Wheat on 20 December: late sowing, poor seed and a food-security target
Sunita Devi farms 2.0 hectares in Bareilly district. Her paddy was transplanted late in July and harvested on 12 December, so the field is free only on 18 December. She has 225 kg of certified HD 2967 wheat seed left from last year, stored in a cloth bag in the room where the family also keeps the diesel pump. A germination test on 100 seeds gives 70 seedlings. Her neighbour advises sowing on 20 December with that same seed; the block agriculture officer advises a short-duration variety and a higher seed rate. Canal water will reach her field only in the first week of February, though a tube well can be hired. She also has 65 kg of desi chickpea seed with 90 per cent germination and the option of toria. She wants at least 35 quintals of wheat for the family and a small sale. Normal wheat yield in her village is 45 quintals per hectare, and each day of sowing after about 25 November is generally taken to cost 30–35 kg of grain per hectare.
1. Should she sow wheat on 20 December? Quantify the likely penalty, test it against her 35-quintal target, and compare the alternatives.
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Yes - sow wheat, but immediately and with the right variety, not with HD 2967.
The arithmetic. The delay from 25 November to 20 December is 25 days. At the usual 30–35 kg/ha per day that is 0.75–0.88 t/ha, say 8 quintals, which would leave about 37 q/ha from the 45 q/ha base. On 2 ha that is about 74 quintals, comfortably above her 35-quintal target.
But treat that as an optimistic ceiling. The per-day rule is a linear approximation that holds for moderate delays; once sowing slips past about 20 December, grain filling coincides with the March heat and losses accelerate. Plan on 30–35 q/ha, which is still 60–70 quintals over 2 ha. The target is met; the profit is not, so every input must now earn its place.
Alternatives. Desi chickpea sown on 20–25 December in this zone is a gamble against terminal heat and usually gives only 8–12 q/ha; toria is already past its window. Neither matches wheat for the family's food need. Wheat with a short-duration variety is the best use of the field.
Variety choice. HD 2967 is a medium-to-long-duration type that will flower late and hit heat stress. Switch to a short-duration variety recommended for late sowing in her zone, and confirm the current name from the district agriculture office or KVK rather than from the seed shop.
2. Calculate the seed she actually needs. What should she do with the 225 kg of old seed, and why?
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Step 1 - recommended rate. Timely wheat takes about 100 kg/ha; late-December sowing needs about 125 kg/ha, and sowings after mid-December are often taken to 150 kg/ha to compensate for fewer tillers. Use the official recommendation for her district as the base; assume 150 kg/ha here.
Step 2 - correct for germination. The seed-rate table assumes about 90 per cent germination. Her lot tested at 70 per cent, so the rate must be raised: 150 × (90 ÷ 70) = about 193 kg/ha.
Step 3 - total requirement. 193 kg/ha × 2 ha = about 386 kg. She has 225 kg, which is enough for only about 1.16 ha. She is short by roughly 160 kg.
What to do with the old seed. Do not stretch it across the field and do not mix old and new seed in the same drill, because the two will compete unevenly and the thin patches will be permanent. Buy about 165 kg of fresh certified seed. Two further reasons to distrust the stored lot: a 70 per cent germination figure means the surviving seedlings are also low in vigour, and seed stored in a room with a diesel pump absorbs fumes and moisture, which lowers viability further. If she wants to use some of the old seed despite this, use it on the poorest half-hectare only after re-testing, and treat it with a fungicide or Trichoderma before sowing.
3. List the agronomic adjustments that will make a 20 December sowing work, and identify the single biggest risk in the next 30 days.
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Adjustments after late sowing:
- Sowing: shallow, about 5 cm deep, in rows 15–18 cm apart instead of the usual 22–23 cm. Narrow rows compensate for reduced tillering.
- Nutrition: apply the full phosphorus (about 60 kg P2O5/ha) and potash as a basal dose, because late-sown wheat has less time to build roots. Split nitrogen: a larger share at sowing and at the first irrigation, with the last dose by booting. Late crops respond to early nitrogen, not to a late dose.
- Weed control: fewer tillers means weeds are relatively more damaging. Use a pre-emergence herbicide such as pendimethalin at sowing, or an early post-emergence product, and hand-weed the patches the drill missed.
- Variety and harvest: choose a short-duration variety and plan to harvest as soon as the crop is ready, before the April heat shrivels the grain.
The biggest risk in the next 30 days: water at the crown-root stage. The crown-root initiation irrigation falls at about 20–25 days after sowing, which is around 10–15 January. Canal water arrives only in the first week of February, which is too late. She must book the tube well now for one irrigation at CRI and budget for it, because skipping CRI on a late-sown crop removes most of the remaining yield. A light pre-sowing irrigation to wet the seedbed is also worth the money. Line up a second tube well irrigation for flowering.