Micronutrient Management in Sugarcane: Zinc, Iron, Manganese, Boron, Copper and Sulphur, Symptoms, Doses, Timing and Ratoon Care

Zinc, sulphur, boron and iron are the gaps that matter most for Indian sugarcane. The ICAR national soil survey found 58.6 percent of Indian soils short in sulphur, 51.2 percent in zinc, 44.7 percent in boron and 19.2 percent in iron. PAU, tabulating AICRP (Sugarcane) advice, lists 25 kg ferrous sulphate and 20 kg zinc sulphate per hectare where deficiencies exist, with a 1 to 2 percent ferrous sulphate spray for iron chlorosis. TNAU gives 37.5 kg zinc sulphate and 100 kg ferrous sulphate per hectare for Tamil Nadu soils. These are two state packages. Test the soil first, check pH, and treat yellowing early, especially in ratoon cane.

It means finding out which of zinc, iron, manganese, copper, boron and molybdenum, plus sulphur, your cane field is short of, and correcting only those. PAU says a micronutrient shortage causes nutrient imbalance, reduced growth and lower sugar accumulation, so the loss shows up in tonnes and in sugar. A soil test decides the plan.

PAU's Indian Farming article calls sugarcane a nutrient-intensive crop and warns that continuous cultivation can deplete soil nutrients. It says iron and manganese support chlorophyll, while zinc contributes to enzyme function and photosynthesis. It also links good nutrient supply to better tillering, more millable canes and more biomass. See Verma and Singh, Indian Farming.

Most cane advice stops at nitrogen, phosphorus and potassium. This post covers the small-quantity nutrients only. For varieties, planting, NPK and pests, use our sugarcane farming guide, which is the hub. Here we go deeper on what to check in the soil, how to read the leaf, and what PAU, TNAU and ICAR trials say to apply.

A note on doses. Every dose in this post is printed with the institution that gave it, and each is that institution's own package, not a national rule. Where two sources differ, both are shown. Per-acre figures are our arithmetic (1 hectare = 2.47 acres). Spray strengths are in percent: 1 percent means 10 g in 1 litre of water.

Common. An ICAR AICRP study of 242,827 soil samples from 615 districts in 28 states found 58.6 percent of Indian soils short in sulphur, 51.2 percent in zinc, 44.7 percent in boron and 19.2 percent in iron. In Maharashtra, Karnataka, Uttar Pradesh, Bihar and Gujarat, more than half the sampled soils were short in both sulphur and zinc.

Source: Shukla et al. 2021, the ICAR All India Coordinated Research Project on Micro and Secondary Nutrients. Each state value is the sum of the acute, deficient and latent-deficient classes in the paper's state tables (our sums, rechecked against the tables on 12 Nov 2026). The samples came from all crops and fields, not only cane fields, taken from 0 to 15 cm in April to June, 2012 to 2018. Use the table to see which nutrient is likely short in your state, not to decide a dose.

The paper also counts districts. In 101 districts more than half the soils were short in sulphur, in 131 districts in zinc and in 86 districts in boron. For iron, copper and manganese, more than a quarter of soils were short in 83, 5 and 41 districts. So zinc, sulphur and boron are the widespread problems, while iron and manganese are more local, and copper is the rarest.

Shortages often come in pairs. The survey found sulphur and zinc short together in 9.30 percent of soils, zinc and boron in 8.70 percent, sulphur and boron in 7.00 percent, and zinc and iron in 5.80 percent. If one nutrient is short in your report, look closely at the next line.

Iron shows as yellow stripes or yellowing between the veins, running tip to base. Zinc gives pale yellow leaf blades, red lesions, fewer tillers and shorter internodes. Manganese gives pale uniform striping in the middle and tip of the leaf. Boron distorts young leaves. Copper gives a droopy top. Molybdenum streaks older leaves.

PAU and the SASRI sheet describe zinc a little differently, and both are given because field symptoms vary with variety and stage. SASRI is the South African Sugarcane Research Institute, a foreign institute. Its symptom sheet is used here only to describe what manganese, copper, molybdenum and boron look like, because the PAU article pictures only iron, zinc and boron. No SASRI dose is used anywhere in this post.

Treat a symptom as a reason to test, not as a final diagnosis. Several of these look alike, and nitrogen shortage also yellows cane. PAU describes nitrogen shortage as yellowing leaves with stunted growth, early leaf senescence and shorter stalks. Our posts on nitrogen deficiency and why plants grow slowly help you rule those out.

