Maize (corn) is the second-largest grain seaborne cargo after wheat, with global seaborne trade of approximately 180 to 200 million tonnes per year. The cargo is principally moved from major exporting regions (United States, Brazil, Argentina, Ukraine) to import markets including China, Mexico, Japan, South Korea, the European Union, and Egypt. Maize is regulated under both the International Code for the Safe Carriage of Grain in Bulk (the International Grain Code) and the IMSBC Code under the same framework as wheat.
Cargo properties
Maize is supplied as whole kernels with bulk density of approximately 0.7 to 0.78 tonnes per cubic metre, with stowage factor of approximately 1.3 to 1.4 cubic metres per tonne — slightly higher than wheat. Moisture content at loading is typically 12 to 15 per cent. The cargo is non-toxic, non-flammable, and not classified as a hazardous chemical cargo. Specific carriage hazards include grain shifting, self-heating from elevated moisture, insect infestation, and dust explosion risk during handling.
The principal commercial grades shipped by sea are:
- Yellow dent: the dominant US, Argentine, Brazilian, and Ukrainian export grade. Used principally as animal feed and as ethanol feedstock in domestic markets.
- White maize: a smaller volume grade with food applications, particularly in African markets.
- Specialty grades: high-amylose, high-oil, and food-grade maize for niche industrial applications.
Major routes
Maize seaborne trade flows include:
- United States to Mexico, Japan, South Korea, China: the largest single trade lane, with US Gulf (New Orleans, Houston) and Pacific Northwest (Portland) export.
- Brazil to China and Asia: rapidly growing trade since the 2010s, with Brazilian production overtaking the US in some years. Brazilian export through Paranaguá, Santos, and Itaqui.
- Argentina to South America, North Africa, and Asia: Bahía Blanca and Rosario export.
- Ukraine to Europe, Middle East, and Asia: significant trade severely disrupted since 2022 but partially restored.
- Russia to selected markets: smaller volumes than wheat.
China is the dominant single growth market, having transitioned from a maize self-sufficient producer to a major importer principally to support its expanding livestock industry.
Carriage requirements
Bulk maize shipments follow the same carriage framework as wheat:
- International Grain Code stability calculations and trimming.
- IMSBC Group C handling provisions.
- Pre-loading moisture content certification.
- Fumigation procedures where applicable.