Soybean is one of the most important cash crops in the world. It is among the few plant-based foods that provide high-quality proteins, with nine essential amino acids ^[1]. This unique quality makes it an ideal candidate as both a direct and indirect protein source for humans and farm animals. Today, more than 85% of soybean harvest is extracted for oil and crushed into meal to make animal feed, oil and biodiesel; the rest is used for human consumption and industrial ingredients [2,3,4]^[2][3][4]. The production and movement of this crop is closely associated with a country’s economy, food security and social equality development [5,6,7]^[5][6][7]. Apart from the traditional soybean-producing countries/regions in America and Asia, Africa is also predicted to be next major soybean-producing continent ^[8]. Furthermore, soybean is also gaining importance in sustainable agriculture due to its nitrogen fixation ability. Soybean has been demonstrated to be an effective nitrogen supplier in cropping systems that can significantly reduce demand on synthetic fertilizers, nitrogen leaching and air pollution [9,10]^[9][10]. Shifting to a soybean-oriented plant-based diet could also significantly reduce PM_2.5 and consequential premature death ^[11].

Soybean is grown in many different parts of the world. Its production has expanded fast, with the USA leading the growth trend since the 1950s (Figure 1). Brazil first surpassed the USA in 2019, and grew steadily higher in the following two years. Global production quantity was estimated to be over 380 million metric tons in 2021/22 ^[3]. The top five producing countries (Brazil, the USA, Argentina, China and India) have accounted for over 80% of global production since 2012/13 and reached nearly 90% of the total output in 2020/21 (Figure 2) ^[12].

2. Factors Impacting Soybean Production and Supply Chain

Country-specific agriculture policies dictate crop production output [20]^[13]. The size of the arable land and freshwater resources allocated, the farming system, the choice of crop, and the decision of whether to plant genetically modified (GM) soybean are the important factors directly influencing crop yield, aside from the political and financial considerations and impacts of climate disasters. China hosts ~20% of the world’s population but only possesses 9% and 6% of the world’s arable land and freshwater resources, respectively [21]^[14]. In view of these limitations and the large population in China, staple cereal crops have a higher priority than soybeans. Moreover, the prospect and regulation of the application of GM technology to soybeans has been unclear until the implementation of the revised national “Seed Law” very recently in 2022 (see later sections). The areas in the USA and in Latin American countries under soybean cultivation are 2–3 times larger than those in India and China ^[12]. Larger farm sizes, along with investment, facilitate farm mechanization, allowing farmers to grow more at lower costs. The economics of competing crops among rice, corn, wheat and soybean vary by country and year, causing soybean production to fluctuate annually [22,23]^[15][16]. The USA was first to adopt the cultivation of genetically modified (GM) soybeans. Growing GM soybeans can help generate higher yields and reduce herbicide and pesticide usage [24,25]^[17][18]. Easier cultivation with a lower cost attracts more producers. USA commercialized Roundup Ready^® soybean in 1996. Brazil and Argentina have adopted a similar GM soybean growing model/system with further innovations over the years. More than 90% of the total output from these top three producing countries are GM soybeans. Innovations in genetic modification have driven the rapid growth of soybean production ^[4]. The large-scale production of GM soybeans over the years has also generated concerns about long-term environmental pollution and adverse biodiversity impacts, particularly in the South American Amazon region [26,27]^[19][20]. Until now, China and India have only grown non-GM soybeans for local food consumption (China), oil crushing (India) and minor exports at premium prices (both China and India). Soybean yield in the top three countries is consistently higher than in China. India trails far behind China in total soybean production and yield per unit area despite having a larger area for soybean cultivation [28,29,30]^[21][22][23]. Although both China and India import GM soybeans for oil crushing and feed meals, local acceptance of GM soybeans as food is still low [31,32,33]^[24][25][26]. Debate over GM soybean cultivation also continues in other areas, particularly in the EU [34]^[27]. Good-quality seeds are the basis for successful agricultural production. Assurance of the seed quality using trusted and certified testing methods is critical for planting success. Well-organized production management by providing a proper seed supply to farmers and to markets is even more crucial to realize a significant output. The soybean production supply chain can be divided into three stages: seed breeding, farming, and harvesting and distribution (Figure 3) [3,29,35]^[3][22][28]. At the breeding stage, factors impacting production include basic research and cultivar development by private and public sectors (an elite cultivar will give a good yield if planted properly), cultivar registration, testing and trials, cultivar approval and listing, intellectual property (IP) protection, and cultivar commercialization. Since many new varieties are developed each year, it is essential to have an up-to-date, easily accessible database to provide farmers/buyers with the requisite educational and training information associated with the new varieties. At the farming stage, farmers need to select the right cultivar for maximum yield; optimal adaptation to local geography, climate and soil conditions; and cost considerations. Preparation for sowing needs to include acreage/location planning and cropping considerations (crop rotation or intercropping). Electronic systems/tools for monitoring/recording climate (temperature, rainfall, day length, etc.) and soil (pH and mineral nutrient contents) conditions need to be made available for farmers’ use. Other aspects of management, including the applications of fertilizers, inoculants, herbicides, insecticides and other disease-control measures, also require thorough planning, review and execution to ensure efficiency and maximize economic benefits. At the harvesting and distribution stage, harvesting and processing by mechanical means to minimize loss and reduce cost is critical [36,37]^[29][30]. Harvested seeds are authenticated by various accredited technicians and labs, and they need to be certified/labeled based on their destination for the domestic/international markets. It is critical to ensure that farmers comprehend all the necessary processes and adhere to the established standards and systems. Providing support to farmers to connect them to reliable financial transaction networks will contribute to their success [25]^[18].

