Soybean
Soybean Cultivation Guide: Sowing, Seed Rate & Crop Care
Step-by-step soybean (soya) cultivation — seedbed preparation, sowing time, seed rate and spacing, Rhizobium seed treatment, irrigation at critical stages, nutrition and weed control for high yield.
By the Varsha Seeds Agronomy Team · Updated Fri Jul 03
Soybean rewards two things above all: a firm plant stand and a healthy root nodule system. Get the seed rate, seed treatment and drainage right, and this short-duration Kharif oilseed-cum-pulse delivers both income and a nitrogen-richer field for the crop that follows.
Soil and seedbed preparation
Soybean prefers a well-drained loam to clay-loam with good organic matter and a near-neutral pH. The one condition it will not tolerate is waterlogging — even short spells of standing water kill nodules and rot roots. Give one or two ploughings and planking for a fine, level bed, and plan drainage channels before sowing in heavier soils.
Sowing time, seed rate and spacing
- Season: Kharif — sow late June to early July with the monsoon
- Sow on rain: wait for 50–75 mm of rain to wet the soil to root depth
- Seed rate: ~60–75 kg/ha (use the higher end for bold-seeded types)
- Spacing: about 45 cm between rows × 5 cm between plants
- Depth: 3–4 cm — never deeper, as soybean pushes up cotyledons
Sow in lines to the correct depth. Deep sowing and crusting after rain are the two most common causes of a thin stand.
Seed treatment and inoculation
This is the step that separates an average soybean crop from a good one:
- Fungicide first — treat seed against seed- and soil-borne diseases and damping-off.
- Then Rhizobium — inoculate with the correct soybean Rhizobium culture for strong nodulation and free biological nitrogen.
- Handle treated seed gently and sow the same day; the seed coat is fragile.
Irrigation at critical stages
In a normal monsoon soybean is largely rainfed, but the crop must not miss water at its two most sensitive stages:
| Stage | Why it matters |
|---|---|
| Flowering | Water stress causes heavy flower drop and fewer pods |
| Pod filling | Determines seed size and final yield |
Just as important, drain excess water after heavy rain — a day of standing water at flowering does more damage than a short dry spell.
Nutrition
Because soybean fixes much of its own nitrogen, it needs only a small starter dose of nitrogen plus adequate phosphorus and potash, applied basally on the basis of a soil test. Phosphorus in particular drives root and nodule development, so do not skip it. Sulphur benefits oil content in most soybean soils.
Weed control
The first 30–45 days are the critical weed-free period — soybean is a poor early competitor. Control weeds with a pre-emergence herbicide and/or timely inter-cultivation so the crop, not the weeds, uses your moisture and nutrients.
Putting it together
Sow on good rain in lines at 3–4 cm, use a full seed rate of treated, inoculated seed, keep the first six weeks weed-free, protect flowering and pod filling from both drought and waterlogging, and feed phosphorus generously. For the wider pulse picture see the moong, urad & soybean pillar guide, plan your season with the Kharif sowing calendar, and consider 3035 research soybean for a strong, well-adapted crop.
Frequently Asked Questions
What is the seed rate for soybean?
Use about 60–75 kg/ha of good soybean seed, adjusting for seed size and germination. Bold-seeded varieties need the higher end of the range. Always sow on a germination test — soybean seed is delicate and loses viability quickly if stored badly.
When should soybean be sown?
Soybean is a Kharif crop sown with the monsoon, from late June to early July, once 50–75 mm of rain has wet the soil to root depth. Avoid very late sowing, which shortens pod filling and cuts yield sharply.
Why treat soybean seed with Rhizobium?
Soybean fixes its own nitrogen through Rhizobium bacteria in root nodules. Inoculating the seed with the correct Rhizobium culture (with a fungicide seed treatment first) improves nodulation, reduces nitrogen cost and leaves the soil richer for the next crop.
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