Look at where the yellow sits. Iron shortage shows as stripes between green veins, often over the whole leaf of young ratoon cane, in patches inside the field and mostly on soil above pH 8. Nitrogen shortage yellows the whole plant and stunts it. A patchy field on alkaline soil points to iron, then you confirm with a test.

SASRI adds that too much manganese can bring on iron shortage, so do not add manganese to a field only because the leaf is yellow. That warning comes from the symptom sheet of a foreign institute, so treat it as a caution, not a dose.

A practical way to walk the field: pick one yellow patch and one green patch of the same variety and age. Note the leaf position (young top leaves or older lower leaves), the soil colour, whether the patch follows a slope or an old channel, and the last irrigation date. Send soil from both patches to the lab, with the pH. If the two reports differ only in pH or one nutrient, you have your answer.

In practice a cane field often has more than one cause at once, which is why the sections ahead pair every symptom with a soil test.

PAU, tabulating AICRP (Sugarcane) advice, lists 20 kg zinc sulphate per hectare where zinc is short. TNAU, for Tamil Nadu, gives 37.5 kg per hectare basal on zinc-deficient soil, and a foliar spray of 0.5 percent zinc sulphate with 1 percent urea every 15 days until symptoms go. These are two state packages, not one national dose.

How to read this. A 0.5 percent spray is 5 g of zinc sulphate per litre of water, which is 1 kg in 200 litres (our arithmetic). The soil rates differ because the two institutions advise different soils and states. Follow the package of your own state or your sugar mill agronomist, and let the soil report decide whether you need the lower or the higher figure.

The TNAU page separates two situations. A zinc-deficient soil gets the basal dose. A standing crop already showing symptoms gets the foliar spray, repeated every 15 days until the symptoms disappear. That is useful because a late spray does not wait for the next planting. For the chemistry behind zinc lock-up in other crops, see our zinc deficiency in wheat post.

On high-pH, calcareous soil a foliar spray works better than soil iron. At ICAR-Sugarcane Breeding Institute, Coimbatore, a 2 percent ferrous sulphate foliar spray gave 92.24 t per hectare, on par with 150 or 225 kg per hectare to the soil. PAU lists 25 kg per hectare or a 1 to 2 percent spray.

Read the Coimbatore result carefully. Soil iron at 150 and 225 kg per hectare did raise soil and leaf iron, but the foliar spray was more effective in raising leaf iron and clearing chlorosis. The authors link the better foliar response partly to the higher calcium carbonate of the soil. On a soil like that, the spray reaches the leaf without passing through the lime.

Our arithmetic on the sources: the soil rates range from 25 kg (PAU) to 100 kg (TNAU) per hectare, which is about 10 to 40 kg per acre, and the spray strengths range from 0.5 to 2 percent. Do not average them. Pick the package that matches your state and soil, and check with your mill agronomist if the field is calcareous. For the pH side of the problem see soil pH and nutrient lock.

Yes. In the ICAR-SBI Coimbatore trial, six varieties responded differently to iron. Co 87025, Co 86010 and Co 8371 gained 26.87, 17.83 and 23.1 t per hectare from iron and were called susceptible. Co 86032, Co 8021 and Co 86249 gained only a little and were called tolerant to iron deficiency.

Source: Rakkiyappan, Thangavelu and Radhamani, Sugar Tech, ICAR-Sugarcane Breeding Institute (field experiment 1999 to 2000, abstract opened). The soil was sandy clay loam, deficient in iron but adequate in zinc, manganese and copper. This is one trial on one soil, and newer varieties are not in it, so use it as a pointer rather than a variety list.

What this means for you: if an alkaline, iron-short field is going to be planted, ask your mill or research station which varieties in your zone tolerate iron shortage. A variety choice can save sprays that a susceptible variety would need. If you already grow a susceptible variety, plan the foliar iron spray early rather than waiting for the whole field to turn pale.

These are needed in small amounts and shortages are less common. PAU lists 10 kg manganese sulphate, 10 kg copper sulphate and 2.5 kg sodium molybdate per hectare, only where deficiency exists. TNAU gives 5 kg copper sulphate per hectare, or a 0.2 percent copper sulphate spray twice during early growth.

The ICAR survey shows manganese is rarely short in cane states other than Punjab (55.3 percent), Tamil Nadu (27.0), Uttar Pradesh (26.1) and Bihar (23.6). Copper shortage is highest in Haryana, Punjab and Uttar Pradesh, at 28 to 31 percent. In most cane fields these three are the last to check, after zinc, sulphur, boron and iron.

