Potato Nutrient Deficiency: Signs, Causes and the Fertilizer That Fixes It
Potato nutrient deficiency is one of the first things to check when the leaves of your patatas (potato) turn yellow, purple or burnt at the edges. On Philippine farms the usual ones are nitrogen, potassium, phosphorus, magnesium, calcium, boron, sulfur and zinc. This guide shows where each one starts, how to be sure, and the fertilizer that fixes it.
Start with one question: did the change begin on the old leaves or on the young ones? Nitrogen, potassium, phosphorus and magnesium move inside the plant, so a shortage shows on the old, lower leaves first. But calcium, boron, sulfur and zinc stay where the plant first put them, so the young leaves and the growing tip show it first. After that, the color and the pattern narrow down which potato nutrient deficiency you have, and a soil test confirms it. Each one below has its signs, its causes and its fix.
Potato nutrient deficiency signs, old leaves and young leaves
Shows first on the old leaves
| Nutrient | Where it starts | What you see | Fix with |
|---|---|---|---|
| Nitrogen | old, lower leaves, the whole plant | Whole leaves, veins included, turn evenly pale yellow, starting low on the plant. | Urea 46 0 0, Ammonium sulfate 21 0 0 |
| Potassium | old, lower leaves, leaf edges and tips | Leaflets crinkle, tips burn and dead patches form between green veins, turning the leaf scorched and dark. | Muriate of potash 0 0 60, Sulfate of potash 0 0 50 |
| Phosphorus | old, lower leaves, the whole plant | Short, dark plants with purple stems and leaf undersides, and leaflets curled upward. | Single superphosphate 0 20 0, Complete 14 14 14 |
| Magnesium | old, lower leaves, between the veins | Mottled yellow between the veins of young mature leaves, then dead scorched patches. | Epsom salt / magnesium sulfate, Dolomite |
Shows first on the young leaves
| Nutrient | Where it starts | What you see | Fix with |
|---|---|---|---|
| Calcium | young leaves and the tip, fruit, grain or tubers | Young leaves small, pale and curled, sprout tips black, and rusty spots inside the tubers. | Agricultural lime, Dolomite |
| Boron | young leaves and the tip | The growing tip dies and the plant turns bushy. Young leaves wilt even with enough water. | Borax |
| Sulfur | the whole plant, young leaves and the tip | The whole plant, young leaves included, yellows evenly, with reddish veins and leaf stalks. | Ammonium sulfate 21 0 0, Single superphosphate 0 20 0 |
| Zinc | young leaves and the tip, between the veins | Young leaves yellow and mature leaves get pitted, dead spots between green veins. | Zinc sulfate, Agricultural lime |
Before you buy fertilizer for a potato nutrient deficiency
So use the table to pick the likeliest potato nutrient deficiency, then read its section below. Also keep in mind that dry soil, standing water, cold nights, a pest or a disease can look the same. That is why it pays to check the roots and the whole field first.
Nitrogen deficiency in potato
Leaves turn evenly yellow, veins and all, starting on the older leaves. When nitrogen is given, young leaves green up but the old ones stay yellow. Severe shortage makes leaves cup upward, and the crop stops early with small tubers. You see it most at this stage: before and during tuber set.
Why nitrogen deficiency happens in patatas
Sandy soils, heavy rain that washes nitrogen out, and too little fertilizer in highland fields cropped every season.
How to tell it apart
Sulfur deficiency also yellows the whole plant but includes the young leaves and gives a reddish tint to veins. Magnesium deficiency yellows between green veins. To be sure, check that the yellowing started on the old leaves, then test the soil. A leaf tissue test confirms it.
What to apply for nitrogen deficiency
Apply Urea 46 0 0 or Ammonium sulfate 21 0 0 following the soil test, hilled in beside the rows. Give a urea spray of 10 g per liter (160 g in a 16 liter sprayer) every 15 days for quick help. A usual side dress is 1 to 2 bags of Urea 46 0 0 or 2 to 4 bags of Ammonium sulfate 21 0 0 per hectare, 30 to 45 days after planting.
