Your search found 6 records
1 Jewitt, G.; Kunz, R.. 2011. The impact of biofuel feedstock production on water resources: a developing country perspective. Biofuels, Bioproducts and Biorefining, 5(4):387-398.
Bioenergy ; Biofuels ; Feedstocks ; Water resources ; Water management ; Developing countries ; Environmental flows ; Water use ; Water users ; Land use / Africa South of Sahara
(Location: IWMI HQ Call no: e-copy only Record No: H044736)
(0.57 MB)
Worldwide, the demand for energy has grown rapidly over the past decade, resulting in oil prices peaking during 2008 and again in 2011. Utilizing the potential for the production of fuels from alternative sources has been a priority for many countries, particularly the developed countries of Europe and America. The production of ethanol and diesel from vegetable biomass and oils, (i.e. biofuels) has been promoted as an environmentally friendly alternative to oil-based fuels. However, many have warned against the rush to plant large areas of land for bioenergy production, warning against, inter alia, potential consequences for loss of food production, questions about the sustainability of many initiatives and, very importantly, queries about the water use of bioenergy production, from the crop growth to the fi nal synthesis of the liquid fuel and the inputs required. Many analyses of biofuel feedstock production potential are undertaken at macro levels, based on average conditions. However, the reality is that in many developing countries, particularly those of Africa, consideration of biofuel production and its sustainability requires specifi c consideration of the high natural variability of climatic and other factors governing its production and impact. In this paper, perspectives on the water resources aspects of large-scale biofuel feedstock production in sub-Saharan Africa are provided and the approach taken by South Africa in this regard is described.
2 Masanganise, J.; Kunz, R.; Clulow, A. D.; Mabhaudhi, T.; Savage, M. J. 2022. Evapotranspiration estimates of soybean using surface renewal: comparison with crop coefficient approach. Physics and Chemistry of the Earth, 128:103244. (Online first) [doi: https://doi.org/10.1016/j.pce.2022.103244]
Evapotranspiration ; Estimation ; Soybeans ; Energy balance ; Sensible heat ; Latent heat ; Micrometeorology ; Crops ; Plant developmental stages ; Soil water content ; Weather data ; Air temperature / South Africa / KwaZulu-Natal
(Location: IWMI HQ Call no: e-copy only Record No: H051442)
(0.88 MB)
Evapotranspiration (ET) is widely considered the main consumptive water use in agricultural production and its accurate determination enables crop producers to make informed decisions. Field experiments were conducted in KwaZulu-Natal, South Africa to estimate soybean ET from sensible and latent heat flux obtained using the surface renewal (SR) method. Two versions of the SR method (SR2) were used. One version combines SR analysis with Monin-Obukhov similarity theory (MOST), hereinafter referred to as SRMOST. The other is a combination of SR analysis and dissipation theory (DT) referred to as SRDT. The ET estimated using SRMOST and SRDT (ETSRMOST and ETSRDT respectively) were compared to the ET obtained using the standard crop coefficient (Kc) approach (ETKc). During flowering, pod formation and seed filling, both SRMOST and SRDT methods slightly overestimated ET obtained using Kc approach with an average normalised root mean square error (NRMSE) of 23.4% and an average normalised mean absolute error (NMAE) of 10.1% for SRMOST and 21.7 and 9.4% for SRDT respectively. During senescence and at maturity, SRMOST and SRDT slightly underestimated ET compared to Kc approach. The average statistical measures for SRMOST were NRMSE = 21.0% and NMAE = 9.2%. Correspondingly, the statistics for SRDT were 17.5 and 7.1% respectively. Both SR2 methods estimated the minimum ET more accurately compared to the maximum. The SRDT method was more in agreement with Kc approach. Surface renewal is robust, less expensive than other micrometeorological techniques and a reliable method for deriving evapotranspiration of soybean when crop coefficients are problematic.