The paper gives soil reasons too: manganese shortage goes with moisture deficit, low total manganese and coarse or calcareous soils, and copper shortage with calcareous, sandy soils and with eluviated soils rich in organic matter. If your field fits that picture and the leaf matches the symptom table, ask the lab to include manganese and copper in the test.

PAU lists 5 kg borax per hectare (about 2 kg per acre) where boron is short, and TNAU includes 5 kg borax in its 50 kg micronutrient mixture. Neither gives a boron-only foliar rate. The ICAR survey found boron short in 44.7 percent of Indian soils, so a soil test result matters more than a standard figure.

From the survey, boron is short in 72.0 percent of Maharashtra soils, 70.0 percent of Gujarat, 63.4 percent of Bihar and 57.4 percent of Karnataka, but only 9.1 percent in Haryana. A recipe copied from another state can be wrong for yours. The paper adds that lateritic and limed acidic soils, calcareous soils and leached sandy soils had the higher levels of boron deficiency, and it ascribes high deficiency in eastern India to alluvial and loess deposits and leaching in sandy-loam soils.

On the leaf, PAU describes boron shortage as distorted young leaves and death of the growing point. If you see that, test the soil for hot-water extractable boron, the method the survey used, and compare with the limits in the soil-test section below: 0.50 mg per kg or less is deficient or worse, and up to 0.70 is latent deficient.

We found no other Indian source we could open that gives a safe foliar boron rate for cane, so none is printed. Keep to the borax figure above or your state package, spread it evenly, and do not guess a higher dose because boron can burn crops when overdone.

PAU lists sulphur at 40 to 60 kg per hectare, with gypsum as an effective source. TNAU gives 500 kg gypsum per hectare on sulphur-deficient soil to increase cane yield and juice quality. The two figures use different units, one in kg of sulphur and one in kg of gypsum, so do not read them as the same dose.

Because the units differ, ask your fertiliser supplier or mill agronomist to convert the sulphur figure into the product you plan to buy, using the sulphur percent on its label. The same applies to ammonium sulphate or single super phosphate: they also carry sulphur, so check what your NPK plan already adds before buying more. Our gypsum guide covers the product itself.

The ICAR survey found sulphur short in 58.6 percent of Indian soils, with the highest shares in Gujarat (79.2 percent), Bihar (70.1), Maharashtra (65.9) and Karnataka (63.1). Tamil Nadu is lower at 29.8 percent. The authors say sulphur shortage is mainly due to variations in cultivation of sulphur-loving crops and less or no addition of sulphur-containing fertilisers.

PAU's table notes a growth benefit of sulphur in calcareous soils. If your soil is calcareous and the report shows sulphur at or below 22.5 mg per kg, sulphur belongs on your list along with zinc.

TNAU describes a 50 kg per hectare mixture: 20 kg ferrous sulphate, 10 kg manganese sulphate, 10 kg zinc sulphate, 5 kg copper sulphate and 5 kg borax, mixed with 100 kg of well-decomposed farmyard manure and applied to the soil before planting. It suits fields with several known shortages, not every field.

Source: TNAU. The page also offers an alternative, TNAU micronutrient mixture at 50 kg per hectare as enriched farmyard manure (EFYM), for higher cane yield. A blanket mix is a convenience, not a diagnosis. It adds copper and manganese to fields that may not need them, and the Indian survey suggests that for many states zinc, sulphur, boron and iron come first.

Compare the mixture with the single-nutrient rates earlier. It carries only 10 kg of zinc sulphate, far below the 37.5 kg TNAU gives for a zinc-deficient soil, and 20 kg of ferrous sulphate against the 100 kg TNAU gives for an iron-deficient soil. Use the mixture as a preventive base where the soil report is unclear, and the single-nutrient rate where a shortage is confirmed.

Put zinc, sulphur, boron and soil iron or the mixture in before or at planting. Use foliar sprays during tillering, when yellowing appears, and early in ratoon cane. PAU says nitrogen demand peaks 40 to 160 days after planting, so spraying then fits the labour already in the field. Re-test the soil every three to five years.

Nitrogen, phosphorus and potassium splits sit alongside this calendar and are in the sugarcane hub post.

Ratoon cane is where iron chlorosis often shows first. TNAU advises spraying ferrous sulphate at 2.5 kg per hectare on the 15th day after ratooning, and repeating twice more at 15-day intervals if the yellowing persists, with 2.5 kg urea added to the last spray. Its page gives the water volume nowhere, so confirm the tank mix with your agronomist.

