Soybean

Soybean (Glycine max), called soya bean across Pakistan, is the world’s largest oilseed and a high-protein pulse that doubles as a soil-builder. POWO records it native to temperate East Asia from Russia’s Far East through China,¹ but it now grows in every major farming country. For a food-forest grower on the Punjab plains, the Pothohar plateau, or the lower KPK hills, soybean is the summer legume worth trialling alongside the established Pakistani crops of mungbean and mash.

Where it thrives

Feedipedia frames optimal conditions as average day temperatures near 30 degrees Celsius, 850 mm of annual rainfall, and at least 500 mm of water during the growing season, between latitudes of 53 degrees north and south, up to 2000 metres elevation.² Soybean prefers soils between pH 5.5 and 7.5 with good drainage, is sensitive to acidity and aluminium toxicity, and tolerates only brief drought or waterlogging.² NC State Extension records it as a rapid-growing annual one to two feet tall preferring full sun and well-drained loam.³ Pakistan’s Pothohar rainfed belt and the irrigated Punjab plains both suit the autumn-sown crop, with Faisalabad and the Barani Agricultural Research Institute Chakwal having released cultivars adapted to local heat.

Role in the system

Soybean sits in the groundcover stratum as a short-season pioneer with a strong fertility job. It nodulates with Bradyrhizobium japonicum, which is not native to Pakistani soils, so seed inoculation is the single decision that decides whether a first crop fixes meaningful nitrogen or fails quietly.² Once nodulated it serves well as a rotation legume ahead of wheat, maize or cotton, and it has the practical bonus of suppressing the parasitic weed Striga hermonthica.² In a young food forest, slot it under deciduous fruit trees during their summer flush, or as a strip crop along a windbreak edge.

Growing it

Sow inoculated seed three to four centimetres deep once soil temperatures reach 22 degrees and night minimums stay above 15 degrees — for most of Punjab that means a kharif sowing in late June or July, or a spring sowing in March on the Pothohar.³ Space rows 45 to 60 cm apart with plants 5 to 10 cm in the row, aiming for 300 to 400 thousand plants per hectare. Choose Pakistani-released cultivars such as Ajmeri, NARC-1 or Faisal Soybean rather than imported feed-grade seed, which struggles with daylength and heat. Hand-weed or shallow-hoe in the first six to eight weeks before the canopy closes; after that the crop suppresses weeds on its own.² Hold off heavy nitrogen — too much suppresses nodulation. Harvest at 90 to 130 days when pods rattle and leaves drop.

What you get

Global average yields run near 2.25 t/ha, with well-managed irrigated plots in similar climates reaching 3 t/ha.² Seed carries about 40 percent protein and 20 percent oil — the highest combined protein-oil profile of any common pulse, which is why it anchors the global feed and edible-oil trade.² Whole roasted soybean enters Pakistani diets as a snack and as soya keema; isoflavones in the seed — genistein and daidzein — are linked in clinical reviews to reduced LDL cholesterol, lower type 2 diabetes risk, and improved bone density in post-menopausal women.⁴ Aerial residue feeds livestock or composts back to the bed.

Sourcing notes

The non-negotiable purchase is a fresh B. japonicum inoculant, sold by NARC and several Punjab seed houses; without it the crop behaves like a poor-feeding cereal. Good companions are maize or sorghum on neighbouring strips and a brassica cover after harvest to use the residual nitrogen. Keep soybean out of any plot that grew mungbean or peanut the previous season to break the shared charcoal-rot complex.

Sources

1. Royal Botanic Gardens, Kew (2024). “Glycine max (L.) Merr.” Plants of the World Online.
2. Heuzé, V. et al. (2017). “Soybean (general).” Feedipedia, INRAE-CIRAD-AFZ-FAO.
3. NC State Extension (2024). “Glycine max (Edamame, Soy, Soybean).” North Carolina Extension Gardener Plant Toolbox.
4. Kang, J.H., Dong, Z. & Shin, S.H. (2023). “Benefits of Soybean in the Era of Precision Medicine: A Review of Clinical Evidence.” Journal of Microbiology and Biotechnology.