Precision fertilisation in vegetable and ornamental crops

Daniele Massa [Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria (CREA) - Unità di ricerca per il vivaismo e la gestione del verde ambientale ed ornamentale, Pescia (PT)];
Luca Incrocci, Alberto Pardossi [Dipartimento di Scienze Agrarie, Alimentari e Agro-ambientali, Università di Pisa]

Vegetable and ornamental crops are highly intensive cropping systems based on a large application of agro-chemicals (plant protection products and fertilisers), which often determine a strong environmental impact. On the other hand, these cropping systems can be quite profitable as they employ new technologies and approaches to optimize the fertilisation and the management of pests and diseases. As far as fertilisation is concerned, some of these techniques have been validated under different conditions and could be applied to most commercial farms while others techniques are still under development. In brief, sustainable fertilisation consists in supplying the appropriate fertiliser rate based on crop mineral requirement and the actual nutrient availability in the root zone.
Sustainable fertilization can be achieved either using a prescriptive or a corrective method. In the former case, the amount of fertilizers required by the crop is estimated using a nutrient mass balance. In the corrective method, fertilization is aimed at maintaining an adequate nutrient concentration at the root zone level. In both cases a check-up of the nutrient availability along the crop cycle is necessary. The “speaking soil” and the “speaking plant” approaches can be used to optimize fertilization practices. In the “speaking soil” approach, the supply of fertilisers is calculated to maintain a target nutrient concentration in the root zone, which is generally determined through the analysis of soil extracts. The application of this approach is quite easy in soilless substrate cultures systems where drainage water and/or substrate samples can be easily collected and analyzed. The “speaking plant” approach can be adopted for monitoring nutrient status in some parts of the plant (leaf lamina or petiole) or on the whole canopy using either destructive (leaf sampling followed by laboratory analyses) or non destructive methods (canopy reflectance, chlorophyll fluorescence, leaf transmittance). Simulation models can be integrated in decision support system for fertilisation. Finally, the use of controlled release fertilizers can significantly increase the nutrient use efficiency, especially in substrate cultivations.

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