SOYA

Family: Leguminosae (sub family: Papilionoideae)

Genus: Glycine

Species: max

(i) General background on the plant

A bushy and rather coarse annual herb originating in China where it is a long-established cultivated plant, as in other East Asian countries. Since 1945 it has become the most important world protein and oil crop. The stems are up to 1.8 m tall and it is sometimes vine-like. The axillary irregular racemes are often leafy and short (10 - 35) with 5 - 8 flowers. The corollas are white, pink, greenish blue, violet or purple and 4.5 - 7 mm long., The pods are oblong, 25 - 75 mm long, 8-15 mm broad, yellowish brown, with bristly hairs. There are 2-3 seeds per pod which are ovoid to sub-spherical, 6 - 11 x 5 - 8mm in size and greenish cream or greyish-olive to reddish black, and smooth.

(ii) Details of quality characters

Seed composition:

Soybean oil consists of :

Palmitoleic acid (C16:1) 11.7%

Stearic acid (C18:0) 2 - 6%

Palmitic acid (C16:0) 2 - 10%

Oleic acid (C18:1) 23 - 32%

Linoleic (C18:2) 48 - 52%

Linolenic (C18:3) 2 - 12%

and 5.5% C20 to C22 acids including arachidonic acid. It is a light yellow oil with a bland flavour.

A globular protein, glycine, accounts for 80-90% of the total protein content of the seed and in turn is made up of the following amino acids:

Cystine 1.1%

Methionine 1.8%

Lysine 5.4%

Tryptophan 1.7%

Threonine 2.1%

Leucine 9.2%

Isoleucine 2.4%

Phenylalanine 4.3%

Tryosine 3.9%

Histidine 2.2%

Valine 1.6%

Arginine 8.3%

Glycine 0.7%

Alanine 1.7%

Aspartine 5.7%

Glutamine 19%

Proline 4.3%

(iii) Current production - crop statistics

(Source FAO 1996)

5 t hay/ha on average.
*1,700- 3400 kg beans/ha world average, in extremely favourable conditions 4t/ha can be achieved.

(iv) Constraints on production

The optimal temperature for growth is 30°C. Soya is very sensitive to photoperiod and most cultivars will only bloom when daylength is less than 14 hours, it will also not set seed if night temperatures fall below 10°C. Very short days will lead to premature flowering producing small plants and reduced yields. Soya beans are placed in 13 maturity groups, 000 (earliest) to X, based on their response to photoperiod. The 000 cultivars are adapted to to the northern- and southern-most world production areas.

Most soya bean cultivars are adapted for full season growth in a narrow 160 - 240km band. Successful seed set occurs when night temperatures reach 21°C followed by days of at least 27°C. In the main growing areas the growing period is 4 - 5 months. In warmer countries 500 - 750mm rainfall is necessary for good yields, and it should not rain too much when pods are ripening.

(v) Markets and market potential

Soya beans are an important source of oil and protein to the world. Its main uses worldwide are for the production of margarine, also as a vegetable oil after refining and partial dehydrogenation. The edible semi-drying oil has food and industrial uses. Soya flour from whole beans contains 20% oil with 95% of the oil extracted from the flour can be used in baking, as additives and extenders to cereal flour and meat products, and in health foods. Soya has a high content of lecithins (1.1 - 3.2%) which are used as emulsifiers in the food industry, pharmacy, decorating materials, printing inks, pesticides.

Protein in the extraction meal is used for human and animal food, also synthetic fibres, glues, foams, foam-forming agents.

The unripe seeds are eaten in East Asia and the USA as a vegetable. When ripe they are difficult to digest as they contain toxic compounds and have an unpleasant taste, it is unlikely therefore that soya beans will have a role as a new foodstuff as they have to be soaked and cooked for a long time before they are edible. Other valuable foods obtained from soya are soy sauce, soya milk and tofu. Also soya bean sprouts are an important food source in East Asia.

The vegetative portions of the plant can be used for grazing or as hay/fodder/silage or as a green manure. The straw can be used to make paper, stiffer than that from wheat straw.

There are many old / folk medicinal uses.

(vi) Other information

Cultivation of soya bean offers few problems - moisture, soil and temperature requirements are similar to those of maize. Seedbed is prepared as for maize or cotton - a thoroughly cultivated deep loose seedbed prepared immediately before sowing in autumn or spring is required. Soya beans require 50% (dry weight) moisture content for germination, therefore a good supply of moisture is critical at planting time. Sown at the same time or after that for maize. Full season varieties give largest yields. Seed is sown at row spacing of 60 - 90 cm and within-row spacing of 10 - 15cm between seeds encourages growth, also aids weed control which is important during establishment. Soya beans grow best between soil pH 5.8 and 7.0, in a range of soil types.

Seeds are treated to protect from soil-borne diseases. Soya bean is symbiotic with rhizobium and inoculation of seeds with the correct strain of a commercial culture of nitrogen fixing bacteria is essential, unless these bacteria are known to be in the soil. They do not need to be inoculated if nodulated soybeans have been there in the previous 4-5 years. Inoculants from other legumes are ineffective. Nitrogen fixing is very active so on most soils no additional nitrogen fertilizers are necessary. High soil temperatures reduce N₂ binding potential of nodules, hence in hot sunny areas seed should be sown densely to provide a leaf canopy rapidly. In absence of nodulation, nitrogen fertiliser is required for maximum yields. Other fertilisers are also critical and need to be adjusted according to soil fertility and cropping.

Weed control: Use early cultivations and between the row cultivations until a time where cultivations will damage the crop. Chemical weed control agents can be used. Weed control is important as yield can be halved in its absence.

Although tolerant of drought, adequate moisture is important during pod filling.

Major losses due to diseases can largely be controlled with the use of resistant cultivars, sanitary measures and crop rotation. Losses can be incurred by Pseudomonas syringae pv. glycinea (bacterial blight) and Diaporthe phaseolorum (pod and stem blight), soybean mosaic virus (SbMV). The leaf eating beetle Plagiodera inclusa and the soya bean moth, Laspeyresia glycinivorella can cause considerable loss and control by insecticides is necessary.

Harvest: The beans mature at the same time. Maturity is accompanied by dropping of the leaves and drying of the stems. Harvesting can be carried out by combine harvesters. Combines are continuously adjusted during combining to reduce splitting and mechanical damage to the seeds - losses of 10-20% can occur. Seeds are very sensitive to combining damage below 12% moisture content (mc). To store for up to a year, reduce mc to below 11%. To store for up to 5 years, reduce mc to below 10%.

In the United States the agrochemical firm Monsanto has produced glyphosate-tolerant (Round-up Ready) cultivars of Soya bean by genetic engineering techniques. In the US in 1997 3,645,000ha were planted with Round-up Ready soya. The planting of Round-up Ready soya in Europe is yet to be approved.

See the following pages in the NF-2000 Database

AGRE-0039 - Seed Oils for New Technical Applications SONCA

FAIR-1625 - New Valorisation of Rapeseed/Sunflower Lecithins, in Cosmetic and Fermentation Industries - AVAIL

FAIR-3026 - Fractionation of lucerne juice to create nutritional and functional protein ingredients for food and non-food industry

FAIR-PL97-3884 - CTVO-NET Chemical-technical utilisation of vegetable oils

FAIR-PL97-3527 - Exploitation of the unique genetic variability of peas in the production of food and non-food ingredients

(vii) Contacts

American Soya Association.

(viii) References

CRC Handbook of Alternative Cash Crops; Duke, J. A., duCellier, J. L. Published 1993 by CRC Press, Inc USA.