3 Nhamo, L.; Paterson, G.; van der Walt, M.; Moeletsi, M.; Modi, A.; Kunz, R.; Chimonyo, V.; Masupha, T.; Mpandeli, S.; Liphadzi, S.; Molwantwa, J.; Mabhaudhi, Tafadzwanashe. 2022. Optimal production areas of underutilized indigenous crops and their role under climate change: focus on Bambara groundnut. Frontiers in Sustainable Food Systems, 6:990213. [doi: https://doi.org/10.3389/fsufs.2022.990213]
Crop production ; Bambara groundnut ; Vigna subterranea ; Underutilized species ; Indigenous organisms ; Climate change adaptation ; Strategies ; Resilience ; Dryland farming ; Land suitability ; Food security ; Water security ; Rain ; Geographical information systems / South Africa / Limpopo
(Location: IWMI HQ Call no: e-copy only Record No: H051486)
https://www.frontiersin.org/articles/10.3389/fsufs.2022.990213/pdf
https://vlibrary.iwmi.org/pdf/H051486.pdf
https://vlibrary.iwmi.org/pdf/H051486.pdf
(2.66 MB) (2.66 MB)
Food demand in Africa continues to outstrip local supply, and the continent currently spends over US$35 billion annually on food imports to supplement local deficits. With the advances in agronomy and breeding, commercial crops like maize (Zea mays) and soybean (Glycine max) in the region are under threat from climate change, decreasing rainfall and degraded lands. Unlike commercial crops that are generally adapted from other regions, underutilized indigenous crops are uniquely suited to local environments and are more resilient to climatic variations and tolerant to local pests and diseases. This study, done in Limpopo Province, South Africa, identifies optimal areas for cultivating Bambara groundnuts (Vigna subterannea), an indigenous crop suitable for arid and semi-arid regions. The aim is to promote the production of underutilized indigenous crops at a large scale with fewer resources, while still meeting local demand and reducing the food import budget. Suitability maps are delineated using a multicriteria decision method in a Geographic Information System (GIS). The procedure is important for diversifying farming systems, making them more resilient (to biotic and abiotic stresses and climate change) and more successful at enhancing water, food and nutritional security. With the province’s limited water and land resources for agriculture expansion, promoting indigenous underutilized crops is a pathway to reduce water allocated to agriculture, thereby enhancing drought resilience and ensuring water, food and nutritional security. Large tracts of degraded agricultural land deemed unsuitable for adapted crops, and which may require costly land reclamation practices, can be used to cultivate underutilized crops that are adapted to extreme local conditions.
4 Mugiyo, H.; Chimonyo, V. G. P.; Kunz, R.; Sibanda, M.; Nhamo, L.; Masemola, C. R.; Modi, A. T.; Mabhaudhi, Tafadzwanashe. 2022. Mapping the spatial distribution of underutilised crop species under climate change using the MaxEnt model: a case of KwaZulu-Natal, South Africa. Climate Services, 28:100330. [doi: https://doi.org/10.1016/j.cliser.2022.100330]
Crop production ; Underutilized species ; Spatial distribution ; Climate change adaptation ; Food security ; Nutrition security ; Sorghum ; Cowpeas ; Amaranthus ; Taro ; Machine learning ; Models ; Forecasting / South Africa / KwaZulu-Natal
(Location: IWMI HQ Call no: e-copy only Record No: H051487)
https://www.sciencedirect.com/science/article/pii/S2405880722000486/pdfft?md5=6c4991c59d70a740431da7b2b337a330&pid=1-s2.0-S2405880722000486-main.pdf
https://vlibrary.iwmi.org/pdf/H051487.pdf
https://vlibrary.iwmi.org/pdf/H051487.pdf
(9.38 MB) (9.38 MB)
Knowing the spatial and temporal suitability of neglected and underutilised crop species (NUS) is important for fitting them into marginal production areas and cropping systems under climate change. The current study used climate change scenarios to map the future distribution of selected NUS, namely, sorghum (Sorghum bicolor), cowpea (Vigna unguiculata), amaranth (Amaranthus) and taro (Colocasia esculenta) in the KwaZulu-Natal (KZN) province, South Africa. The future distribution of NUS was simulated using a maximum entropy (MaxEnt) model using regional circulation models (RCMs) from the CORDEX archive, each driven by a different global circulation model (GCM), for the years 2030 to 2070. The study showed an increase of 0.1–11.8% under highly suitable (S1), moderately suitable (S2), and marginally suitable (S3) for sorghum, cowpea, and amaranth growing areas from 2030 to 2070 across all RCPs. In contrast, the total highly suitable area for taro production is projected to decrease by 0.3–9.78% across all RCPs. The jack-knife tests of the MaxEnt model performed efficiently, with areas under the curve being more significant than 0.8. The study identified annual precipitation, length of the growing period, and minimum and maximum temperature as variables contributing significantly to model predictions. The developed maps indicate possible changes in the future suitability of NUS within the KZN province. Understanding the future distribution of NUS is useful for developing transformative climate change adaptation strategies that consider future crop distribution. It is recommended to develop regionally differentiated climate-smart agriculture production guidelines matched to spatial and temporal variability in crop suitability.
