Soybean (Glycine max)

1. Origin and History

• Origin: East Asia (mainly China).
• Domestication: >5000 years ago.
• Spread: To Japan, Korea, and later Europe (18th century).
• India: Introduced in early 20th century, but commercial popularity began in 1970s with AICRP on Soybean.

2. General Information

• Major oilseed crop of the world.
• Contributes ~50% of global oilseed production.
• Supplies ~60% of world vegetable protein and 30% of vegetable oil.
• Known as “Wonder crop” and “Meat for the poor”.
• Richest, cheapest, and most accessible source of high-quality proteins and fats.

3. Botanical Features

• Family: Leguminosae.
• Prophylls: Tiny paired simple leaves (<1 mm) at base of lateral branches.
• First nodules: Appear ~10 DAS.
• Photosynthesis: C₃ type.
• Root nodulation: Effective with Rhizobium japonicum.

4. Area, Production & Distribution (India, 2023)

• Area: ~12 million ha.
• Top states: Madhya Pradesh > Maharashtra > Rajasthan > Karnataka.
• Leading districts: Indore, Ujjain, Nagpur belt.
• India’s rank: 5th globally (after USA, Brazil, Argentina, China).
• Export: Mainly soymeal for poultry & livestock feed.

5. Chemical Composition

• Oil: ~20% (rich in unsaturated fats).
• Protein: ~40% (lysine-rich, methionine-poor).
• Fatty acids:
  • Linoleic acid: 56–60%
  • Oleic acid: 30–35%
  • Linolenic acid: 5–10%
  • Saturated FA (palmitic + stearic): 12–14%
• Amino acids:
  • High: Lysine (6.2%), Tryptophan (1.4%)
  • Low: Methionine (1.2%), Cystine (0.8%)
• Vitamins: Good source of B-complex.
• Special property: Iodine value ~140 (high unsaturation).

6. Climatic Requirements

• Temperature: 20–30°C optimum.
• Rainfall: 600–1000 mm (well-distributed).
• Photoperiod: Short-day (12–14 hrs darkness).
• Soil: Well-drained loam to clay loam, pH 6.0–7.5.
• Sensitive to: Waterlogging, salinity.

7. Agronomy (Cultural Practices)

• Season:
  • Kharif: June–July (main season).
  • Spring: Feb–March (limited areas).
• Seed rate: 75–80 kg/ha.
• Spacing: 45–60 cm × 5–10 cm.
• Sowing depth: 3–5 cm.
• Fertilizer requirement:
  • N: 20–30 kg/ha (starter dose).
  • P₂O₅: 60–75 kg/ha.
  • K₂O: 30–40 kg/ha.
  • Sulphur & micronutrients (Mo, Zn) improve quality.
• Biofertilizer: Inoculate with Rhizobium japonicum + PSB.
• Irrigation: Drought-sensitive, critical stages → flowering & pod filling.

8. Weed Management

• Critical period: 0–45 DAS.
• Cultural: 2 hand weedings (20 & 40 DAS).
• Chemical control:
  • Nitrofen (TOK-25): 1.5–2.0 kg a.i./ha (PE).
  • Fluchloralin (Basalin): 1.0 kg a.i./ha (PPI).
  • Metribuzin (Sencor): 1.0 kg a.i./ha (PE).

9. Pests and Diseases

• Insect pests: Stem fly → systemic insecticides. Girdle beetle → damages stems & pods.
• Diseases: Rust → Mancozeb, resistant varieties. Root/stem rot → crop rotation, drainage.
• Integrated management: Seed treatment + resistant varieties + need-based sprays.

10. Quality & Industrial Use

• Nutritional: High protein (40%), oil (20%), lysine-rich.
• Edible forms: Soy milk, tofu, soy flour, soy nuggets.
• Industrial: Oil for soaps, paints, lubricants, biodiesel.
• By-product: Soymeal → protein-rich animal & poultry feed.
• Note: Not used as dal (lipoxidase enzyme causes off-flavour).
• Antinutritional factors: Trypsin inhibitors, hemagglutinins, oligosaccharides (destroyed by heat).

11. Economics

• Moderate cost of cultivation.
• B:C ratio = ~1.8–2.2 (higher under irrigated).
• Contributes significantly to foreign exchange via soymeal exports.

12. Post-harvest Technology

• Harvesting: At ~95% maturity, pods yellow, leaves drop, seeds rattle.
• Threshing: By thresher or combine.
• Drying: Seeds dried to 10–12% moisture.
• Storage: In silos/gunny bags under dry, aerated conditions.
• Processing: Oil extraction → refined oil; cakes → feed; protein products → value-added foods.

13. Quick Recap (MCQ Pointers)

• Botanical name: Glycine max.
• Origin: East Asia (China).
• Oil content: ~20%.
• Protein content: ~40%.
• First nodules: 10 DAS.
• Linoleic acid: 56–60%.
• Pre-emergence herbicides: Nitrofen, Metribuzin.
• Sowing depth: 3–5 cm.
• Major pest: Stem fly.
• Major disease: Rust.