Mustard Sowing and Fertilizer Schedule for High Oil Yield

Mustard needs much more sulphur than cereals like wheat, because sulphur is used to build the oil and protein in the seed. A mustard plan that copies the wheat plan (DAP plus urea) leaves the crop short of sulphur and costs oil yield.

Sulphur deficiency is widespread in Indian soils, especially sandy and light soils of Rajasthan, Haryana and Punjab, where most mustard is grown. Continuous use of DAP and urea, which contain no sulphur, has made this worse.

ICAR-DRMR, Bharatpur, reports that a basal dose of 40 kg sulphur per hectare through gypsum or elemental sulphur raises mustard seed oil content by up to 2% and seed yield by up to 25%, as listed on its technologies page. For a trader or oil mill, 2% more oil in the seed is a real price difference.

Sow irrigated mustard between 10 and 25 October, ideally finishing by 20 October, when day temperatures fall below about 32°C. Late sowing into November exposes the crop to aphid build-up and frost at flowering.

• Seed rate: 4 to 5 kg per hectare for line sowing (about 1.5 to 2 kg per acre). Broadcasting needs 5 to 6 kg per hectare.

• Spacing: about 45 cm between rows and 15 cm between plants for timely sowing; 30 cm between rows for late sowing.

• Depth: 2 to 3 cm. Mustard seed is small and will not emerge from deep sowing.

• Thinning: remove extra plants about 15 to 20 days after sowing to keep proper plant-to-plant distance.

Sowing dates in the north of the mustard belt (Punjab, Haryana) can run into early November for raya varieties, while eastern states often sow in mid-October on residual moisture.

Choose a variety released for your zone and your sowing and irrigation condition. ICAR-DRMR lists these recent Indian mustard varieties.

State universities also recommend their own varieties, such as RH 749 from Haryana. For dealers, stocking one timely and one late-sown variety per zone covers most farmer requests.

The ICAR recommendation for irrigated mustard is 80:40:40 kg N:P2O5:K2O per hectare plus 40 kg sulphur, 25 kg zinc sulphate and 10 kg borax per hectare where needed. Rainfed crops get a lower dose, all at sowing, as per your state recommendation.

Source for the doses: ICAR strategies and technologies for rapeseed-mustard. Per-acre figures are rounded from per-hectare values. Adjust all doses to your Soil Health Card.

There are two simple ways to meet the mustard dose per acre. The SSP route supplies sulphur with phosphorus; the DAP route needs a separate sulphur source.

Option A: SSP-based (recommended where SSP is available)

1. At sowing, apply 100 kg SSP (2 bags). This gives 16 kg P2O5 and about 11 kg sulphur.

2. Add about 6 kg bentonite sulphur (90% S) or about 40 kg agricultural gypsum to make up the remaining 5 kg sulphur.

3. Add 27 kg MOP for potash and 35 kg urea for the basal nitrogen.

4. At the first irrigation (30 to 45 DAS), broadcast another 35 kg urea.

Option B: DAP-based

1. At sowing, apply 35 kg DAP, 22 kg urea and 27 kg MOP.

2. Add 18 kg bentonite sulphur per acre, or 100 kg gypsum per acre as PAU suggests for sulphur-deficient soils.

3. At the first irrigation, broadcast 35 kg urea.

For farmers who prefer a ready basal mix, a mustard nutrition soil kit can be used along with the main NPK dose. Check the pack for what it contains so you do not double up on any nutrient.

Sulphur, zinc and boron each work at a different stage of the crop. Sulphur builds oil and protein, zinc supports early growth, and boron supports flowering and pod set.

• Sulphur: needed for oil synthesis and protein. Deficient plants show pale, cupped young leaves, purple tinge and poor pod filling. Gypsum is often the cheapest source; bentonite sulphur is more concentrated and easier to transport.

• Zinc: deficiency slows early growth on alkaline, sandy and high-phosphorus soils. Apply zinc sulphate at sowing if the card shows zinc below the critical limit.

• Boron: mustard is sensitive to boron shortage, which causes poor flowering, flower drop and empty pods. Apply borax at sowing on deficient soils, or spray a boron fertilizer at the label dose before flowering.

Do not overdo boron. The gap between enough and too much is narrow, so stick to the soil test and label dose.

Comparing sulphur sources for mustard

The right sulphur source depends on price, local availability and how much you need to carry to the field. Compare them on sulphur content, not bag price.

Check the sulphur percentage printed on the bag, since gypsum grades differ. Where the soil is also sodic (high pH), gypsum does two jobs at once.

Most nutrient problems in mustard show up between 30 and 60 days after sowing. Early diagnosis lets you correct them before flowering, when yield is decided.

Symptoms can overlap, so confirm with a soil or plant test when in doubt. A sulphur-deficient crop can look like a nitrogen-starved one, and adding more urea will not fix it.

Mustard needs few irrigations, but timing matters. The two critical stages are pre-flowering (35 to 45 days after sowing) and pod or siliqua formation.

ICAR advises avoiding irrigation between about 25 December and 15 January to reduce Sclerotinia stem rot, which spreads in cool, humid conditions around the crop canopy. Over-fertilizing with nitrogen also makes the canopy dense and invites aphids and stem rot.

For white rust and downy mildew, ICAR recommends metalaxyl seed treatment at 6 g per kg seed. A metalaxyl 35 WS seed treatment fungicide can be used as per the label. Trichoderma at 6 g per kg seed is advised for soil-borne diseases. Follow the product label and local agriculture officer advice.

For every 100 acres of irrigated mustard on the SSP route, plan about 200 bags of SSP (10 tonnes), around 54 bags of MOP, about 156 bags of 45 kg urea, and 150 to 200 kg of seed. Add bentonite sulphur or gypsum for the sulphur balance.

• Stock SSP early. It is the natural choice for oilseeds and moves quickly when DAP is scarce.

• Keep zinc sulphate and borax in smaller quantities and sell against soil test reports.

• Bundle seed treatment chemicals and bio-agents with seed sales, since most white rust control starts at the seed stage.

Bulk buyers can plan micronutrient and seed treatment supply with Katyayani Organics ahead of the October sowing window.

Pick a variety for your sowing date, test your soil for sulphur, zinc and boron, and plan your basal dose so that sulphur goes in at sowing. Sow by late October, give nitrogen in two splits, and irrigate at pre-flowering and pod formation. Follow the product label and local agriculture officer advice for all doses.