3. Rules and Regulations for Seed Quality Assurance

As shown in Figure 3, many parties, influencing factors, standard compliance and delivery steps are involved in the soybean supply chain. The whole supply chain can be complex and confusing. To strengthen the seed sector, it is crucial that seed producers and companies adhere to regulations, rules, policies and standards that have been consequentially established to guarantee quality. Subsequent management and enforcement of the rules and regulations by a centrally coordinated body is paramount for success. An overview of the seed laws, rules, regulations and systems in the top five soybean-producing countries (the USA, China, Argentina, Brazil and India) is displayed in Table 1. Abbreviations: ADM—Asociados Don Mario; AMS—Agricultural Marketing Service; AOSCA—Association of Official Seed Certifying Agencies; ASL—Accredited Seed Laboratory; CAAS—Chinese Academy of Agricultural Sciences; CONASE—Comisión Nacional de Semillas (National Seed Commission); CONICET—Consejo Nacional de Investigaciones Científicas y Técnicas (National Scientific and Technical Research Council); DA&FW—Department of Agriculture and Farmers Welfare; Embrapa—Empresa Brasileira de Pesquisa Agropecuária (Brazillian Agricultural Research Corporation); ICAR—Indian Council of Agricultural Research; ICS—Institute of Crop Sciences; IISR—Indian Institute of Soybean Research; INASE—Instituto Nacional de Semillas (National Seed Institute); INTA—Instituto Nacional de Tecnología Agropecuaria (National Institute of Agricultural Technology); ISTA—International Seed Testing Association; MAGyP—Ministerio de Agricultura, Ganadería y Pesca (Ministry of Agriculture, Livestock and Fisheries); MAPA—Ministério da Agricultura, Pecuária e Abastecimento (Ministry of Agriculture, Livestock and Supply); MARA—Ministry of Agriculture and Rural Affairs; NATESC—National Agriculture Technology Extension Service Center; OECD—Organisation for Economic Co-operation and Development; PRC—People’s Republic of China; USDA—US Department of Agriculture; USPTO—US Patent and Trademark Office. Internationally, several organizations, conventions and treaties exist to deal with the regulation of seed trade. Together, they provide an international regulatory framework to oversee the interests of breeders, producers and buyers. The Organization for Economic Cooperation and Development (OECD, http://www.oecd.org, Seed Schemes, accessed on 14 October 2021) defines Seed Schemes that are globally recognized for the varietal identity and purity of agricultural seeds moving in international trade [38]^[36]. Soybean is under the varietal certification of the Grass and Legume Seed Scheme, Glycine max (L.), Fabaceae family. This scheme lays out the minimum requirements for the soybean seed production procedures, methods and standards, including field inspections and post-control tests [39]^[37]. Currently, over 62,000 varieties from 204 species are under the OECD seed schemes. Sixty countries participate in various schemes, with 54 (including the USA, Argentina, Brazil and India, but not China) in the soybean scheme. OECD appoints a National Designated Authority (NDA) from each participating country to collaborate with other member countries. The International Seed Testing Association (ISTA, http://www.seedtest.org, accessed on 13 October 2021) develops globally recognized standard procedures for seed sampling and testing. The International Union for the Protection of New Varieties of Plants (UPOV, http://www.upov.int, accessed on 1 November 2021) provides the breeders of new plant varieties with intellectual property protection. The International Seed Federation (ISF, http://www.worldseed.org, accessed on 1 November 2021) sets the trade and arbitration rules. The food and Agriculture Organization of the United Nations (FAO, http://www.fao.org, accessed on 14 October 2021) provides the international regulatory framework for related aspects of the seed trade, including plant health and phytosanitary measures, access, and benefit-sharing for plant germplasm and pesticide uses [38,39]^[36][37]. Nationally, each country promulgates its own national seed laws that govern domestic and international seed trades (Table 1). Domestically, each state/province/zone complies with the national principles and implements them with variations to suit local needs. The purpose of the seed laws, rules and regulations is to prevent misrepresentation of the seeds, to ensure good seed quality with agreed-upon testing standards and to check and prevent the spread of weeds/diseases/pests. Ultimately, it is to protect the right of the sellers (breeders, innovators and companies) and buyers (farmers and commercial entities). Hence, the laws include clauses for punishing false representation with penalties and seizure. The national rules and regulations align with international standards and requirements. Additional agreements can also be drawn up separately between individual exporting and importing countries to align with the specific requirements defined by the importing country. USA, as the longest-leading producer of soybean in the past 70 years, instituted a complete set of rules, regulations and systems before 1940. The national seed law is publicized in the U.S. Code of Federal Regulations (CFR), Title 7, Part 201: Federal Seed Act Requirements [45]^[38] with periodic updates. It defines the roles and responsibilities of the regulatory and governing bodies and sets the regulatory framework for seed-production recording, testing, certifying and labeling. Soybean-producing states within the USA comply with the federal laws and could also develop their own detailed practices and standards. The seed laws and regulations in Brazil, Argentina and India follow a similar road map. The regulations in these four countries emphasize seed certification and label information accuracy (USA mandates label accuracy but leaves certification voluntary). China is the only major soybean-producing country that uses an administrative approval/confirmation/permit system with quality data on the label. Verification is performed by spot-check sampling. However, a seed certification system has recently been designed following the OECD seed scheme. Ten selected Chinese provinces tested the draft system with a good outcome. The system is anticipated to be formally implemented in the near future [46,47,48]^[39][40][41].