5 Chimonyo, V. G. P.; Chibarabada, T. P.; Choruma, D. J.; Kunz, R.; Walker, S.; Massawe, F.; Modi, A. T.; Mabhaudhi, Tafadzwanashe. 2022. Modelling neglected and underutilised crops: a systematic review of progress, challenges, and opportunities. Sustainability, 14(21):13931. (Special issue: Interdisciplinary Approaches to Mainstreaming Underutilized Crops) [doi: https://doi.org/10.3390/su142113931]
(Location: IWMI HQ Call no: e-copy only Record No: H051496)
https://www.mdpi.com/2071-1050/14/21/13931/pdf?version=1666790014
https://vlibrary.iwmi.org/pdf/H051496.pdf
https://vlibrary.iwmi.org/pdf/H051496.pdf
(0.91 MB) (930 KB)
Developing and promoting neglected and underutilised crops (NUS) is essential to building resilience and strengthening food systems. However, a lack of robust, reliable, and scalable evidence impedes the mainstreaming of NUS into policies and strategies to improve food and nutrition security. Well-calibrated and validated crop models can be useful in closing the gap by generating evidence at several spatiotemporal scales needed to inform policy and practice. We, therefore, assessed progress, opportunities, and challenges for modelling NUS using a systematic review. While several models have been calibrated for a range of NUS, few models have been applied to evaluate the growth, yield, and resource use efficiencies of NUS. The low progress in modelling NUS is due, in part, to the vast diversity found within NUS that available models cannot adequately capture. A general lack of research compounds this focus on modelling NUS, which is made even more difficult by a deficiency of robust and accurate ecophysiological data needed to parameterise crop models. Furthermore, opportunities exist for advancing crop model databases and knowledge by tapping into big data and machine learning.
6 Gokool, S.; Mahomed, M.; Kunz, R.; Clulow, A.; Sibanda, M.; Naiken, V.; Chetty, K.; Mabhaudhi, Tafadzwanashe. 2023. Crop monitoring in smallholder farms using unmanned aerial vehicles to facilitate precision agriculture practices: a scoping review and bibliometric analysis. Sustainability, 15(4):3557. (Special issue: Advanced Technologies, Techniques and Process for the Sustainable Precision Agriculture) [doi: https://doi.org/10.3390/su15043557]
Precision agriculture ; Crop monitoring ; Smallholders ; Farming systems ; Unmanned aerial vehicles ; Bibliometric analysis ; Food security ; Machine learning ; Remote sensing ; Technology
(Location: IWMI HQ Call no: e-copy only Record No: H051762)
https://www.mdpi.com/2071-1050/15/4/3557/pdf?version=1676858967
https://vlibrary.iwmi.org/pdf/H051762.pdf
https://vlibrary.iwmi.org/pdf/H051762.pdf
(1.95 MB) (1.95 MB)
In this study, we conducted a scoping review and bibliometric analysis to evaluate the state-of-the-art regarding actual applications of unmanned aerial vehicle (UAV) technologies to guide precision agriculture (PA) practices within smallholder farms. UAVs have emerged as one of the most promising tools to monitor crops and guide PA practices to improve agricultural productivity and promote the sustainable and optimal use of critical resources. However, there is a need to understand how and for what purposes these technologies are being applied within smallholder farms. Using Biblioshiny and VOSviewer, 23 peer-reviewed articles from Scopus and Web of Science were analyzed to acquire a greater perspective on this emerging topical research focus area. The results of these investigations revealed that UAVs have largely been used for monitoring crop growth and development, guiding fertilizer management, and crop mapping but also have the potential to facilitate other PA practices. Several factors may moderate the potential of these technologies. However, due to continuous technological advancements and reductions in ownership and operational costs, there remains much cause for optimism regarding future applications of UAVs and associated technologies to inform policy, planning, and operational decision-making.
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