Agronomy Advice
May 17, 2024

Improve Potato Quality with Calcium

By: Natalie Wood

Did you know that up to 50% of wheat leaf samples show a deficiency in zinc, magnesium, copper and manganese?

Yara Agronomist and a Farmer in a potato field
Yara Agronomist and a Farmer in a potato field

Calcium is an important nutrient to a potato, it multitasks by supporting the maintenance of cell walls, healthy leaf growth and, most importantly of all, improved tuber development. With so much at stake, you can’t afford to ignore calcium availability.

Calcium deficiency causes what’s often referred to as ‘internal rust spot’ which is where cell wall weaknesses show up as small brown spots in the tuber. Essentially what’s happening is, as cells expand, they’re too weak to cope with the process and so collapse and necrosis occurs.

If potatoes are given a healthy dose of calcium as they grow, the nutrient is absorbed into the cell walls, strengthening them to prevent this internal rust spot. It also improves the strength of the potato skin, essential to create a good finish and protect the crop from damage as it’s harvested. In turn, with stronger potato skin and less damage, there’s also less opportunity for bacterial diseases to take hold.

Did you know?

Trials have consistently shown that applying sufficient calcium to growing potato crops you can expect to see:

  •  improved tuber skin finish by up to 70%
  •  reduced bruising by around 40%
  •  75% reduction of internal disorders such as internal rust spot

Apply the right calcium 

Getting the right source of calcium is important as if you’re going to the trouble and expense of spreading it, you want to be able to rely on the results. The source of calcium you need is calcium nitrate. Using calcium nitrate will ensure that the essential nutrient is available to your growing crops immediately.

There are some that believe that liming materials can provide enough calcium to make the difference to potato growth and quality, but this is not true. Liming materials contain calcium carbonate which is not water-soluble and so not freely available to your potato crop as it’s growing and when it needs it most.

Did you know?

99.5% of the calcium in the soil is unavailable to plants but 100% of calcium in YaraLiva Tropicote can be used by plants immediately.

Yara Recommendation

The best time to apply calcium to prevent internal rust spot is at tuber initiation, this ensures that as tubers are developing they have access to plenty of calcium to ensure strong and healthy growth.

You should have delivered 60-70% of the potato crop’s nitrogen requirement as a base dressing. This needs to be followed up with a top dressing of calcium and nitrogen at the tuber initiation stage. 

We would recommend 375-500 kg/ha of YaraLiva Tropicote which is a dense granular fertiliser and has hygroscopic properties meaning that it readily dissolves when in contact with the soil in humid conditions or a night dew, making the calcium immediately available to your growing tubers.