Sustainable Resources Management
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- ItemAfrican Markets and the Utu-Ubuntu Business Model: A persepctive on economic informality in Nairobi.(African Minds, 2019) Kinyanjui, Mary Njeri
- ItemLosses of phosphorus, potassium and nitrogen from horse manure left on the ground(Taylor & Francis Group - Informa UK Limited, 2022-09-19) Aronsson, Helena; Nyström, Sofia; Malmer, Elsa; Kumblad, Linda; Winqvist, CamillaIn this five-month Swedish field study, we examined losses of nutrients from horse manure over time, in order to examine how regularly manure should be cleared from paddocks in order to minimise the risk of nutrient leaching. Small heaps of manure (400 g) were placed in open cylinders outdoors and samples (five replicates) were taken on 12 occasions from December 2020 to May 2021. The samples were analysed for weight, dry matter content and concentrations of total nitrogen (N), ammonium N, total phosphorus (P), water-extractable P (WEP), potassium (K) and carbon (C). There was a fast decline in P and K concentrations and a strong correlation between accumulated precipitation and losses from the manure into the soil. The mean reduction in total-P was 11 mg P kg−1 manure dry weight per mm accumulated precipitation. Manure N was retained in the manure over the five-month period. In conclusion, this study demonstrated high mobility of P and K, indicating a need for strategies for rapid removal of manure from paddocks. Daily removal of manure from paddocks used year-round would, approximately, save 1.7 kg P and 5.5 kg K per horse per year, which could be recycled to replace non-renewable mineral fertilisers.
- ItemGrowth, yield and fruit quality of tomato Solanum lycopersicum L grown in sewage-based compost in a semi-hydroponic cultivation system(Taylor & Francis Group - Informa UK Limited, 2022-09-27) Aurdal, Siv M.; Foereid, Bente; Trine, Sogn; Børresen, Trond; Hvoslef-Eide, Trine; Remberg, Siv FagertunPurpose: Due to environmental concerns, there is a demand to reduce the use of peat as a growing medium for horticultural crops. Simultaneously, there is an interest to recycle organic waste materials in the form of compost. This study aimed to document effects on growth, yield, and fruit quality of tomato plants when cultivated in a sewage digestate-based compost in a subirrigation container system. Materials and methods: The compost used in this experiment consisted of 30% hygienised sewage digestate from biogas extraction and 70% garden waste. The treatments were 100% compost, a peat mix and mixtures of the two in 25/75, 50/50 and 75/25 ratios. Results and conclusion: Considering the contrast in chemical and physical properties of the treatments, variations in growth, yield and quality were expected. The plants differed in leaf area and number of leaves, but there were no differences in yield or quality of the tomato fruits. It is assumed that this is in great part due to the remediating effects of subirrigation with an ideal nutrient solution, and the use of pre-established plants. Further research should focus on benefits of this cultivation system for use in sustainable horticulture in combination with recycled organic waste.
- ItemProper management of irrigation and nitrogen-application increases crop N-uptake efficiency and reduces nitrate leaching(Taylor & Francis Group - Informa UK Limited, 2022-09-28) ten Damme, Loraine; Jing, Shuxuan; Montcalm, Ashley Marie; Jepson, Maisie; Andersen, Mathias Neumann; Hansen, Elly MøllerIrrigation is, on one hand, expected to increase the risk of nitrate leaching through increased rates of percolation, but, on the other hand, enhances plant nutrient uptake and growth, thereby limiting the risk of leaching. To investigate this dichotomy, we analysed the effects of irrigation at three nitrogen (N)-application rates in spring barley (Hordeum distichum L., two experiments with 50, 100, and 150 kg N ha−1) and winter oilseed rape (Brassica napus L., one experiment with 50, 150, and 250 kg N ha−1) on a coarse sandy soil in Denmark in a humid climate, which facilitates nitrate leaching. Analyses comprised grain/seed dry matter yield, N-uptake, nitrogen use efficiency (partial nitrogen budget, PNB, and partial-factor productivity, PFP) and nitrate leaching. For both crops, increasing N-application without consideration of the crops’ drought stress responses lead to a relatively lower N-uptake in grain, lower yield, lower PNB and PFP and higher nitrate leaching, although responses were not proportionally to increasing N-application. The effect of irrigation at the lowest N-rates was limited. The non-irrigated treatments with the highest N-rates had a grain/seed yield of 3.2, 2.3 and 0.7 t ha−1 and nitrate leaching rates of 64, 72 and 127 kg N ha−1 compared to a grain/seed yield of 5.3, 5.0 and 2.6 kg N ha−1 and nitrate leaching rates of 61, 42 and 85 kg N ha−1 (for spring barley, spring barley and winter oilseed rape, respectively). These results show that synchronised management of both irrigation and N-application are essential for reducing the risk of nitrate leaching and to promote efficient crop N-uptake in periods of droughts.
