Sulphur for Mustard: Dose per Acre, Best Source, Timing and How Much It Raises Seed Yield and Oil Content

Sulphur builds the oil and protein in mustard seed, and urea and DAP carry none. ICAR-DRMR Bharatpur lists a basal 40 kg S per hectare (about 16 kg per acre) as raising seed oil by up to 2 percent and seed yield by up to 25 percent. A 2023 DRMR trial found 60 kg S per hectare gave the best irrigated yield (2.71 t per ha). Punjab Agricultural University states no sulphur dose for mustard; it tells growers to take phosphorus from single superphosphate or, where that is not used, to add 80 kg gypsum or 13 kg bentonite sulphur per acre at sowing. In a rainfed IARI trial on a sulphur-short soil, 45 kg S per hectare lifted oil from 38.3 to 41.1 percent and seed yield by 28 percent, but each extra kilo of sulphur gave less than the one before. Apply it at sowing, test the soil first, and do not treat a fungicide sulphur as a nutrient source.

Mustard is an oil crop, and sulphur sits inside the machinery that builds the oil and the protein. It is part of the amino acids cysteine and methionine, of chlorophyll and of the glucosinolates that give mustard its bite. When sulphur runs short, flowering is delayed and prolonged, flowers are pale and pods are fewer and smaller.

The 2011 Indian Journal of Agricultural Sciences note by DRMR and Hisar authors puts it plainly: sulphur is now recognised as the fourth major nutrient after N, P and K, and takes part in making oil, sulphur amino acids, chlorophyll, vitamins and glucosinolates. The same note adds that oxidised sulphur compounds are needed to make sulpholipids and fatty acids, which are then built into the triglycerides that make up seed oil.

The Government of Saskatchewan makes a point that matters for timing: sulphur is not mobile in the plant, so a continuous supply is needed from emergence to crop maturity, and a shortage at any stage can reduce yield (Saskatchewan sulphur page). The page is written for canola, a related oilseed crop, so we use it only for this plant-behaviour point and for the symptom list.

If you want the whole crop plan around this one nutrient, read our mustard farming in India guide. This post stays with sulphur alone.

In a two-year IARI trial on a sandy loam in Delhi, a mustard crop took up 33.5 kg of sulphur per hectare with no sulphur applied and 45.4 kg with 45 kg S applied. The same crop took up about 79 to 105 kg N, 16 to 21 kg P and 71 to 91 kg K per hectare.

These are pooled figures for seed plus stalk from the IARI rainfed trial (Pusa Mustard 28, 2013-14 and 2014-15, yields 1.70 to 2.18 t per ha). The authors also worked out an apparent sulphur balance, meaning sulphur added minus sulphur taken up. With no sulphur applied the balance was minus 29.8 kg per hectare. At 45 kg S it was plus 3.4.

Source: IARI trial, Table 2, pooled over two years. Sulphur was applied as gypsum (13 percent S) at field preparation, with 80:40:30 kg N, P2O5 and K2O per hectare. The reading is simple. A crop that takes up 40 to 45 kg of sulphur and gets none back from the fertiliser bag is drawing down the soil. That is why a basal dose near 40 kg per hectare is the long-standing reference.

Why is the soil short in the first place? The IARI authors say sulphur deficiency occurs mainly through leaching, a shift towards sulphur-free fertilisers and the removal of more sulphur by high-yielding varieties. A national survey by ICAR-Indian Institute of Soil Science (Shukla et al. 2021) analysed 2,42,827 soil samples from 615 districts: 58.6 percent were short of available sulphur (acute deficient, deficient and latent deficient taken together), and in Rajasthan, Uttar Pradesh, Bihar, Gujarat and Madhya Pradesh, among other states, more than 60 percent of samples were.

The ICAR-DRMR reference is a basal 40 kg of sulphur per hectare, which is about 16 kg per acre. A 2023 DRMR irrigated trial suggests 60 kg per hectare (about 24 kg per acre). Punjab Agricultural University states no sulphur dose for mustard, only source quantities per acre. Your state package and soil test decide.

