For optimal nitrogen (N) fertilization management in processing tomatoes, Nitrogen Enhanced-Efficiency Fertilizers (N-EEFs) can help regulate N availability in the soil, synchronize it with plant demand, and reduce the risk of N leaching. Within the Agritech project Task 3.2.2, two N-EEFs with different modes of action were selected to determine their effect on processing tomato growth, yield, and quality, as well as on N-leaching risks. These N-EEFs were AGROCOTE 44 2-3m (44% N, controlled release) and NUTRITEC 46 (46% N, with nitrification inhibitor).
Processing tomato (cv. HEINZ 5108) was transplanted on May 25, 2024, and four treatments were compared using a complete-block design with three replicates: the two abovementioned N-EEFs together with two controls, i.e., an unfertilized control and a control fertilized with urea. All fertilizers were broadcast at transplanting at a dose of 200 kg N ha-1. Growth analyses were performed by sampling plants every 10–14 days from about 1 month after transplanting until the final harvest. N crop status was monitored at each sampling by a chlorophyll meter (SPAD-502, Minolta), sap nitrate meter (LAQUAtwin, Horiba), and a portable multispectral radiometer (Rapidscan CS-45). Plots were equipped with suction cup lysimeters to monitor the N leaching risk at 0.6 m depth.
Preliminary results suggest that N-crop status, plant growth, and yield were similar in the different fertilized treatments. On average, the aboveground biomass of fertilized treatments was approximately 8.5 t ha−1 (dry weight), while the marketable fruit yield was 58 t ha−1 (fresh weight). For fruit quality parameters, no significant differences were observed among treatments, although °Brix from EEF treatments was generally lower (on average 4.1 °Brix) than that for the urea (5.0 °Brix) and unfertilized treatments (4.8 °Brix). Concerning N-leaching, preliminary lysimeter data showed that cumulative N leaching over the crop cycle did not differ significantly among treatments. Future research will focus on replicating this experiment in spring 2025 to further investigate the effects of N-EEFs on processing tomato growth, yield, and nitrogen leaching.
