The basic fertilization must include phosphorus and potassium. Nitrogen should be distributed in part before transplanting, using forms of nitrogen with prolonged action (ammonia or slow release), especially in light soils, and the remaining part on the plant cover.
It is preferable that the transplant takes place in an already fertilized soil. If this is not possible, we can use a nutrient solution with 1-1.5 gr/liter of fertilizer. To prepare the solution we can choose a complete NPK fertilizer with a ratio close to 1-1-2 with the addition of calcium nitrate if necessary. If the transplant is done in a well enriched soil, fertigation will start starting from the third leaf.
With the fertilization on plant coverage the remaining part of nitrogen will be added, according to the vegetative development of the crop, the seasonal trend and the application technique, using quick-release fertilizer, such as calcium nitrate, ammonium nitrate and nitrate of potassium.
The distribution method is linked to the rate of absorption of the nutrient by the plant. Tomato is characterized by an almost parallel trend in the absorption of nitrogen and potassium with an absorption peak that normally falls between the fifth and ninth week of transplantation, in correspondence with the phase of rapid vegetative development and the beginning of flowering.
If you have a drip micro-irrigation system, (as is now common), fertigation can be applied. In this way it is possible to gradually distribute the fertilizers as the plants need them, automating the operation and simplifying the work.
Tomato is a plant with high water requirements, especially during the fruit enlargement phase.
Water requirements may vary according to the cultivation areas, the planting period, and the earliness of the crop. In general, close interventions are required, at least weekly, with watering volumes that are around 300-400 m3/ha /week. The first irrigation should be carried out when the residual water content in the first 40 cm of soil, measured by tensiometers, or estimated by means of a water balance, is approximately 50-60%.
It must be considered that among the most neglected aspects of irrigation management is undoubtedly the design of the irrigation and fertigation system. The adoption of unsuitable materials can make the effectiveness of the fertigation intervention almost null or cause significant damage to the crop or the environment.
The traditional perforated hose, for example, due to the known lack of homogeneity of water distribution, is not suitable for effective use for fertigation. The technique now offers new dripping hoses with flow rates and types of dripper labyrinth which, thanks also to a precise design and installation, allow a precise and regular distribution of water in the field, even in conditions of considerable length or terrain sloping.
The tomato plant can be considered on average tolerant to salinity, so waters with a modest / high saline content can be used.