How to read the table. The 40 and 60 kg figures are research and institute numbers for a high-input crop. The PAU row is not a stated sulphur dose; it is a choice of sources and quantities. We converted the gypsum and bentonite quantities to sulphur using 13 percent S for agriculture-grade gypsum (the grade used in the IARI trial) and 90 percent S for bentonite sulphur (the grade PAU gives in its wheat section). PAU does not print the sulphur content of SSP, so we do not convert the 75 kg of SSP. Treat the 10 to 12 kg range as our reading, not as a PAU target.

None of these is a promise of what your field needs. They differ by soil, irrigation, yield target and state. Rainfed fields in a sulphur-short district will respond differently from a well-irrigated field with a sulphur-rich history. Start with a soil test (see the soil test section below) and your state university package, and use the figures here to judge whether your plan is far above or below the range researchers have tested.

In the IARI rainfed trial, every step of sulphur up to 45 kg per hectare raised yield, but the gain per kilo shrank each time. The first 15 kg added about 230 kg of seed per hectare, the next 15 kg added 150 kg and the last 15 kg added 100 kg. The profit still rose at 45 kg.

Source: Choudhary et al. 2021, pooled over two years, gypsum applied at field preparation. The authors report that the 45 kg and 30 kg treatments were statistically comparable for seed yield, and that partial factor productivity fell from 128.9 kg of seed per kg of sulphur at 15 kg to 48.6 kg at 45 kg. They say the extra sulphur did not bring a matching extra yield.

The 2023 ICAR-DRMR trial ran four sulphur levels (0, 20, 40 and 60 kg per ha) and five nitrogen levels in two seasons at Bharatpur. Seed yield was highest at 60 kg S (2.71 t per ha), and net returns and benefit-cost ratio were highest at 120 kg N plus 60 kg S. The abstract does not give yield at each sulphur level, so no step table is printed for that trial.

ICAR-DRMR lists a rise of up to 2 percent in seed oil from a basal 40 kg S per hectare. In the IARI trial oil went from 38.3 to 41.1 percent at 45 kg S, a gain of 2.8 points. How much you gain depends on how short your soil is and on the variety.

The table shows why a single headline number can mislead. The DRMR figure is a ceiling, the IARI figure comes from a soil its authors classed as deficient, and the Kota abstract gives an oil level with no comparison plot. Oil yield per hectare, which is oil percentage multiplied by seed yield, rises further than oil percentage because seed yield rises too: 653 to 898 kg per hectare in the IARI trial, which the authors report as 37.5 percent higher.

ICAR-DRMR gives up to 25 percent more seed yield from a basal 40 kg S per hectare. The IARI rainfed trial found 28.2 percent more at 45 kg S on a sulphur-short soil, and the Kota trial recorded 2.45 t per hectare at 40 kg S as bentonite sulphur. Your own gain depends on your soil.

If a trial or an advertisement quotes a very large gain, ask three questions: what was the sulphur level in the soil, how much was applied and in what form, and was the comparison a no-sulphur plot or a plot that already had a sulphur-containing fertiliser. A gain measured against a no-sulphur plot on a sulphur-poor soil will look bigger than one measured against a plot that already received some sulphur.

Light, sandy, low-organic-matter soils, fields under long rice-wheat or DAP-and-urea routines, and fields after heavy rain are the usual suspects. The IARI trial soil was a sandy loam low in organic carbon (4.5 g per kg) with 8.8 mg per kg available sulphur, which is below the 10 ppm line.

The IARI authors name three causes: leaching, a shift towards sulphur-free fertilisers, and more sulphur being removed by high-yielding varieties. The Government of Saskatchewan notes that sulphate-sulphur is very mobile in soil, like nitrate, which is why leaching is one of the causes.