- Urea 46 0 0
- Ammonium sulfate 21 0 0
- Complete 14 14 14
Sold here with nitrogen: Atlas Granular Urea (46 0 0) by Atlas Fertilizer, Amigo Planters Ammonium Chloride by La Filipina (25 0 0), Agripower 46 0 0 (Locally Blended) Coated by Green Acres Agri Tech and Calcipro by Ramgo (15.5 0 0 with 18.8 percent calcium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to urea fertilizer, and the page on nitrogen deficiency in every crop. In anee.io, Anee, the smart farm technician, reads a photo of the leaf and tells you which nutrient is short.
To keep it away, split nitrogen between planting and hilling, and add compost.
Potassium deficiency in potato
Leaflets crinkle, the tips burn and dead tissue spreads between the veins while the veins stay green. Leaves curl and look scorched, with dark edges. The yellowing does not reverse even after potash is given, and tubers stay small. You see it most at this stage: tuber bulking.
Why potassium deficiency happens in patatas
Sandy and acid soils, and fields cropped for years without potash. Potato needs a higher soil potassium level than most field crops.
How to tell it apart
Magnesium deficiency can look much the same when advanced, but starts as mottled yellow between veins. Early blight gives round spots with rings. To be sure, soil test for potassium (aim higher than for field crops) and a leaf test.
What to apply for potassium deficiency
Apply Muriate of potash 0 0 60 following the soil test, split between planting and hilling. For quick help spray potassium sulfate at 10 g per liter (160 g in a 16 liter sprayer) in the morning. A usual dose is 2 to 3 bags of Muriate of potash 0 0 60 per hectare, half at planting and half when the roots or tubers start to swell.
- Muriate of potash 0 0 60
- Sulfate of potash 0 0 50
- Complete 14 14 14
Sold here with potassium: Atlas Muriate of Potash (MOP) by Atlas Fertilizer (0 0 60), Simplot Sulfate 0 0 50 by Nutranta, Potassium Nitrate by Parafield (13 0 46) and Qrop Mix Production 14 0 23 plus 13 Cao by Farmtech Agriland (14 0 23 with 9.3 percent calcium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to potash fertilizer, and the page on potassium deficiency in every crop.
To keep it away, keep the soil pH above 6 with lime or dolomite, add organic matter and wood ash, and give potash every crop.
Phosphorus deficiency in potato
Plants grow slowly and stay stunted and darker than normal. Stems, leaf stalks and the undersides of leaves turn purple, and the lower leaf surface looks grey green. Older leaves get dead spots and leaflets curl upward. You see it most at this stage: early growth.
Why phosphorus deficiency happens in patatas
Acid and volcanic soils that lock up phosphorus, and cold soil early in the season.
How to tell it apart
Potassium deficiency also curls leaflets but burns the tips and edges. Purple top viruses give purple and rolled top leaves, not dark plants. To be sure, soil test for available phosphorus (potato needs a higher level than field crops).
What to apply for phosphorus deficiency
Use single superphosphate for a quick fix and bone meal or rock phosphate for the long term, following the soil test. Phosphorus is taken up best at pH 6.2 to 7.0. Band it near the seed pieces at planting. A usual basal dose is 4 to 6 bags of Complete 14 14 14 per hectare in the furrow at planting.
- Single superphosphate 0 20 0
- Complete 14 14 14
- 16 20 0
Sold here with phosphorus: Philphos 18 46 0 (Di Ammonium Phosphate), Atlas Super Gro (16 20 0) by Atlas Fertilizer, Amigo Planters Granular Single Super Phosphate by La Filipina (0 18 0 with 11 percent sulfur) and Triple Super Phosphate by Newman Chemicals (0 46 0). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to 16 20 0 fertilizer, and the page on phosphorus deficiency in every crop.
To keep it away, apply phosphorus at planting each crop and lime acid soils.
Magnesium deficiency in potato
Mottled yellow areas form between the veins, first on young mature leaves. In advanced cases dead tissue between the veins gives a scorched look that can resemble potassium deficiency. You see it most at this stage: mid season.
Why magnesium deficiency happens in patatas
Acid, sandy soils in rainy highlands, and heavy potash.
