Soybean

Soybean combines a relatively high seed protein and oil content with the ability to supply part of its own nitrogen needs through symbiotic fixation, which distinguishes it agronomically from cereal crops grown in rotation with it.

Production ranges from smallholder systems to large mechanized operations, and soybean is commonly grown in rotation with cereals such as maize. Agronomic detail such as maturity group selection and planting date is set locally according to latitude and season length.

Family

Fabaceae (legume family)

Genus and species

Glycine max

Growth habit

Bushy annual with trifoliate leaves, producing pods that typically contain two to four seeds

Root system

Taproot bearing nodules that host nitrogen-fixing Bradyrhizobium bacteria

Soybean was domesticated in East Asia from its wild relative Glycine soja and was cultivated in China for millennia before spreading to other parts of Asia. It was subsequently introduced to other continents and expanded rapidly during the twentieth century as an oilseed and feed crop.

Soybean is now grown across the Americas, Asia, and increasingly other regions. Current data on planted area, production, and trade by country are compiled by FAO and national agricultural statistics agencies and should be taken from those primary sources.

Soybean is a warm-season crop typically grown where a sufficiently long frost-free period is available. Flowering is triggered by day length in many varieties, so maturity groups are matched to local latitude to ensure the crop flowers and matures within the growing season.

Heat and moisture stress during flowering and pod fill can reduce seed set and yield, which is one reason planting date and variety maturity are chosen carefully for local conditions.

Soybean performs well on deep, well-drained loams with good structure. It is sensitive to waterlogging and compaction, both of which restrict root and nodule development and can increase the risk of root and stem diseases.

In fields without a recent history of soybean production, seed is often treated with a rhizobial inoculant to ensure effective nodulation. Maturity group, row spacing, and seeding rate are set according to local latitude, soil, and equipment.

• Maturity group selection matched to local day length and season length
• Inoculation with compatible Bradyrhizobium strains in fields new to soybean production
• Crop rotation, commonly with cereals such as maize, to manage pests, diseases, and soil structure
• Weed management during early growth, before the canopy closes

Effective nitrogen fixation can supply a substantial share of the crop nitrogen requirement, though this depends on successful nodulation and soil conditions. Phosphorus and potassium remain important, particularly on soils with limited native supply, and requirements depend on soil tests and target yield.

Soybean is grown both rain-fed and under irrigation. Water demand is highest during flowering and pod fill, and moisture stress during this period can noticeably reduce yield.

Where irrigation is used, scheduling is generally based on estimated crop evapotranspiration and local climate data, following methods published by FAO and national agricultural agencies.

Soybean is affected by root and stem rot diseases associated with several soilborne fungi and oomycetes, particularly under wet or compacted soil conditions, as well as by foliar diseases whose importance varies by region. The soybean aphid and other insect pests can reduce yield and, in some cases, transmit viruses.

Management typically combines resistant varieties, crop rotation, drainage improvement, field monitoring, and, where warranted, locally authorized control measures used according to their labels.

Soybean is harvested once pods and seeds have matured and dried to a moisture content suitable for combining and safe storage. Harvest timing balances yield and quality against the risk of pod shattering and weather-related losses.

• Crushing into vegetable oil and high-protein meal for livestock feed
• Food products including soy milk, tofu, and fermented foods in some cuisines
• Whole or processed soybeans used directly in animal feed rations
• Industrial applications such as biodiesel feedstock in some regions