Tomato - nutritional summary

Peak requirement is just before flowering. Most Phosphorus is required early on in the plant’s development to ensure good root growth and flowering. Potassium is needed in greater quantities than nitrogen. Calcium is also needed in relatively large quantities. In many situations, it is equally as important as nitrogen. Over 60% of nitrogen, phosphorus and potassium taken up by the plant, is utilized by the fruit.

While most phosphorus is required early on, nitrogen's peak requirement is just before flowering. Most calcium needs are from flowering through fruit development and up to harvest.

More potassium, nitrogen and calcium are removed by tomatoes than any other nutrient. The image above refers to processing tomatoes in Greece (yield 121t/ha).

Nitrogen

Excessive use of nitrogen can produce a crop that is too vigorous, has poor flowering and excessively large fruit. Around 2.2 – 2.4kg of nitrogen is removed for every tonne of crop produced. Some nitrogen is normally broadcast preplanting or at transplanting, unless rainfall patterns are likely to lead to leaching. This is followed by side dressing prior to flowering.

Calcium

Calcium needs are around 1.7 kg Ca/t of fruit. In many situations, it is equally as important as nitrogen. Peak calcium needs are from flowering, through fruit development and up to harvest. Since only 5% of Ca is found in fruit and 95% in the vegetative parts of the plant, the need for Ca is also high during vegetative growth. Therefore a steady supply of calcium is needed throughout the season.

Potassium

Potassium is needed in greater quantities than nitrogen. Plant uptake is around 2.6-3.6kg K/t of fruit with the highest demand during fruit bulking. Base applications of potassium are usually followed by regular applications throughout the season.

Magnesium

Magnesium is also important, though it is needed at lower rates than calcium – crops require 0.3-0.6kg Mg/t of fruit – split throughout the season. Peak uptake is around flowering.

Phosphate

Most Phosphorus is required early on in the plant’s development to ensure good root growth and flowering. Crops need 0.2 – 0.4kg P/t of fruit.

Sulfur

Sulfur is needed throughout the growing period with tomato plants taking up around 0.6kg S/t of fruit produced.

Micronutrients

While much lower levels of micronutrients are needed to satisfy yield and quality tomato crop production, the correct balance of these trace elements is essential. Leaf tissue analysis to assess micronutrient need, will enable deficiencies to be correctly diagnosed and treated.

The key micronutrients are boron, which has a significant effect on fruit ripening characteristics, and zinc. See the micronutrient removal in fruit table above (mg/Kg as dry weight).

Boron

Boron is one of the key micronutrients. It has a significant effect on fruit ripening characteristics. It is essential for the structural integrity of the plant and important for pollen viability, flower and fruit development.

Zinc

Zin is another key micronutrient. It is important for the development and function of growth regulators (e.g. auxin) that influence internode elongation.