How to tell it apart
Potassium deficiency starts with burned tips and crinkled leaflets. To be sure, soil test for magnesium and pH, and a leaf test.
What to apply for magnesium deficiency
Give about 80 kg magnesium sulfate per hectare in bands near the plants. Apply it apart from potash. Use Dolomite on acid soils over the long run. Put the soil dose in before planting or when the rains begin. Sprays show results in 10 to 14 days.
- Epsom salt / magnesium sulfate
- Dolomite
Sold here with magnesium: Dolomite by A6 Agrisource (24 percent calcium and 11 percent magnesium), Agsmart Kieserite Granule (20 percent sulfur and 16.3 percent magnesium), DDDD Planter's Choice Magnesium Sulphate Monohydrate by Modern Time (15.1 percent magnesium) and Zetryl MAG 9 by Zetryl Chem (9 percent magnesium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to complete fertilizer, and the page on magnesium deficiency in every crop.
To keep it away, lime acid fields with dolomite instead of plain lime. Test the soil every two or three years.
Calcium deficiency in potato
Young leaves and leaflet tips turn pale, stay small and curl slightly. Severe cases stunt the plant. Sprout tips can turn black and die, and tubers show rusty brown spots inside. You see it most at this stage: tuber bulking, and in stored seed potatoes as they sprout.
Why calcium deficiency happens in patatas
Very acid soils, and also higher pH sandy soils, where potatoes may respond well to added calcium. High phosphorus and boron shortage make it worse. Heavy potash or ammonium fertilizer, salty soil and dry spells keep calcium from reaching fruit and young leaves.
How to tell it apart
Boron deficiency also kills the growing point and gives brittle leaves. A leaf test does not show tuber calcium, since calcium may reach the leaves but not the tubers. To be sure, soil pH and calcium test. Cut tubers to look for internal spots. A soil test for calcium and pH, and a leaf test, confirm it.
What to apply for calcium deficiency
On acid soils, lime about 250 kg per hectare where the pH is 5.5 to 6. About 840 kg per hectare in two splits where it is 3.5 to 4.5. On alkaline soils, or to add calcium without raising pH, use Gypsum.
- Agricultural lime
- Dolomite
- Gypsum
- Calcium nitrate
Sold here with calcium: Planters Products Lifelime (36.2 percent calcium), Dolomite by A6 Agrisource (24 percent calcium and 11 percent magnesium), Calcipro by Ramgo (15.5 0 0 with 18.8 percent calcium) and Philphos Gypsum (22.2 percent calcium and 17.4 percent sulfur). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to fertilizer for tomatoes, and the page on calcium deficiency in every crop.
To keep it away, test the soil before each crop and keep the soil evenly moist so calcium can move into the tubers. Keep potash in balance with magnesium and calcium.
Boron deficiency in potato
Leaves pale slightly. The growing tip dies, so the plant loses its main shoot and grows in a bushy rosette. Leaves turn brittle and break easily, and young leaves droop even though the soil is still wet. You see it most at this stage: mid season.
Why boron deficiency happens in patatas
Sandy soils low in organic matter, high pH soils and dry spells.
How to tell it apart
Calcium deficiency looks very similar. A soil or leaf test separates them. To be sure, soil test for boron. In a soil test, less than 0.5 ppm of boron is low.
What to apply for boron deficiency
Give about 10 kg Borax per hectare to the soil, or a borax spray of 1 g per liter (16 g in a 16 liter sprayer). Keep boron apart from calcium and ammonium fertilizers. Give boron before flowering: flowers and fruit set need it most.
- Borax
Sold here with boron: Etifert 11 (Borax Decahydrate) by Zetryl Chem (11 percent boron), Fertibagra 15G by Unilox Far East Resources (14.6 percent boron), B17 (Boric Acid) by Newman Chemicals (17 percent boron) and Better Yield by Bacphil Planters Fertilizer (0 0 0.9 with 10 percent boron). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to foliar fertilizer, and the page on boron deficiency in every crop.
To keep it away, test for boron before planting on sandy fields. Test the soil every two or three years. Keep organic matter up with compost, manure or crop residues.
