{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:14:31Z","timestamp":1760058871199,"version":"build-2065373602"},"reference-count":34,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2025,5,7]],"date-time":"2025-05-07T00:00:00Z","timestamp":1746576000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT\u2014Portuguese Foundation for Science and Technology","award":["LA\/P\/0126\/2020","UID\/04033","UIDB\/04011\/2020","UIDB\/05183\/2020","PRT\/BD\/152094\/2021"],"award-info":[{"award-number":["LA\/P\/0126\/2020","UID\/04033","UIDB\/04011\/2020","UIDB\/05183\/2020","PRT\/BD\/152094\/2021"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Agronomy"],"abstract":"<jats:p>The main objective of energy balance analysis is to guide farmers in making informed decisions that promote the efficient management of natural resources, optimise the use of agricultural inputs, and improve the overall economic performance of their farms. In addition, it supports the adoption of sustainable agricultural practices, such as crop diversification, the use of renewable energy sources, and the recycling of agricultural by-products and residues into natural energy sources or fertilisers. This paper analyses the variation in energy efficiency between 2019 and 2022 of the main crops in Angola: maize, soybean, and rice, and the forest production of eucalyptus biomass in agroforestry farms. The research was based on the responses to interviews conducted with the managers of the farms regarding the machinery used, fuels and lubricants, labour, seeds, phytopharmaceuticals, and fertilisers. The quantities are gathered by converting data into Megajoules (MJ). The results show variations in efficiency and energy balance. In corn, efficiency fluctuated between 1.32 MJ in 2019 and 1.41 MJ in 2020, falling to 0.94 MJ in 2021 due to the COVID-19 pandemic before rising to 1.31 MJ in 2022. For soybeans, the energy balance went from a deficit of \u22128223.48 MJ in 2019 to a positive 11,974.62 MJ in 2022, indicating better use of resources. Rice stood out for its high efficiency, reaching 81,541.33 MJ in 2021, while wood production showed negative balances, evidencing the need for more effective strategies. This research concludes that understanding the energy balance of agricultural operations in Angola is essential not only to achieve greater sustainability and profitability but also to strengthen the resilience of agricultural systems against external factors such as climate change, fluctuations in input prices, and economic crises. A comprehensive understanding of the energy balance allows farmers to assess the true cost-effectiveness of their operations, identify energy inefficiencies, and implement more effective strategies to maximise productivity while minimising environmental impacts.<\/jats:p>","DOI":"10.3390\/agronomy15051144","type":"journal-article","created":{"date-parts":[[2025,5,7]],"date-time":"2025-05-07T08:20:53Z","timestamp":1746606053000},"page":"1144","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Energy Efficiency of Agroforestry Farms in Angola"],"prefix":"10.3390","volume":"15","author":[{"given":"Oloiva","family":"Sousa","sequence":"first","affiliation":[{"name":"CETRAD\u2014Centre for Transdisciplinary Studies, University of Tr\u00e1s-os-Montes and Alto Douro, Quinta dos Prados, 5000-801 Vila Real, Portugal"}]},{"given":"Ludgero","family":"Sousa","sequence":"additional","affiliation":[{"name":"Faculdade de Ci\u00eancias Sociais e Tecnologia, European University, Quinta do Bom Nome, Estr. da Correia 53, 1500-210 Lisboa, Portugal"}]},{"given":"Fernando","family":"Santos","sequence":"additional","affiliation":[{"name":"Escola de Ci\u00eancias Agr\u00e1rias e Veterin\u00e1rias, University of Tr\u00e1s-os-Montes and Alto Douro, Quinta dos Prados, 5000-801 Vila Real, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5731-767X","authenticated-orcid":false,"given":"Maria Raquel","family":"Lucas","sequence":"additional","affiliation":[{"name":"Department of Management, MED (Mediterranean Institute for Agriculture, Environment and Development) & CHANGE (Global Change and Sustainability Institute), Universidade de \u00c9vora, Largo dos Colegiais, N\u00ba 2, 7004-516 \u00c9vora, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3171-2951","authenticated-orcid":false,"given":"Jos\u00e9","family":"Aranha","sequence":"additional","affiliation":[{"name":"Centre for the Research and Technology of Agroenvironmental and Biological Sciences (CITAB), Inov4Agro, Universidade de Tr\u00e1s-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,5,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1016\/j.egyr.2014.11.001","article-title":"Analysing the energy balances of double-cropped cereals in an arid region","volume":"1","author":"Zahedi","year":"2015","journal-title":"Energy Rep."