• Sandy or light soils with low organic carbon. The responsive IARI soil was a sandy loam low in organic carbon.
• Fields where phosphorus has come only from DAP. DAP gives nitrogen and phosphorus and no sulphur, which is why PAU prefers SSP for mustard. Our post on SSP and other DAP alternatives covers the choice.
• Fields with a long run of high-yielding crops and no sulphur. The IARI sulphur balance showed a deficit of nearly 30 kg per hectare for an unfertilised mustard crop.
• Fields after heavy winter rain on light soil. PAU notes for wheat that sulphur deficiency is more severe when winter rains continue for long in early growth on sandy soils (PAU Rabi 2025-26). Our wheat yellowing post covers the same pattern.

Soil type alone does not decide it. Two neighbouring fields can differ. The soil test below is the only way to know.

Ask the lab for available sulphur. In the ICAR-IISS national soil survey, 7.5 mg per kg or less was graded acute deficient and above 7.5 up to 15 mg per kg deficient. Follow the range printed on your own report. The IARI trial soil, at 8.8 mg per kg, was called deficient by its authors.

The survey (Shukla et al. 2021) used six classes for available sulphur: acute deficient (7.5 mg per kg or less), deficient (above 7.5 to 15), latent deficient (above 15 to 22.5), marginally sufficient (above 22.5 to 30), adequate (above 30 to 40) and high (above 40). The IARI soil at 8.8 mg per kg falls in the deficient class and responded at every sulphur step up to 45 kg S per hectare.

Our guide to the soil health card explains how to read the sulphur line on your card. Check the unit and the range printed beside the value before you buy any sulphur source.

1. Sample the yellow or pale patch and a normal patch separately, same depth and same day.
2. Ask for available sulphur along with pH, EC and organic carbon.
3. Note the extraction method and unit printed on the report.
4. If sulphur is in your lab's deficient range, plan a basal sulphur dose from your state package. If it is marginal or adequate, ask your local agriculture officer whether a dose is worth the cost.

Soil pH matters too. A high-pH soil like the IARI field (pH 7.8) can still be sulphur-deficient, but pH changes how other nutrients behave, as our post on soil pH and nutrient lock explains.

Young top leaves turn pale or yellow and may cup upward, sometimes with a purple tinge. Plants are short or spindly, flowering is delayed and prolonged, flowers are pale, and pods are fewer and smaller. The Government of Saskatchewan lists these signs for canola, so confirm with a soil test.

The Saskatchewan government page sets the sulphur pattern against nitrogen: with a sulphur shortage the young top leaves turn yellow, while with a nitrogen shortage yellowing affects the older, lower leaves first. PAU describes the same split for wheat: sulphur symptoms start on the younger leaves, unlike nitrogen deficiency where yellowing starts on the lower leaves (PAU Rabi 2025-26). Both are for other crops, so use the leaf pattern as a pointer, not a diagnosis.

The table comes from the Saskatchewan page for canola. We found no ICAR or university leaf key written for mustard, so a soil test is the confirmation.

Our other posts cover the pests and diseases that mimic yellowing, such as mustard aphid attack. Check the underside of the leaf and the growing tip before you blame the soil.

In a Kota, Rajasthan trial at 40 kg S per hectare, bentonite sulphur at sowing and elemental sulphur were at par, and bentonite sulphur beat gypsum applied two weeks earlier on seed yield, net return and oil. PAU prefers SSP because it carries sulphur. Pick the source that delivers your target kilos of sulphur.

Here is what the Kota trial found (irrigated, clay loam, 80 kg N and 40 kg P2O5 per hectare, two seasons). Forty kg S as bentonite sulphur at sowing gave 2.45 t per ha with a benefit-cost ratio of 3 and was at par with elemental sulphur applied two weeks before sowing. Gypsum at the same 40 kg S, also applied two weeks before sowing, gave significantly less than bentonite sulphur on seed yield, net return and oil, and 12 kg S as bentonite sulphur was significantly lower too (Meena and Meena 2016). Production and economic efficiency per day were significantly higher than with no sulphur and at par for bentonite, elemental sulphur and gypsum. One trial on one soil does not make bentonite the best source everywhere.

The IARI authors describe gypsum as considered the cheapest source of sulphur and used it in their trial. PAU prefers SSP because it contains sulphur along with phosphorus.

