WORKSHOP ON IRRIGATION AND FERTIGATION OF PROCESSING TOMATO

A workshop on irrigation and fertigation of processing tomato was organized over two half-day session. The aim was to present recent results of research regarding irrigation which is a crucial component of processing tomato crop management and to approach subjects ranging from scientific knowledge to the tools available to enable growers to better control water supply. For I.S.H.S. it was the opportunity of bringing together two Working Groups of the Section Vegetables: the W.G. «Vegetables for Processing» and the W.G. «Water Supply and Irrigation».

Everything is important for the success of a tomato field according to given objectives: cultivar choice, crop protection, harvest conditions, etc. However the management of water supply is also determining factor mainly for harvest yield and quality. Indeed processing tomato is often cropped in areas with high water deficit during crop cycle and watering is generally necessary. Water management can be analysed from various viewpoints: in relation to fertilization and of course of pollution risks, in relation to use efficiency of this resource to be protected, in relation to its quality, etc.

Besides acquiring ever more precise knowledge, the researchers must also gather and apply this knowledge to the building of tools which would help farmers manage their crops and particularly irrigation, to aim at better pre-defined production objectives in advance and to obtain more regular and predictable results.

The first session of the workshop was devoted to «Irrigation systems and irrigation scheduling». It was introduced by Dr. C.J. Phene. The choice of the watering system (gravity, sprinkling or trickle) strongly governs the water use efficiency, with a known advantage to trickle. In the introductive conference the stress was particularly put on subsurface drip irrigation. This irrigation system was presented as the best solution for reducing water runoff, for reducing deep percolation below the root zone, for overcoming the infiltration variability of the soil surface and for optimizing irrigation scheduling.

The contributions dealt with the questions of evaluation of the crop water requirements, the influence of water regimes and water supply scheduling during cropping on the yield and on the main technological characteristics under various irrigation system. They provided various lightings from very different countries and cropping conditions. Presently the main targeted progress consists of the scheduling and the control of water management during the crop cycle (rate and frequency of watering according to the crop stages) to aim at given objectives of yield and quality production and reduce the pollution risks.

The second session was devoted to «Irrigation, fertigation, water quality and crop responses». It was introduced by Dr. A. Battilani and Prof. E. Fereres. The introductive conference dealt with prospects about decision support system for ferti-irrigation of processing tomato. Until now there have been few available models and no system capable of optimizing the supply of both water and nutrient for a given production aim. Such a system must be provided with data of small numbers and easy to pick up for farmers to adopt it.

The presentations have underlined various viewpoints. The type of plant material may influence the crop response to irrigation; then, all the cultivars must not systematically receive the same irrigation management. The relevance of associating fertilization management to irrigation management, in particular, fertilizer supply through drip irrigation (ferti-irrigation) helps increase efficiency and better adjust the amounts of supplied fertilizers to the crop uptakes; this contributes to reducing production costs.

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