Understanding Tomato Crop Fertilization

Tomato yield and quality are determined by plant structure to prepare plant for heavy fruit load.  Leaf size, leaf balanced supply of nutrients at all stages while observing good color and number of shoots are critical to high yields. The leaf is agricultural practices. equivalent to a factory where food is manufactured and transported

Balanced fertilization is the supply of all nutrients required by the to fruits and other plant parts, therefore healthy leaves is like well crop at the right quantities and ratios in all stages of crop growth serviced factory whose production efficiency is optimal. The capacity and development. of the factory “LEAF” is reduced by small size, dead spots, yellowing, and drying of leaf margins. This will translate to low yields. Key nutrients needed are nitrogen, phosphorus, potassium, magnesium, sulfur, boron, zinc, manganese and molybdenum.

Flowering and Fruit set: Good flowers appear bright yellow in color and open fully while poor ones tend to be pale and half open with high tendency to shade prematurely thus lowering yields. Good flowering will result in uniform fruit set. Nitrogen and magnesium are needed for photosynthesis and maintenance of plant health. Phosphorus provides energy required for flowering, pollination and fruit setting. Zinc and Potassium are needed to boost flowering and early fruit development, and calcium to prevent early fruit drop while boron is required for proper pollination. Lack of balanced fertilizer will cause flower abortion, poor pollination, early fruit drop and yellowing of the plants.

Fruit development and ripening: Sustained supply of balanced fertilizers is important to maintain and expand developing fruits.

Tomato growing challenges                                                                      Potassium and calcium are specifically important in quality.

Importance of potassium in quality

•   Improved skin finish and uniform ripening

•   Improved sweet taste

•   Tolerance to drought and cold stress

Importance of calcium in quality

Imbalanced fertilization results into poor root formation, weak plants, poor flower • Reduced incidences of Blossom End Rot formation, poor fruit set, and poor quality fruits such as uneven ripening and

• Extended tomato shelf life                                                                                                                              • Resistance to transport and handling bruising

• Reduced rotting in the field and during transportation

In addition, phosphorus is important for continued flowering and seed development which enhances fruit size. However, phosphorus is easily fixed in acidic soils and becomes unavailable to plants. It is required in all stages of growth up to fruit development and not just important in the early stages. Ensuring sufficiency up to the fruiting stage will have a positive impact on the yield. Calcium improves strong plants, good flower formation, uniform fruit setting, and high yields of good tolerance to insects and diseases resulting in cost savings on chemicals sprays.

Challenges in tomato growing include;

1. Limited knowledge on tomato fertilizer requirements; low In summary ^{inputs usage,} Each nutrient has its own specific role in plant development and cannot be replaced by another thus the concept of balanced

2. Blossom end rot; resulting to more than 30% loss of marketable fertilization.

yields.

3. Fruit quality; small fruits, uneven ripening, poor skin finish, soft At Yara, we have developed a balanced fertilizer program for tomatoes fruits, and poor keeping quality. taking into account plant nutrient requirements at each stage as well 4. Flower abortion; low conversion rate of flowers to fruits during as soil conditions. The Yara recommended fertilizer program is giving farmers high yields, fruit quality and higher profits.

5. Poor rooting system

6. Pest management

Root Establishment: Availability of key nutrients at the early stages is important for optimal rooting (increasing share of root hair volume). Apart from phosphorus other nutrients are also required for proper root formation. For example, nitrogen and potassium and in particular calcium, boron and zinc are vital for the formation of root tips from where most of water and nutrients are absorbed.

Regional Agronomist East Africa