On our catalogue, the ammonium sulphate fertilizer page lists 21 percent nitrogen and 24 percent sulphur, names mustard under oilseeds, and describes the product as 100 percent water-soluble. For a basal mustard dose, follow your state package for the rate, because the page gives general crop-group guidance.

Divide the sulphur you want by the sulphur percentage of the product. For 16 kg S per acre you need about 123 kg of gypsum at 13 percent, 67 kg of ammonium sulphate at 24 percent or 18 kg of bentonite sulphur at 90 percent. Check the printed grade on your bag.

All figures are our arithmetic from the grades in the earlier table, rounded, and ignore moisture and grade variation. PAU states no sulphur content for SSP, so SSP is left out of this table: read the grade printed on your bag and divide in the same way. PAU does name 80 kg gypsum or 13 kg bentonite sulphur per acre where SSP is not used; at the grades above these supply about 10 and 12 kg of sulphur, below the ICAR-DRMR 16 kg per acre reference. Which one suits your field is a question for your state package.

For the full per-acre bag plan with nitrogen, phosphorus and potash, use our mustard fertilizer schedule. It also compares SSP-based and DAP-based routes.

ICAR-DRMR lists sulphur as a basal dose, and PAU says to apply gypsum or bentonite sulphur at sowing when SSP is not the phosphorus source. In the Kota trial elemental sulphur and gypsum went in two weeks before sowing. We found no ICAR or university rate for correcting a standing mustard crop.

What the sources say, in order of trust: the DRMR technology is a basal dose of 40 kg S per hectare (ICAR-DRMR). PAU says to apply gypsum or bentonite-S at sowing for mustard (PAU Rabi 2025-26). In the IARI trial gypsum went in at field preparation. At Kota, elemental sulphur and gypsum went in two weeks before sowing and bentonite sulphur at sowing (Kota trial).

What about a standing crop? Two ideas turn up in search results: a foliar sulphur spray and a gypsum top dressing. The ICAR and university sources I opened give no foliar or top-dressing sulphur rate for mustard, so none is printed here. If the crop is already pale, ask your local agriculture officer which sulphur source and rate fits, and plan a basal dose from a soil test next season.

Sulphur and nitrogen work as a pair: the 2023 ICAR-DRMR trial found the best returns at 120 kg N plus 60 kg S per hectare. ICAR-DRMR also lists zinc and boron as separate gains on short soils. Sulphur does not replace them; use the soil test to decide which are really short.

Nitrogen. The DRMR 2023 trial tested sulphur at four levels against five nitrogen levels and found the highest net returns and benefit-cost ratio at the top of both, 120 kg N and 60 kg S per hectare. The IARI paper adds that the interaction between nitrogen and sulphur is generally positive in sulphur-deficient soil, and that plant nitrogen content rose with sulphur. A mustard crop that gets generous urea on a sulphur-short soil wastes part of it.

Zinc and boron. On the ICAR-DRMR technologies page, a basal 5 kg Zn per hectare lifted mustard seed yield by up to 12 percent, and 1 kg B per hectare basal (or two sprays of 0.25 percent boric acid at 40 and 60 days after sowing) by up to 21 percent. An integrated package of 2.5 t vermicompost or FYM, 80 kg N, 40 kg P2O5, 40 kg S, 5 kg Zn and 1 kg B per hectare beat the standard 80:40:0 by more than 10 percent. PAU recommends 10 kg zinc sulphate heptahydrate (21 percent) per acre only in soils testing low in zinc.

Use the soil test to decide whether zinc or boron is needed at all, and follow the label of any product you buy.

Variety, moisture, aphid attack, residue cover and how the oil is measured all change the number. In the IARI trial, zero tillage with 4 t per ha residue gave 40.5 percent oil against 39.0 percent under conventional tillage without residue. ICAR-DRMR reports aphid attack can cut oil content by up to 3.6 percent. Sulphur is one lever among several.