Sulfur deficiency in potato
The whole plant yellows evenly, young leaves included, with a reddish tint in the veins, leaf stalks and leaf undersides. In advanced cases leaves stand upright, twist and turn brittle. You see it most at this stage: early to mid growth.
Why sulfur deficiency happens in patatas
Soils low in organic matter, sulfur free fertilizer for years, and burning crop waste.
How to tell it apart
Nitrogen deficiency starts on the old leaves and has no red veins. To be sure, soil and leaf test for sulfur. In a soil test, less than 10 ppm of sulfate sulfur is low.
What to apply for sulfur deficiency
Use a sulfur bearing fertilizer such as Ammonium sulfate 21 0 0 or single superphosphate. Give about 25 kg sulfur dust per hectare on sulfur poor soils, or Gypsum on alkaline soils. Give it at planting or with the first side dress.
- Ammonium sulfate 21 0 0
- Single superphosphate 0 20 0
- Gypsum
Sold here with sulfur: Atlas Ammosul 21 0 0 by Atlas Fertilizer (21 0 0 with 24 percent sulfur), Philphos Gypsum (22.2 percent calcium and 17.4 percent sulfur), Harvester Sulphate of Potash by Universal Harvester (0 0 50 with 17.5 percent sulfur) and Agsmart Kieserite Granule (20 percent sulfur and 16.3 percent magnesium). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to ammonium sulfate fertilizer, and the page on sulfur deficiency in every crop.
To keep it away, add organic matter and use a fertilizer that carries sulfur. Test the soil every two or three years.
Zinc deficiency in potato
Young leaves yellow and mature leaves show small pits on the upper surface between the veins. Dead patches between the veins spread while the main veins stay green. You see it most at this stage: early to mid growth.
Why zinc deficiency happens in patatas
High pH soils, heavy phosphorus, and soils low in zinc. Potato has a medium zinc need.
How to tell it apart
Magnesium deficiency yellows between veins on older leaves without pitting. To be sure, soil and leaf test for zinc. In a soil test, less than 0.8 ppm of zinc is low.
What to apply for zinc deficiency
Give about 20 kg Zinc sulfate per hectare to the soil, or in severe cases a morning spray of 2 g zinc sulfate with 2.5 g lime per liter. Keep zinc and phosphate applications apart. Give the soil dose at planting or when the rains begin, and sprays on young growth.
- Zinc sulfate
- Agricultural lime
Sold here with zinc: Harvester Zinc Sulphate Heptahydrate by Universal Harvester (22 percent zinc), Petbowe Zinc Sulphate Monohydrate (33 percent zinc), Tierramino ZN by Unilox Far East Resources (7 0 0 with 10 percent zinc) and Liquid Chelate Zinc with Sulfur by Sagrex (10 percent zinc and 5 percent sulfur). Check the FPA registration on the bag and follow the label rate. For the how and when, see our guide to fertilizer with zinc, and the page on zinc deficiency in every crop.
To keep it away, keep soil pH between 5 and 7.5 and test for zinc. Test the soil every two or three years.
A soil test is the surest check for any potato nutrient deficiency. Before you buy, ask your Municipal Agriculture Office where to send a soil sample. The DA regional soil laboratories test soil, and the result says how much of each fertilizer your patatas needs. That saves money, because extra fertilizer is money lost.
Open the Nutrient Deficiency Finder, pick patatas, say where the leaves changed first and what you see, and get the fertilizers sold here that fix it.
- Anee, the smart farm technician, reads a photo of the leaf
- The cropping calendar dates every fertilizer application of your season
Potato nutrient deficiency questions
Why are my patatas leaves turning yellow?
What fertilizer fixes nitrogen deficiency in potato?
What fertilizer fixes potassium deficiency in potato?
What fertilizer fixes phosphorus deficiency in potato?
How do I know which nutrient my patatas lacks?
Find the missing nutrient and fix it
With Libre + Anee, read the whole guide: how to tell the deficiency from look alikes, how to be sure, what to apply, and the fertilizers sold here that supply it.
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