Worldwide, the soybean is one of the most important legumes. With an area under cultivation of 93,000 hectares, Austria is the fifth-largest soybean producer in Europe.
In times of a more conscious, meat-restricted diet, the soybean is becoming increasingly important as a protein supplier for humans and is also an important protein supplier in animal feed.
Soybeans were an important food crop in China and other Asian countries thousands of years ago. Nowadays, the seeds are used cooked as a vegetable (vegetable soybean, green soybean, edamame), or processed into soy milk, flour or tofu; it is also used as an emulsifier in the production of cooking oil, margarine, baked goods and much more.
The soybean is also an important protein feed, mainly used in toasted, pressed or extracted form (toasted soybean, soybean press cake or soybean extraction meal). These products are high quality feeds, as the protein of the soybean has a high biological value. For better digestibility and usability of the protein, heat treatment of the beans such as toasting is necessary.
The annual plant grows up to 100 cm high with its erect stem. Most varieties have a so-called determinate, i.e. limited, growth and are usually self-pollinating. However, the activity of bees or other pollinators has a positive influence; there is even pure honey.
The soybean is actually a short-day plant, so there must be a correspondingly long dark/night phase to trigger flower formation. Therefore, harvesting was only possible very late in the year. Through breeding, the short-day character has been significantly reduced and today's soybean varieties are harvested as early as September, depending on the maturity group and climatic region.
Typical of the family, the soybean has a butterfly flower with a corolla of shuttle, flag and wing, the ten stamens fused into a tube. The corolla is small, only slightly longer than the calyx, and thus quite inconspicuous. Their coloration ranges from white to purple. Three to eight, sometimes twelve flowers are arranged together in clusters in the leaf axils.
The fruits are hairy pods up to 8 cm long and about 10 mm wide, usually with two to three seeds. The round to ovoid seeds are smooth and yellow to brown in color.
The home of the parent species, Glycine soja, also Glycine ussuriensis, is East Asia. The main cultivation areas of the cultivated form, Glycine max, are now in the USA, Brazil and Argentina.
In Austria, soybean acreage reached a new record high of 93,000 ha in 2022, with an estimated half going directly to food production. This acreage makes Austria the fifth largest soybean producer in Europe.
The soybean prefers a warm, humid climate. In Austria, it thrives best in the (south) east of the country and therefore copes well with the changing climate.
For good growth, the plants need loose, well-aerated, slightly acidic to neutral (pH 6.5 to 7.5) soils with good water-holding capacity. Water requirements are high, especially during flowering and grain formation.
Suitable preceding crops include winter cereals, but also summer cereals and grain corn. Since soybeans are weak in competition due to their slow youth development, it is particularly important that the preceding crop suppresses late-germinating weeds and should not promote uncontrollable nitrogen releases. Soybean, while self-tolerant, should only be grown every four to five years in succession due to the risk of the fungal disease Sclerotinia. The same sequence applies to other legume species, such as beans, clovers, peas, etc., and other crops susceptible to Sclerotinia (canola, sunflower, several vegetables). As a nitrogen collector and a plant with a good root system to improve soil structure, soybean itself is a good preceding crop.
The sowing period is between mid-April to early/mid-May at a soil temperature of 10 °C. Seeding can be done with a drill or precision drill.
Soybean lives in symbiosis with nitrogen-fixing nodule bacteria (Rhizobium japonicum), which must be applied to the seed when soybean is first grown. They meet the plant's high nitrogen requirements. Normally, therefore, no nitrogen fertilization is necessary; higher nitrogen applications even impair the activity of the nodule bacteria.
Finally, harvesting time depends on the variety and weather conditions and is between mid-September and the end of October. Maturity begins with the yellowing of the leaves, which eventually dry up and fall off. The beans become round and firm and lie freely in the pod (rattling when shaken). Harvesting is usually done a few days after leaf fall with a combine, and the beans should have a water content of 12 to 16%. Average yields are 1,800 to 3,000 kg/ha.
Last updated: 14.03.2023