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1977","DOI":"10.1590\/S0103-84782004000600050","article-title":"Agricultural energy balances: An important tool to indicate the sustainability of agroecosystems","volume":"3","author":"Campos","year":"2004","journal-title":"Ci\u00eanc. Rural"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"279","DOI":"10.1590\/S0044-59672009000200006","article-title":"The agroforestry systems as an alternative of sustainable land use in v\u00e1rzea (floodplain) ecosystems in Amazon State","volume":"39","author":"Castro","year":"2009","journal-title":"Acta Amaz."},{"key":"ref_4","first-page":"1977","article-title":"Energy study of biofuel production from maize","volume":"40","author":"Salla","year":"2010","journal-title":"Ci\u00eanc. Rural"},{"key":"ref_5","unstructured":"Azevedo, J.C. (2012). Forests Environment and Sustainability: An Approach Centred on Ecosystem Services in the Forests of the Bragan\u00e7a District, Academy of Sciences."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"667","DOI":"10.1590\/1679-395157473","article-title":"Sustainability and sustainable development: Unravelling the overlaps and scope of their meanings","volume":"14","author":"Feil","year":"2017","journal-title":"Cad. EBAPE"},{"key":"ref_7","first-page":"35","article-title":"Analysis of the energy balance for maize production in the State of S\u00e3o Paulo","volume":"4","author":"Ulbanere","year":"1989","journal-title":"Eng. Agr\u00edc."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"205","DOI":"10.22214\/ijraset.2023.55628","article-title":"Utilisation of conventional and non-conventional energy sources","volume":"11","author":"Bharda","year":"2023","journal-title":"Int. J. Res. Appl. Sci. Eng. Technol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1133","DOI":"10.14505\/\/jemt.v11.5(45).02","article-title":"Efficiency of using biomass from energy crops for sustainable bioenergy development","volume":"11","author":"Kulyk","year":"2020","journal-title":"J. Environ. Manag. Tour."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1761","DOI":"10.1016\/j.enconman.2005.10.003","article-title":"Energy and economic analysis of sweet cherry production in Turkey: A case study","volume":"47","author":"Demircan","year":"2006","journal-title":"Energy Conv. Manag."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"819","DOI":"10.58812\/jmws.v2i09.669","article-title":"Analisis bibliometrik pemanfaatan energi terbarukan dalam proses produksi pangan","volume":"2","author":"Lasaksi","year":"2023","journal-title":"J. Multidisiplin West Sci."},{"key":"ref_12","first-page":"49","article-title":"Energy analysis of two mechanised eucalyptus harvesting systems","volume":"70","author":"Oliveira","year":"2006","journal-title":"Sci. For."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"551","DOI":"10.58812\/wsis.v1i08.180","article-title":"Quantifying the impact of renewable energy research on environmental sustainability","volume":"1","author":"Winardi","year":"2023","journal-title":"West Sci. Interdiscip. Stud."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Benedek, A., Rokicki, T., and Szeber\u00e9nyi, A. (2023). Bibliometric evaluation of energy efficiency in agriculture. Energies, 16.","DOI":"10.3390\/en16165942"},{"key":"ref_15","first-page":"267","article-title":"Circular economy and renewable energies: A bibliometric analysis of international literature","volume":"23","author":"Alves","year":"2022","journal-title":"Interactions"},{"key":"ref_16","first-page":"265","article-title":"Bioenergy crops and alternate energy","volume":"4","author":"Dipti","year":"2013","journal-title":"Int. J. Environ. Eng. Manag."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Rastegari, A., Yadav, A., and Gupta, A. (2019). Bioenergy Crops: Recent Advances and Future Outlook. Prospects Of Renewable Bioprocessing in Future Energy Systems, Springer. Chapter 12.","DOI":"10.1007\/978-3-030-14463-0"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"106740","DOI":"10.1016\/j.jece.2021.106740","article-title":"Foresight for corn-to-ethanol mills in the Southern Brazilian Amazon: Energy economic and environmental analysis","volume":"9","author":"Ziero","year":"2021","journal-title":"J. Environ. Chem. Eng."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Sevgi, E., and Figen, A.Z. (2025). Determination of Renewable Energy Growth Using Cluster Analysis and Multi-Criteria Decision-Making Methods. Appl. Sci., 15.","DOI":"10.3390\/app15031575"},{"key":"ref_20","first-page":"59","article-title":"The effect of energy consumption on agricultural added value: Panel data analysis for transition economies and EU member","volume":"8","author":"Akyol","year":"2020","journal-title":"Anemon J. Soc. Sci. Mus Alparslan Univ."