV and σ°VH show the highest value in the maturity stage, often appearing 10 to 12 days before the harvesting of the rice. A rice cropping pattern map was generated using the Support Vector Machine (SVM) classification of Sentinel-1A data. The overall accuracy of the classification was 80.7% with a 0.78 Kappa coefficient. Therefore, Sentinel-1A can be used to understand rice phenological changes as well as rice cropping systems using radar backscattering.
Conservation and restoration are crucial to maintaining a wide range of functions and services in wetlands, but it is difficult to find a reasonable and resource-efficient management option without sacrificing ecological values. In the present paper, we analyse the variability and dynamics of the chemical composition and energy potential of biomass from reedbeds, floodplain meadows, coastal meadows and reed canary grass cultivation in extracted peatlands. We observed that the chemical characteristics that are crucial for bioenergy production vary by biomass origin and over time. The bioenergy potential depends on biomass production and on the conversion method. The results indicate that the energy potential ranges from 122 to 190 GJ/ha per year in semi-natural floodplain meadows in the boreal zone. About 160 GJ/ha per year can be obtained from natural reedbeds but only about 120 GJ/ha per year from cultivated extracted peatlands. Using methane conversion, we can obtain only about 50%, and using ethanol conversion we can obtain less than 20% of the total energy potential of the herbaceous biomass of floodplain meadows. Although long-term studies on homo-and heterogeneous biomass production are required, we conclude that the local biomass of natural, semi-natural and artificial wetlands could contribute significantly to sustainable development.
This paper examines the effects of agricultural research expenditure and climate change on agricultural productivity growth by region in Ghana. A panel dataset is constructed for 2000-2009 from the Food and Agriculture Organization of the United Nations; the Ministry of Food and Agriculture, Ghana; and the Agriculture Science and Technology Indicators (ASTI) database of the International Food Policy Research Institute. A Malmquist index was used to compute agricultural productivity growth, including decomposition components efficiency change and technical change. The determinants of productivity growth are examined using a fixed effects regression model. The results specify that significant causal factors impact positively on Ghana’s agricultural productivity growth, include climate variability, infrastructure, and agricultural research and development expenditure. The study confirms there is a need to strengthen and develop new technological progress for sustainable agricultural production in Ghana.
Currently in many cities and rural areas of Vietnam, wastewater is discharged to the environment without any treatment, which emits considerable amount of greenhouse gas (GHG), particularly methane. In this study, four GHG emission scenarios were examined, as well as the baseline scenario, in order to verify the potential of GHG reduction from domestic wastewater with adequate treatment facilities. The ArcGIS and ArcHydro tools were employed to visualize and analyze GHG emissions resulting from discharge of untreated wastewater, in rural areas of Vu Gia Thu Bon river basin, Vietnam. By applying the current IPCC guidelines for GHG emissions, we found that a reduction of GHG emissions can be achieved through treatment of domestic wastewater in the studied area. Compared with baseline scenario, a maximum 16% of total GHG emissions can be reduced, in which 30% of households existing latrines are substituted by Japanese Johkasou technology and other 20% of domestic wastewater is treated by conventional activated sludge.
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