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Ask Your Agronomist: Why calcium nitrate fertiliser is the best for tomatoes

Friday May 12 2017

Healthy tomatoes in a stand at a past Nakuru ASK Show.

Healthy tomatoes in a stand at a past Nakuru ASK Show. Calcium plays a very important role in maintaining the firm structure of cells of tomatoes during growth. PHOTO | FILE | NATION MEDIA GROUP 

Q: I am a farmer in Loitoktok, and I have a problem with my tomato fruits as they end up having a wet/burning appearance. I have been told its lack of calcium, how can I manage this problem?

The problem you refer to is a physiological disorder called Blossom end rot, and occurs in several other crops such as melons and capsicums, among others. Indeed, this is a problem resulting from a deficiency of calcium and boron (B).

The role of Calcium and B

Calcium plays a very important role in maintaining the firm structure of cells, and it is for this reason that its deficiency will make the cell walls weak and susceptible to collapsing and cracking, resulting in the typical physiological problems of fruit cracking and blossom end rot.

Boron, on the other hand, has a role to play in maintaining the flexibility of plant cells while allowing for their expansion. This ensures that the plants/fruits continue to expand in size without cracking.

Boron, therefore, plays a role in making the calcium even more efficient.

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The type of calcium you need

There are many sources of calcium, including common fertilisers like CAN and soil amendments such as lime and gypsum.

Calcium is predominantly taken up by the plants together with water and, therefore, its very important that the source used be one that provides soluble calcium, for it to be efficiently taken up.

However, the common sources of calcium mentioned above, CAN, lime and gypsum, provide calcium that is not readily soluble.

Therefore, its only available to the plants over a long period of time and in relatively small amounts.

Calcium Nitrate, on the other hand, provides soluble calcium, readily taken up by crops and, therefore, effective in helping prevent fruit cracking and blossom end rot.

To compare these products for example, it takes about one litre of water to dissolve 1kg of Calcium Nitrate, and you require about 415 litres of water to dissolve 1kg of gypsum and more than 60,000 litres of water to dissolve 1kg of lime.

Calcium Nitrate fertiliser such as NITRABOR will, therefore, help prevent fruit cracking and blossom end rot because it provides soluble calcium and boron for stronger cells in the tomato and other fruits.

For crop specific fertiliser recommendations, please consult the following agronomists in your area:

Western and Nyanza, Daniel Mui, 0702466343.

Rift Valley, Dennis Nyandaya, 0702466372.

Central, Robert Ngatia, 0702466318.

Vitalis Wafula, Yara East Africa Regional Agronomist