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"59","DOI":"10.34101\/actaagrar\/74\/1665","article-title":"The energy balance of maize production: Alternative approaches","volume":"74","author":"Horvath","year":"2018","journal-title":"Acta Agrar. Debreceniensis"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"51","DOI":"10.31472\/ttpe.1.2021.6","article-title":"Energy and ecological analysis of the life cycle of energy use of maize crop residues","volume":"43","author":"Geletukha","year":"2021","journal-title":"Thermophys. Therm. Power Eng."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2271","DOI":"10.5433\/1679-0359.2021v42n4p2271","article-title":"Energy efficiency in maize crops in different regions of Brazil","volume":"42","author":"Guareschi","year":"2021","journal-title":"Semin. Ci\u00eanc. Agr\u00e1r."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"191","DOI":"10.14720\/aas.2014.103.2.4","article-title":"Analysis of energy and greenhouse gas balance as indexes for environmental assessment of wheat and maize farming: A case study","volume":"103","author":"Sami","year":"2014","journal-title":"Acta Agric. Slov."},{"key":"ref_25","unstructured":"Missing, D. (2020). OECD-FAO Agricultural Outlook 2020\u20132029, OECD Publishing."},{"key":"ref_26","first-page":"53","article-title":"Understanding energy efficiency using a socioeconomic framework: The case of paddy farming in Malaysia","volume":"17","author":"Baharudin","year":"2021","journal-title":"Geography Malays. J. Soc. Space"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"102873","DOI":"10.1016\/j.agsy.2020.102873","article-title":"Editorial: Impacts of COVID-19 on agricultural and food systems worldwide and on progress to the sustainable development goals","volume":"183","author":"Stephens","year":"2020","journal-title":"Agric. Syst."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"e271","DOI":"10.1002\/fes3.271","article-title":"Increasing farm size to improve energy use efficiency and sustainability in maize production","volume":"10","author":"Zhang","year":"2021","journal-title":"Food Energy Secur."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"747","DOI":"10.4155\/bfs.10.29","article-title":"Opportunities for energy efficiency and biofuel production in Australian wheat farming systems","volume":"1","author":"Farine","year":"2010","journal-title":"Biofuels"},{"key":"ref_30","unstructured":"Meyer-Aurich, A., Balafoutis, A., Daalgard, T., Visser, C.D., Go\u0142aszewski, J., Mikkola, H., and Silva, L. (2013, January 4\u20136). Energy efficiency in agriculture\u2014Opportunities, constraints and research needs. Proceedings of the First International Symposium on Agricultural Engineering\u2014ISAE, Zemun, Serbia. Available online: https:\/\/www.researchgate.net\/publication\/303766825_Energy_Efficiency_in_Agriculture_-_Opportunities_Constrains_and_Research_Needs."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Zhu, J., Zhao, Y., Xie, Q., and Zhang, Y. (2022, January 20\u201322). Study on agricultural energy efficiency measurement and rebound effect based on DEA model. Proceedings of the International Conference on Electronic Information Engineering Big Data and Computer Technology, Sanya, China.","DOI":"10.1117\/12.2635679"},{"key":"ref_32","first-page":"100","article-title":"Energy production and use in Dutch agriculture","volume":"22","author":"Dekkers","year":"1974","journal-title":"Neth. J. Agri. Sci."},{"key":"ref_33","first-page":"293","article-title":"Factors affecting energy consumption in the agricultural sector of Iran: The application of ARDL-FUZZY","volume":"9","author":"Ziaabadi","year":"2019","journal-title":"Int. J. Agric. Manag. Dev."},{"key":"ref_34","first-page":"1829","article-title":"Determination of energy use efficiency of cotton production in Turkey: A case study from Hatay Province","volume":"28","author":"Semerci","year":"2019","journal-title":"Fresenius Environ. Bull."}],"container-title":["Agronomy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4395\/15\/5\/1144\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:28:43Z","timestamp":1760030923000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4395\/15\/5\/1144"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,5,7]]},"references-count":34,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2025,5]]}},"alternative-id":["agronomy15051144"],"URL":"https:\/\/doi.org\/10.3390\/agronomy15051144","relation":{},"ISSN":["2073-4395"],"issn-type":[{"type":"electronic","value":"2073-4395"}],"subject":[],"published":{"date-parts":[[2025,5,7]]}}}