Soybean
Soybean (Glycine max (L.) Merr.) is unique among the other food legumes because it would be used as a cheap source of protein. It has a good potential to promote as a commercial crop in Sri Lanka. It can be processed in to a wide range of food products for human consumption, such as textured vegetable protein (TVP), soy curd (tofu), soy ice cream, soy source, soy milk and soy oil. It is widely used as a vegetable protein among Sri Lankans. Soybean contains 35.1 % of protein and it is highly nutritious and beneficial to human health and used in production of poultry feed as a raw material in supplementing the protein. The major constituents of soybean seeds are protein and oil. It can be classified as an oil crop due to the high oil content (15-20%).

Extent and production 1961 to 2013



Areas Cultivated
Soybean can be cultivated both in the Dry and Intermediate zones of Sri Lanka, but cultivation is limited to Anuradhapura district and System H of the Mahaweli Irrigation scheme and small extent is cultivated in Kurunegala, Matale and Polonnaruwa districts. This crop is cultivated on a limited scale in paddy fields as well as in up lands in both yala (dry) and maha (wet) seasons. Yala season is the main soybean growing season and most of the farmers cultivate under supplementary irrigated conditions in paddy fields whereas in maha, it is cultivated under rainfed conditions in uplands.


Nutritional value

Soybean is rich in protein and oil. Protein content of the Soybean can be as high 40% with the fat reaching even 22%. Fiber content of the Soybean can be around 9 %.

Proximate analysis of whole Soybean

Nutritional Values of Soybean (per 100g)

Moisture

8.5 g

Protein

36.5 g

Carbohydrates

30.2 g

Fat

19.9 g

Ash

4.9 g

Recommended Varieties
Varietal Characteristics
MISB 01
It has cream colour shiny seed coat with brown colour hilum. It is similar in seed size to Pb 01, with a maturity period of 90 days and an average yield of over 3.0 t/ha. It is tolerant to shattering, lodging and good nodulation ability compared to Pb 01. In addition it is tolerant to Bacterial pustules (Xanthomonas phaseoli var. sojensis), which is one of the major diseases reported in the world. Variety MISB 01 has 13 g of 100 seed weight while Pb 01 has 12 g of 100 seed weight.

Pb-1
It is an introduction from India and is a selection from variety Nanking. It shows an erect growth with a plant height of around 50-60 cm. It flowers in 25-35 days after planting. Flowers are purple in colour. Pods are tan in colour Its medium sized seed have a thousand seed weight of about 155g. Seed are cream in colour with a buff coloured hilum. This mature in about 80-85 days after planting. Variety Pb-1 is suitable for rainfall uplands during the maha season as well as with supplementation irrigation during the yala season. Average yield 1700-2000 kg ha-1. Seeds of this varieties Pb-1 has on oil content of 20% a protein content of 40%.

PM-13
This variety resembles Pb-1 in many respects. It exhibits an erect growth with a plant height of 50-60 cm. Flowering occurs in 30-35 days after sowing. The flowers are purple in colour. Pods are tan in colour when day. Suds are cream coloured with a buff in coloured hilum. They are medium sized and 140g on thousand seed weight. The varieties matures in about 90-95 days after sowing. A seed yield of 1700 - 2100 kg ha-1 can be expected from this variety. Its seeds posses a high protein content of 49% an oil content of 18% seeds retain. Availability above 80% for a period of about 4-6 mounts under ambient humid tropical conditions.Recommended Varieties
Field Establishment
Climatic Requirements
Soybean can be grown in most agro-climatic regions but preferred areas are Dry zone and drier pats of the intermediate Zone.

Soils
Almost any soil with a pH of 6-7 is adequate, but excessive moisture is not acceptable. Soybean tolerates a degree of poor drainage. Highlands in maha and well-drained paddy fields in yala are preferable for Soybean cultivation. It can also be grown on highlands during yala if there is sufficient soil moisture

Land Preparation
One ploughing followed by a harrowing and shape into furrows & ridges. Ridges should be formed 40-50 cm apart to facilitate irrigation. Seed rate is 50Kg/ha.

Time of Planting
Maha - Mid October - Mid November
Yala - Mid April - End May

Method of Planting
Plant on a flat surface if soil drainage is good and on ridges or raised bed when drainage is poor. Plant not more than 3 cm deep at 5 cm intervals in row 40 cm apart. 40 cm x 5 cm, 1 plant /hill.
Crop Management
Fertilizer
Basal
Urea 50 kg/ha
Triple super phosphate 100 kg/ha
Muriate of potash 75 kg/ha
Top dressing 50 kg urea at the onset of flowering

Irrigation
Irrigation once in every 4 days during the first month, then 6-7 days until about 3 weeks before harvest when irrigation should be stopped.

In flat bed planting, flood the beds, in ridge and furrow and raised bed systems flood the furrows. Moisture stress must be avoided during flowering and pod filling.

Weed control
Apply one of the following pre emergence herbicide just after planting for control of weeds for 2-3 weeks
Metribuzin 70% WP/WG (sencor) 1 kg/ha
Methabenzthiazuron 70% WP 3.5 kg/ha
Metolachlor 500g/lEC 4.0 l/ha
Disease
Purple Stain(Cercospora Kikuchi)
Symptoms
Seed discoloration varies from pink to dark purple and is often accompanied by cracks in the seed coat. Infected seed produces diseased seedlings with angular reddish brown stops on leav and often results in seedling death.
Control
Use disease free seed
Treat seed with a fungicide
Use a recommended fungicide as a foliar spray at pod set

Bacterial Pustule (Xanthomonas phaseoli var. sojensis)
Symptoms
Minute pale green spots on both leaf surfaces become brown pustules with a yellow halo
Irregular dark brown patches appear when lesion coalesce
Control
Plant disease free seed
Use crop rotation

Yellow Mosaic Virus
Control
Spray an insecticide for white fly control
Destroy weed which habour the virus
Use disease free seeds

Bud Blight (a virus)
Symptams
Necrosis and curving of the terminal bud to form a crook, buds become necrotic and fall off
Discoloration develops on the stem and branches near and bases of petioles
Natural senescence is delayed, plants remain green at harvest if infection occurs at later stages of growthx
Plant die in severe attacks
Control:-
Remove infected plants
Plant disease free seed
Control weeds

Charcoal Rot (Macrophomina phaseolina)
Symptams
Reddish brown discoloration of emerging seedlings
Dark brown to black discoloration at the base of the stem in young plants
Small black bodies of selerotia are visible when the epidermis of the discolored area is removed Leaves turn yellow and wilt.
Control
Flood the feild 3-4 weeks before planting
Avoid excessive seed rate
Amend soil with the organic matter several weeks before planting
Period a balanced fertilizer to encourage vigorous growth
Rotate crops
Harvesting & Post-harvest Technology
Yield
Yield potential under irrigated condition 3000Kg/ha, rainfed condition 2000Kg/ha

Harvesting
1. The crop should be harvested when leaves turn yellow and drop and when 95% of the pods have turned straw color
2. Cut plant with a sickle & sun dry.
3. Thresh it by trampling by tractor or beating with wooden sticks or using a theresherer
4. Seed for planting must be threshed carefully to avoid seed damage.
5. Separate and clean the grains by winnowing.

Post harvest handling
Sun dry seeds for 2-3 days to lower moisture content to about 10-12%.Soybeans for seed should be dried to 9%. Cool sun -dried seeds for 2-3 hours before bagging, then store in a cool, dry place.