The SASRI symptom sheet describes the typical ratoon picture: interveinal chlorosis of the whole leaf in young ratoon cane, patchy within the field, usually at soil pH above 8, sometimes spreading to the whole plant. That matches the PAU description of interveinal chlorosis from tip to base of the leaf.

The table follows the TNAU wording: spray on the 15th day, and if the chlorotic condition persists, repeat twice further at 15-day intervals. The dates 30 and 45 are our count from that rule.

Variety matters here too. The Coimbatore trial showed that tolerant varieties gained little from iron while susceptible ones gained 17 to 27 t per hectare. If the same patch yellows every ratoon, write the variety and the soil pH in your record, and test for iron and for free lime before the next cycle. Chlorosis that returns each year points to the soil, not to a missed spray.

Take a composite sample from 0 to 15 cm using an auger or spade, mix subsamples from the same uniform area, dry it in shade, and send it to a lab with a request for pH, organic carbon, sulphur, DTPA zinc, iron, manganese, copper and hot-water boron. Test yellow and healthy patches separately.

• Choose the area. One sample per uniform block of the same soil, variety and crop history. Do not mix a yellow patch with the green field.
• Number of subsamples. The ICAR survey took 3 to 4 subsamples for a holding under 1 ha, 6 to 7 for 1 to 3 ha and 9 to 10 for above 3 ha, then combined them into one composite sample. Use the same idea for each block.
• Depth and tool. The survey took 0 to 15 cm samples with a stainless-steel auger.
• Timing. The Soil Health Card programme says samples are generally taken after the rabi and kharif harvest or when there is no standing crop, so the report is ready before you plan the next planting.
• Preparation. The survey air-dried the samples, ground them and passed them through a 2 mm sieve before analysis. A lab does this for you; just send the sample dry and in a clean bag, labelled with field name and date.
• What to ask for. The Soil Health Card reports 12 parameters: N, P, K, S, Zn, Fe, Cu, Mn, boron, pH, EC and organic carbon, with fertiliser recommendations and amendments (PIB). The survey measured sulphur with calcium chloride extraction, zinc, iron, copper and manganese with DTPA, and boron with hot water.
• Standing crop with symptoms. Take soil from the root zone of a yellow patch and from a green patch, label both and send them together so the lab can compare.

When a lab test is not available, compare a yellow patch with a healthy patch in the same field, note the soil colour and pH if you have a meter, and ask the nearest KVK or the mill agronomist before spraying. Do not guess a micronutrient from a photograph. Our soil health card guide shows which lines of the card to read, and the official site is the Soil Health Card Portal, which PIB names.

Compare each line with the limits the ICAR survey used. Soil is called short in sulphur at 22.5 mg per kg or less, zinc at 0.90, boron at 0.70, iron at 6.5, copper at 0.60 and manganese at 5.0. Acute levels are far lower. Use the rating printed on your own report.

Source: Table 1 of Shukla et al. 2021, critical limits for Indian soils. The paper has six classes: acute deficient, deficient, latent deficient, marginally sufficient, adequate and high. The "short" column is the top of the latent-deficient class; the survey counted acute, deficient and latent classes together as deficiency. The authors advise re-testing at 3 to 5 year intervals because these nutrients change with soil and crop management.

One more point from the paper: farmers should add micronutrient fertilisers based on the deficiency level in the soil and the nature and demand of the crop, because crop responses differ with soil and crop. In plain terms, a report in the latent range is a reason to watch the crop, while a report in the acute range is a reason to act at planting.

Strongly. In alkaline and calcareous soil, iron and manganese become less available, and zinc, boron and copper shortages also go with high pH, lime and coarse texture. The ICAR paper names organic carbon, pH, clay content, CEC, biological activity and redox potential as the main drivers of micronutrient availability in soil.

The Coimbatore soil had pH 8.47 and 8.04 percent calcium carbonate and was short of iron. When a soil locks a nutrient, a larger soil dose does not always help. In that trial the foliar spray matched the largest soil doses and the authors tie that to the lime.

Our guides on soil pH and nutrient lock, soil salinity and types of soil in India explain these soil effects. A sodic or saline patch also yellows cane, and gypsum may be the first step there, not a micronutrient.

Use the soil route for planned, preventive doses at planting, and the foliar route for fixing symptoms on a standing crop. PAU and TNAU list both. We could not open any source that gives a micronutrient dose through drip fertigation in cane, so no drip dose is printed. Follow the product label for any soluble pack.