• Variety. ICAR-DRMR lists high-oil-content genetic stocks among the material it registered, so varieties differ. Check the variety first.
• Soil moisture and residue. The IARI trial ran on conserved soil moisture. Zero tillage with 4 t per ha residue gave 40.5 percent oil, significantly more than conventional tillage without residue and at par with the other treatments.
• Aphids. The DRMR page states mustard aphid reduced seed yield and oil content by up to 86.1 percent and 3.6 percent in Brassica juncea. Our mustard aphid control post covers thresholds and sprays.
• Measurement. DRMR standardised near-infrared (NIR) readings for oil in intact seed and compared Soxhlet, NMR and NIR methods, so the method behind a number matters.

If your oil is low and your leaves are pale on top, check sulphur first. If your oil is low and aphids were heavy, aphids may be the bigger cause. For the standard variety list, see the oil-content table in our mustard farming guide.

In the IARI rainfed trial the benefit-cost ratio rose from 1.32 with no sulphur to 1.89 at 45 kg S per hectare, with gypsum as the source. At Kota, 40 kg S as bentonite sulphur gave a benefit-cost ratio of 3. Compare your own source cost per kilo of sulphur.

The IARI authors say the extra income from 45 kg of sulphur exceeded its cost and that gypsum is considered the cheapest source. Their trial ran in 2013-15, so treat the ratios as direction, not current values.

Here is a simple way to compare sources on your own bill. Work out the sulphur per bag from the printed percentage, divide the bag cost by that sulphur, and add the cost of the other nutrient you also get, such as phosphorus from SSP or nitrogen from ammonium sulphate. A source that also replaces some phosphorus or nitrogen costs less per useful kilo. We do not print prices because they change each season.

Evidence for separate plans is thin. The IARI rainfed trial (sandy loam, rainfall of 128 and 242 mm in the two crop seasons) kept gaining up to 45 kg S, and the irrigated DRMR trial at Bharatpur was best at 60 kg S. Use your state package for your moisture situation.

In the IARI rainfed trial sulphur also raised water-use efficiency, from 9.7 kg seed per ha per mm with no sulphur to 12.3 with 45 kg (IARI 2021). Under irrigation, the 2023 DRMR trial points to 60 kg S with 120 kg N as the best-return combination at Bharatpur (DRMR 2023).

Salt-affected fields follow a different logic. Gypsum there is dosed to reclaim the soil, not to feed the crop, so see our posts on gypsum for saline and sodic soil and soil salinity. We found no ICAR or university sulphur dose for mustard on such soils to print here, so do not treat reclamation gypsum as your sulphur plan without doing the arithmetic.

The common ones are relying on DAP and urea alone, assuming a fungicide sulphur is a nutrient, copying one trial dose without a soil test, and chasing pale leaves with urea when the real gap is sulphur. Each is avoidable with a soil test and the right source.

• DAP plus urea and nothing else. Neither carries sulphur. Switch the phosphorus to SSP or add a sulphur source.
• Placing sulphur at the wrong time. In the Kota trial elemental sulphur and gypsum went in two weeks before sowing and bentonite sulphur at sowing; follow your state package for timing.
• Mixing up fungicide sulphur with fertiliser sulphur. Sulphur 80 percent WDG is sold as a fungicide for diseases such as powdery mildew, with crop-protection doses. Those are not the nutrient doses in this post.
• More urea for pale top leaves. Pale young leaves point to sulphur and pale older leaves to nitrogen (Saskatchewan government, for canola). Check the leaf pattern table above first.
• Skipping the soil test. The IARI soil that responded tested 8.8 mg per kg; your field may differ.
• Treating one trial as a rule. Doses of 40, 45 and 60 kg S per hectare appear in ICAR trials. Use the soil test and the state package to place yourself in that range.

Conclusion

Sulphur is a small input with a large effect on a mustard crop that is short of it. ICAR-DRMR reports up to 2 percent more oil and up to 25 percent more seed from a basal 40 kg per hectare, and the IARI and Kota trials show how that plays out in the field. Test the soil first. If the report shows sulphur in the deficient range, put a sulphur source in at sowing, count the kilos of actual sulphur and not the bags, and expect smaller gains as the dose rises. Where evidence is thin, such as foliar sprays and rescue of a standing crop, follow your state university and ask before you spend.