Short term effects of synergistic inorganic and organic fertilization on soil properties and yield and quality of plum tomato

Tomato is one of the most important crops in the world and its cultivation is usually based on a great use of inorganic fertilizers applied as broadcast fertilization and with several fertigations. For a more sustainable agriculture authors studied the synergistic effects of the application of two different composts, combined with an inorganic fertilizer, on the main chemical-physical soil properties and on the yield and qualitative parameters of a plum tomato variety. Two composts, obtained mixing sewage sludge or the organic fraction of the municipal solid wastes with pruning residues, grape marc, and exhausted olive pomace, were tested at 2 or 4.5 t ha−1 in a field experiment, replacing a part of the inorganic fertilization and respecting the N crop requirement. From an environmental point of view, the addition of composts to the soil caused an increase in the total and available heavy metals content, even if no soil pollution has been recorded. The yield of tomatoes resulted higher with the combined application of amendments and inorganic fertilizer with respect to the sole inorganic fertilization. The quality of tomatoes was apparently not affected by the fertilization and, although certain heavy metals tend to increase their tomato concentration with the application of composts, their concentrations did not exceed the legal thresholds.