A foliar spray corrects the leaf, but it does not rebuild soil status. If the report shows zinc or sulphur at the acute level, the soil dose is still the base. For help choosing between soluble and granular products, read water-soluble versus granular fertiliser.

Seed cane is the same story. The sources we opened (PAU, TNAU, ICAR-SBI) put micronutrients in the soil or on the leaf and give no zinc or iron dip for setts, so none is printed here. TNAU's sett treatment is a biofertiliser slurry, which is a separate topic from micronutrients.

The common ones are applying a blanket mix without a soil test, copying another state's dose, treating a nitrogen problem as a micronutrient one, waiting too long to spray, and ignoring variety and soil pH. Each wastes money or leaves the real cause untouched, and each is avoided by testing first.

• No soil test. The survey shows boron is short in 72 percent of Maharashtra soils but 9 percent of Haryana soils. A recipe from another state can be wrong for yours.
• Copying a dose from the wrong state. PAU gives 25 kg ferrous sulphate and 20 kg zinc sulphate per hectare; TNAU gives 100 and 37.5. Both are right for their own states. Ask your mill or research station for the package of your zone.
• Heavy soil iron on lime-rich land. At Coimbatore, 2 percent foliar iron matched 150 and 225 kg per hectare to the soil.
• Confusing kg of sulphur with kg of gypsum. PAU states sulphur in kg; TNAU states gypsum in kg. They are different quantities.
• Using the mixture as a cure. The TNAU mixture has only 10 kg zinc sulphate, far below the 37.5 kg TNAU gives for a confirmed zinc-deficient soil.
• Waiting. TNAU's spray plan repeats every 15 days; the earlier you start in a ratoon crop, the more leaf area you save.
• Wrong diagnosis. Nitrogen shortage also yellows cane (PAU), so check the soil report before spraying.
• Ignoring variety. At Coimbatore, Co 87025, Co 86010 and Co 8371 were iron-susceptible and Co 86032, Co 8021 and Co 86249 were tolerant.

Always follow the product label for any pack you buy, and keep a record of dose, date and variety for each block.

Two combos and one collection on the site name sugarcane. The sugarcane growth combo pairs a gibberellic acid product with a six-nutrient chelated mix micronutrient, and the yield enhancer combo adds seaweed extract and NPK 00-52-34. The collection is titled for sugarcane yellowing leaves. Follow the label for use.

The sugarcane growth combo page says it contains Pro Grow (gibberellic acid 0.001 percent) and a Mix Micronutrient of zinc, iron, manganese, copper, boron and molybdenum, chelated with EDTA, for use during the growth stage of sugarcane. The sugarcane yield enhancer combo page lists seaweed extract, the same type of mix micronutrient, gibberellic acid and NPK 00-52-34, and says the mix corrects nutrient deficiencies in sugarcane plants.

The fertilizer for sugarcane yellowing leaves collection currently shows one product, a chelated six-nutrient micronutrient mix. A foliar chelated mix is a different tool from the soil-applied basal doses described above, and it does not replace them where the soil report confirms a shortage. This post prints no label dose; use the product label and your soil report.

Ask for the soil report, not the crop name, before suggesting a nutrient. Match the product to the confirmed shortage, quote PAU, TNAU or the state package for the dose, and use the survey table to explain why a neighbour's recipe may not suit this farmer's soil. Advise re-testing every three to five years.

• Zinc, sulphur, boron and iron first. These are the most often short, per the ICAR survey.
• Explain pH. If the soil is above 8, advice on foliar iron comes before advice on more soil iron.
• Know the pack. Work from the percent of the nutrient on the label, and convert kg of sulphur or zinc into kg of product before quoting a dose.
• Keep a field record. Note the variety, planting date, soil test, spray dates and dose. It makes next year's decision easier.
• Send odd cases to the research station or KVK. If symptoms fit no picture, an extension officer should look at the field.

Our soil health card guide helps a dealer read the card a farmer brings, and the sibling post on micronutrient management in onion (planned, not yet live) follows the same method for another crop.

Conclusion

Micronutrient management in sugarcane starts with the soil report and a look at the leaves. Check zinc, iron, sulphur and boron first, since the ICAR survey finds them short in the most soils. Fix pH and organic matter where you can, put basal doses in the furrow only for confirmed shortages, and use a foliar spray for iron chlorosis, especially in ratoon cane. Follow your state package for the rate, do not overdo iron, sulphur or boron, and re-test every few years.