We evaluated the effect of criterions based on soil nitrate level, the expected fruit yield and previous experiments results to recommend nitrogen fertilizer rate to be applied in the tomato plants in unheated greenhouse. Two experiments were carried out, one in soil previously leached with water (Experiment 1) and the other without leaching (Experiment 2), aiming to simulate high and low soil nitrate level conditions. Six treatments were evaluated in a randomized complete-block design with four replicates. The treatments were based on the criterions: 1) fruit expected yield and soil and fertilizer contributions (PESF); 2) expected N amount in fruit and soil contribution (QECS); 3) expected N amount in fruit (QENF); 4) 280 kg ha-1 of N, the experimental recommended rate drip applied every 14 days (DRCO); 5) same as the prior treatment, but all N furrow applied at the transplant time (DRTR); 6) without nitrogen fertilizer application (TEST). The N rates varied from 0 to 570.8 kg ha-1. In both experiments the total and marketable fruits yield did not differ significantly among treatments which received N. Higher yields were obtained using the PESF criterion. In a general way, the N use, utilization and agronomic efficiency decreased as N applied amount increased in the two experiments. The PESF and DRTR criterions provided higher tomato yield and N fertilizer recovery efficiency.
Lycopersicon esculentum; nitrogen fertilizer manage; soil nitrate; expected yield of fruits; fertigation; nitrogen use efficiency