- ItemGeospatial assessment of land use and land cover dynamics in the mid-zone of Ghana(Sciendo (De Gruyter), 2022-12-14) Koranteng, Addo; Adu-Poku, Isaac; Donkor, Emmanuel; Zawiła-Niedźwiecki, TomaszLand use and land cover (LULC) terrain in Ghana has undergone profound changes over the past years emanating mainly from anthropogenic activities, which have impacted countrywide and sub-regional environment. This study is a comprehensive analysis via integrated approach of geospatial procedures such as Remote Sensing (RS) and Geographic Information System (GIS) of past, present and future LULC from satellite imagery covering Ghana’s Ashanti regional capital (Kumasi) and surrounding districts. Multi-temporal satellite imagery data sets of four different years, 1990 (Landsat TM), 2000 (Landsat ETM+), 2010 (Alos and Disaster Monitoring Constellation-DMC) and 2020 (SENTINEL), spanning over a 30-year period were mapped. Five major LULC categories – Closed Forest, Open Forest, Agriculture, Built-up and Water – were delineated premised on the prevailing geographical settings, field study and remote sensing data. Markov Cellular Automata modelling was applied to predict the probable LULC change consequence for the next 20 years (2040). The study revealed that both Open Forest and Agriculture class categories decreased 51.98 to 38.82 and 27.48 to 20.11, respectively. Meanwhile, Built-up class increased from 4.8% to 24.8% (over 500% increment from 1990 to 2020). Rapid urbanization caused the depletion of forest cover and conversion of farmlands into human settlements. The 2040 forecast map showed an upward increment in the Built-up area up to 35.2% at the expense of other LULC class categories. This trend from the past to the forecasted future would demand that judicious LULC resolutions have to be made to keep Ghana’s forest cover, provide arable land for farming activities and alleviate the effects of climate change.
- ItemOceanic climate changes threaten the sustainability of Asia’s water tower(Springer Nature, 2023-03-01) Zhang, Qiang; Shen, Zexi; Pokhel, Yadu; Farinotti, Daniel; Singh, Vijay P.; Xu, Chong-Yu; Wu, Wenhuan; Wang, GangWater resources sustainability in High Mountain Asia (HMA) surrounding the Tibetan Plateau (TP)—known as Asia’s water tower—has triggered widespread concerns because HMA protects millions of people against water stress. However, the mechanisms behind the heterogeneous trends observed in terrestrial water storage (TWS) over the TP remain poorly understood. Here we use a Lagrangian particle dispersion model and satellite observations to attribute about 1 Gt of monthly TWS decline in the southern TP during 2003–2016 to westerlies-carried deficit in precipitation minus evaporation (PME) from the southeast North Atlantic. We further show that HMA blocks the propagation of PME deficit into the central TP, causing a monthly TWS increase by about 0.5 Gt. Furthermore, warming-induced snow and glacial melt as well as drying-induced TWS depletion in HMA weaken the blocking of HMA’s mountains, causing persistent northward expansion of the TP’s TWS deficit since 2009. Future projections under two emissions scenarios verified by satellite observations during 2020–2021 indicate that, by the end of the twenty-first century, up to 84% (for scenario SSP245) and 97% (for scenario SSP585) of the TP could be afflicted by TWS deficits. Our findings indicate a trajectory towards unsustainable water systems in HMA that could exacerbate downstream water stress.
- ItemTropical deforestation causes large reductions in observed precipitation(Springer Nature, 2023-03-01) Smith, C.; Baker, J. C. A.; Spracklen, D. V.Tropical forests play a critical role in the hydrological cycle and can influence local and regional precipitation. Previous work has assessed the impacts of tropical deforestation on precipitation, but these efforts have been largely limited to case studies. A wider analysis of interactions between deforestation and precipitation—and especially how any such interactions might vary across spatial scales—is lacking. Here we show reduced precipitation over deforested regions across the tropics. Our results arise from a pan-tropical assessment of the impacts of 2003–2017 forest loss on precipitation using satellite, station-based and reanalysis datasets. The effect of deforestation on precipitation increased at larger scales, with satellite datasets showing that forest loss caused robust reductions in precipitation at scales greater than 50 km. The greatest declines in precipitation occurred at 200 km, the largest scale we explored, for which 1 percentage point of forest loss reduced precipitation by 0.25 ± 0.1 mm per month. Reanalysis and station-based products disagree on the direction of precipitation responses to forest loss, which we attribute to sparse in situ tropical measurements. We estimate that future deforestation in the Congo will reduce local precipitation by 8–10% in 2100. Our findings provide a compelling argument for tropical forest conservation to support regional climate resilience.
- ItemCosmopolitan conservation: the multi-scalar contributions of urban green infrastructure to biodiversity protection(Springer Nature, 2023-05-04) Grabowski, Zbigniew; Fairbairn, Andrew J.; Teixeira, Leonardo H.; Fakirova, Elizaveta; Adeleke, Emannuel; Meyer, Sebastian T.; Traidl-Hoffmann; Schloter, Michael; Helmreich, BrigetteUrbanization is a leading cause of biodiversity loss globally. Expanding cities alter regional ecological processes by consuming habitat and modifying biogeochemical and energetic flows. Densifying cities often lose valuable intra-urban green spaces. Despite these negative impacts, novel urban ecosystems can harbor high biodiversity and provide vital ecosystem services for urban residents. Recognizing the benefits of urban ecosystems, cities across the globe are increasingly planning for urban green infrastructure (UGI). UGI as a planning concept can transform how cities integrate biodiversity into urbanized landscapes at multiple scales and contribute to conservation goals. Full operationalization of UGI concepts can also reduce urban energy and resource demands via substituting polluting technologies by UGI, further contributing to the global conservation agenda. Realizing the potential contributions of UGI to local, regional, and global conservation goals requires addressing four inter-dependent challenges: (1) expanding social-ecological-systems thinking to include connections between complex social, ecological, and technological systems (SETS), (2) explicitly addressing multi-level governance challenges, (3) adapting SETS approaches to understand the contextual and biocultural factors shaping relationships between UGI and other causal processes in cities that shape biodiversity, and (4) operationalizing UGI systems through robust modeling and design approaches. By transforming UGI policy and research through SETS approaches to explicitly integrate biodiversity we can support global conservation challenges while improving human wellbeing in cities and beyond.